كورس التدريب على الأنظمة النيوماتية من شركة هافنر
Pneumatic Training Course of HAFNER Pneumatik
Chapter 1 – Basic Concepts of Pneumatics
Chapter 2 – The general design of a pneumatic system and its components
Chapter 3 – Grouping and construction of control valves
Chapter 4 – Structure and function of directional valves
Chapter 5 – Schemes of directional control valves – ISO-symbols
Chapter 6 – Explanation of the Hafner type numbering system
Chapter 7 – The pneumatic cylinder – part 1
Chapter 8 – The pneumatic cylinder – part 2
Chapter 9 – The basics of air preparation
Chapter 10 – Air Preparation Units
Chapter 11 – Valves and Actuators with the NAMUR-Interface
Chapter 14 – Solutions for challenging environment – part 1
Chapter 15 – Solutions for challenging environment – part 2
Chapter 16 – Explosion protection
Chapter 1:
Basic Concepts of Pneumatics
Right of authorship: the content of the training (wording, drawings, pictures) are owned by the author. Any utilization except for
individual use is allowed only after permission of the author.
What is pneumatics?
Pneumatics is the utilization of compressed air in science and industry in order to perform mechanical
work and control. We can either talk about pneumatics or pneumatic systems.
In this course we define pneumatics as the control and transfer of power by using compressed air.
Advantages and Disadvantages of Compressed Air
Pneumatic systems have numerous advantages, the most important of which are:
 The medium, compressed air, can be easily extracted from our environment. There is no lack or
shortage of it.
 After usage the compressed air goes back to its original condition. It can be released into the
environment.
 Air can be compressed flexibly. Therefore it is ideal for absorbing shocks and vibrations.
 The distribution of compressed air can be easily handled with pipes and hoses.
 Compressed air can be used in fire- and explosion-hazardous environment.
 Both its pressure level and volume can be regulated quite easily. Therefore the energy brought to
the actuator can also be controlled quite easily and within broad parameters.
 The usage of pneumatic components is easy as well as their maintenance. Their functionality is
generally very reliable.
Besides these advantages there are some typical disadvantages:
 Compressed air – depending on its application – needs some preparation, especially filtration and
drying.
 Because of pricy electric energy and the limited efficiency of compressors, compressed air is a
relatively expensive means of energy.
 Because of air’s compressibility, the precise and load-independent positioning of the actuator(s)
is not possible.Chapter 1:
Basic Concepts of Pneumatics
Physical Fundamentals and Units of Measurement (metric system)
The SI-system of units is based on numerous basic and derived units of measurement. We do not cover
that in detail. [International System of Units, short SI (french): Système international d’unités]
Units of measurement that are relevant in pneumatics:
 Meter – m (length / distance)
 Kilogram – kg (weight / mass)
 Second – s (time)
 Kelvin – K (temperature)
Derived units that are used:
 Newton – N (force)
 Pascal – Pa (pressure)
Force
Force is any interaction that, when unopposed, will change the motion of an object. In other words, a force
can cause an object with mass to change its velocity (acceleration, change of shape). Force can also be
described as a push or pull. It is a vector quantity consisting of magnitude and direction.
 Symbol: F
 Unit: Newton
 Unit symbol: N
 In SI-based units:Chapter 1:
Basic Concepts of Pneumatics
Pressure
Pressure is the force applied perpendicular to the surface of an object per unit area over which the force is
distributed.
 Symbol: P
 Unit: Pascal
 Unit symbol: Pa
 In SI-based units:
For measuring pressure, the following multipliers are common:
1 kPa (Kilopascal) = 1,000 Pa
1 MPa (megapascal) = 1,000,000 Pa
In pneumatics we normally use the unit bar.
1 bar = 100,000 Pa = 0.1 MPa = 0.1 N/mm2
1 mbar = 0.001 bar
1 nbar = 0.000000001 bar
In some countries such as the USA or Great Britain the unit psi (pounds per square inch) is also still in use.
1 psi = 0.07 bar (rounded)
Standard atmospheric pressure is the pressure of the air on sea-level, which equals 1 atm
(atmosphere).
1 atm = 101,325 Pa = 1013.25 mbar (Millibar) or hPa (Hektopascal)
This unit is normally used in meteorology. Rounded and precise enough for most applications:
1 atm = 1 barChapter 1:
Basic Concepts of Pneumatics
Excess pressure or gauge pressure is the value of pressure above standard atmospheric pressure. It is
also called relative pressure.
In case absolute pressure is measured, standard atmospheric pressure is included. The scale starts at 0
Pa = total vacuum.
Absolute pressure = standard atmospheric pressure + gauge pressure (relative pressure)
Expressions:
 P(a) : Absolute pressure
 P(t) : Excess/Gauge pressure
 -P(t) : Vacuum
Examples:
 6 bar excess pressure = 6 bar(t)
 7 bar absolute pressure = 7 bar(a)
 0.7 bar absolute pressure = 0.7 bar(a) or -0.3 bar(t)
The expressions „excess pressure“ and „vacuum“ refer to a value larger or smaller than standard
atmospheric pressure.
There are different levels of vacuum:
Standard atmospheric pressure 101325 Pa = 1.01325 bar = 1 bar
Low vacuum (rough vacuum) 100 kPa … 3 kPa = 1 bar … 0.03 bar
Medium vacuum 3 kPa … 100 mPa = 0.03 bar … 0.001 mbar
High vacuum 100 mPa … 1 μPa = 0.001 mbar … 0.01 nbar
Ultra-high vacuum 100 nPa … 100 pPa
Extremely high vacuum < 100 pPa
Outer space 100 μPa … < 3 fPa
Perfect vacuum 0 Pa
In pneumatics we use the unit bar for vacuum as well as for excess pressure.
Unless there is any further indication, we normally work with excess pressure = relative pressure.Chapter 1:
Basic Concepts of Pneumatics
In practice:
We will calculate the force of a cylinder with a defined diameter at a specific pressure.
According to Pascal’s law:
 p: Pressure [Pascal]
 F: Force [N]
 A: Surface [m2]
How much force does a cylinder with a diameter of 40 mm apply at a pressure of 6 bar?
In order for us to use the correct units of measurement, we will use the unit Mpa for pressure. This
conforms to N/mm2. For the diameter we will use mm.
Diameter of the piston of the cylinder
d = 40 mm
The surface of the piston is to be calculated as a circular area:
In numbers:
At a (relative) working pressure p = 6 bar = 0.6
Thus:
In numbers:
This is the theoretical force. In practice we have to take losses due to friction into consideration
(approx. 5%).
Thus: A cylinder with a piston with the diameter of 40 mm at 6 bar pressure generates approx. 716 N
force. This translates into the ability to lift approx. 73 kg.Chapter 1:
Basic Concepts of Pneumatics
How much force does the same cylinder generate into the opposite direction
(pulling its rod back in)?
Due to the piston rod itself, the surface to push the rod out is larger than the surface to pull it
back in. The missing surface hast to be deducted.
D = diameter of piston (40 mm)
d = diameter of piston rod (16 mm)
After deducting 5% as loss for friction we find that the pulling force of the same cylinder is approx.
601 N, in comparison to the 716 N pushing force.
Chapter 2:
The General Design of a Pneumatic System
and its Components
Right of authorship: the content of the training (wording, drawings, pictures) are owned by the author. Any utilization except for
individual use is allowed only after permission of the author.
The route of compressed air from its generation to the consumer
In pneumatics compressed air is utilized for performing mechanical work and for control. In order
to do so we need different equipment to generate, treat and handle compressed air.
The graph displays the route of the environmental air from the compressor to the consumer of
compressed air:
When designing a pneumatic system, typically the individual elements are distributed spatially depending
on their task. Although they are spatially separated, they are still connected systematically.
Particles (solid)
Air filter
Compressor
Air dryer
Tank for compressed air
Including safety-valve and
condensate drain
Compressed air network
Air preparation
Filter, regulator, lubricator,
starter valve
Pneumatic tubes
and fittings
Valves
Control valves
Air
W Engine E
Thermal energy
Generation of
compressed air
Actuators W
Cylinders ConsumerChapter 2:
The General Design of a Pneumatic System
and its Components
Generation and transportation of compressed air
We will have a brief look at the following elements of pneumatic systems.
Air filter
The air filter is integrated into the intake of the compressor. It prevents large, polluting particles on the
outside from entering the air system. Through filtration, a major portion of unwanted particles can be kept
out of the system.
Compressor
The task of the compressor is to compress the air to the required pressure and in the required volume.
The engine consumes energy. The compressor transforms this energy and stores it as compressed air.
Unfortunately losses are severe. The screw compressor is the most common type. Piston compressors
are used as well.
Air Dryer and Pre-Filters
When air is compressed it loses its ability to hold water. Therefore water remains when air is compressed.
As this water, the condensate, would be disturbing the following processes, it needs to be removed from
the pneumatic system. In a so called refrigeration dryer the water condensates and can be removed.
There are also absorption dryers in which the water is absorbed by special materials.
The compressed air is also regularly polluted by oil from the compressor or particles that have not been
caught by its intake filter. Those can cause problems in the pneumatic system, e.g. in the valves. Often
times they are separated from the compressed air by using a central filter unit.
We will cover air preparation in a later chapter of the course in detail.
Tanks
Tanks are used for storing compressed air temporarily. The storage guarantees that the demand can be
covered securely. Often times you can find a condensate drain at the tank. The condensate can then drain
off through a valve. The drain is actuated manually or automatically.
Compressed Air Network
The task of the network is to distribute the compressed air from the compressor to the user(s). The size of
its tubes is important because it has a significant influence on the security of supply.
In general:
 The longer the tubes the bigger the loss of pressure due to friction.
 The more users are connected the bigger the orifice of the tubes needs to be.Chapter 2:
The General Design of a Pneumatic System
and its Components
The Quality of Compressed Air
The operational safety of an air system is directly linked to the quality of the compressed air.
In general:
‐ A „better“ = cleaner air increases the operational safety of the system as the risk of blockage and
wear is reduced.
‐ Please take into consideration that the manufacturers of the components and devices
communicate the quality requirements for the air in use. Air quality is standardized by
ISO 8573-1:2010.
Contaminants and purity classes – the standard ISO 8573-1
Particles, oil and water are the most important contaminants in compressed air. For each of these three
there are purity classes in the standard.
ISO 8573-1:2010
Class
Particles Water Oil
Maximum number of particles of
the following size [µm] / m³ of
compressed air
Concentration
Pressure dew
point
°C
Content of
liquid
[g/m3]
Total content
(liquid, aerosol,
gas)
[mg/m3]
0,1 … 0,5
µm
0,5 …1 µm 1 … 5 µm [mg/m3]

0. By definition of the user, less contamination than class 1
1. ≤ 20 000 ≤ 400 ≤ 10 – ≤ -70 – ≤ 0,01
2. ≤ 400 000 ≤ 6000 ≤ 100 – ≤ -40 – ≤ 0,1
3. – ≤ 90 000 ≤ 1000 – ≤ -20 – ≤ 1
4. – – ≤ 10 000 – ≤ +3 – ≤ 5
5. – – ≤ 100 000 – ≤ +7 – –
6. – – – ≤ 5 ≤ +10 – –
7. – – – 5 … 10 – ≤ 0,5 –
8. – – – – – 0,5 … 5 –
9. – – – – – 5 … 10 –
   X – – – > 10 – > 10 > 5
   Purity classes in accordance to standard ISO 8573-1
   For example: ISO 8573-1:2010 [4:3:3]
   Particles = class 4, water = class 3, oil = class 3Chapter 2:
   The General Design of a Pneumatic System
   and its Components
   High quality compressed air is (by definition) 100% oil free = class 0. Air of this quality is required in
   medical applications, the food-industry and electronic industry.
   Let’s not forget air pollution!
   When designing a compressed air system take environmental factors into consideration! Air pollution is
   concentrated when the air is compressed. Industries with high emissions in the neighbourhood can be of
   severe impact. Other factors such as a high concentration of ozone can influence your system and
   eventually harm seal materials as well. Never ignore climatic conditions. The dryer has to be more capable
   in a hot and humid environment.
   Therefore it is important that…
    we know what kind of air is sucked into our compressor
    we make sure that after compressing the air is dried, cleaned and potential oil is separated from it
    we consider the influence of the environmental factors (climate and pollution)
    components with very high loads are lubricated where necessary
   .. in order to guarantee a safe operation.
   The most important elements at the machine-level
   The sketch exemplifies a pneumatic system at the machine-level:
   The individual elements are represented by ISO-symbols, which are connected with lines. They display
   the route of the compressed air. In order to get a better overview we position the air preparation on the
   bottom and the actuators on the top of the drawing.
   Cylinder
   Flow regulators
   Control valve
   Air preparation units, short-form: FRLChapter 2:
   The General Design of a Pneumatic System
   and its Components
   We can form logic groups of the elements – as you can see in the drawing above:
    Air preparation
   o Filter
   o Pressure regulator
   o Lubricator
   o Switch-on valve
   o Soft start
   o …
   Control valves
   o Directional control valves
   o Other types of control valves
   o Logic elements
   o …
   Flow control valves, check-valves
   o Flow control valves, uni- or bidirectional
   o Exhaust flow-regulators
   o Non-return valves = check valves
   o Function fittings
   o …
    Actuators, cylinders
   o Cylinders
   o Rodless cylinders
   o Rotary actuators
   o …
    Tubes and fittings
   o To distribute compressed air and to connect different componentsChapter 2:
   The General Design of a Pneumatic System
   and its Components
   Hafner-Pneumatik distributes its products under the following groups and categories:
    HAFNER Valves
    Cylinders
    Process Valves
    Air Preparation Units
    Fittings
    Tubes
   We will study the function of all these groups in later chapters.Chapter 3:
   Grouping and construction of control valves
   Right of authorship: the content of the training (wording, drawings, pictures) are owned by the author. Any utilization except for
   individual use is allowed only after permission of the author.
   Pneumatic valves control pneumatic actuators such as cylinders, rotary actuators
   etc. The valves control the direction, speed (by flow) and force (by pressure) of the
   actuator.
   We can form the following groups of valves by distinguishing between their functions:
   The ISO-symbol tells you a valve’s function. By “reading” the symbol correctly you get hints of how to use
   it.
    Control of the effective direction of actuators – Directional control valves
   These valves control the actuators directly or they control other control valves.
   Application example: Control of a double acting cylinder by a 5/2-way hand-lever valve:
    Control of the amount of compressed air into / out of the actuator – Flow regulators
   These valves limit the amount of air flowing through them.
   Application example: We can add two uni-directional flow regulators to the example above.
   They control the speed of the cylinder by limiting the amount of air that is exhausted from it.
   Limiting the exhaust air is generally the better way in comparison to limiting the air-supply, since it
   results in a smoother movement of the piston.Chapter 3:
   Grouping and construction of control valves
    Pressure regulation – Pressure regulators
   These products keep the secondary pressure at a distinct level when the incoming pressure is
   volatile. As you know from Chapter 1, pressure determines the force of an actuator.
   Please note: The secondary pressure can only go as high as the entry pressure.
   Application example: We can add a pressure regulator to the example above. That way we can
   control the maximum force of the cylinder by regulating the maximum pressure of the system
   behind the pressure regulator. A pressure gauge indicates the secondary pressure.
    Quick exhaust – Quick exhaust valves
   These valves are designed to exhaust the air from an actuator quickly, which increases the speed
   of the piston.
   Application example: We can replace one of the flow-regulators with a quick exhaust valve in the
   example above. By doing so, the air in the chamber of the cylinder exhausts directly into the
   environment and the air does not flow back through the control valve. This maximizes the pushspeed of the piston.Chapter 3:
   Grouping and construction of control valves
    Logic elements
   These valves are not used for directly controlling actuators but to set up pneumatic control
   systems. Typical elements are: AND, OR, YES, NO. With these functions taken from the Boolean
   algebra, most (mathematical) problems can be solved.
   Application example: A single acting cylinder has to be controlled by either one OR the other of
   two 3/2-way valves. In case you want to make sure that the cylinder only moves if BOTH 3/2-way
   valves are actuated, replace the OR-gate by an AND-gate.
    Non-return valves = Check valves
   Check valves provide a free flow into only one direction. If compressed air comes from the
   opposite side, it is blocked.
   Application example: In order to save compressed air on a double acting cylinder that is „doing
   work“ in only one direction, the air-pressure that is needed to return the piston can be reduced
   significantly. A second pressure regulator is required for that. This regulator has to have a by-pass
   when the air exhausts from the relevant cylinder-side. The “one-way” by-pass is realized by using
   a check-valve.
   A typical application of a check-valve is the combination with a flow-regulator (see above
   example). This product is called Uni-directional flow regulator. In one direction the air can by-pass
   the regulator, whereas in the other direction the free flow is blocked and the air is forced to go
   through the regulator.Chapter 3:
   Grouping and construction of control valves
   General information on directional control valves
   Directional control valves are the most important elements of a pneumatic control system.
   In any fluid application they are utilized to define the route of the medium. They are used to control
   cylinders or other actuators. They can also control the movement and the direction of pneumatic motors
   or control other control valves.
   Directional control valves are not designed for regulating pressure or flow.
   We can form categories of directional control valves as follows:
    By basic design
   o Spool valves
   o Poppet valves
    By actuation
   o Mechanically actuated
   o Manually actuated
   o Pneumatically actuated
   o Electrically actuated (solenoid valves)
    By the number of (stable) positions
   o One stable position: single solenoid / single pilot valve or spring return valve.
   o Two stable positions: double solenoid / pilot valve, lever valve indexed.
   o 3-positions valves.
    Flow in basic position
   o For 2/2-way and 3/2-way valves with spring return
    Normally open
    Normally closed
   o For 3/3-, 4/3- and 5/3-way valves
    Centre closed
    Centre exhausted
    Centre pressurizedChapter 3:
   Grouping and construction of control valves
    By the number of ports / positions
   o 2/2-way (2 ports, 2 positions)
   o 3/2-way (3 ports, 2 positions)
   o 3/3-way (3 ports, 3 positions)
   o 4/2-way (4 ports, 2 positions – only one exhaust port)
   o 5/2-way (5 ports, 2 positions)
   o 4/3-way (4 ports, 3 positions – only one exhaust port)
   o 5/3-way (5 ports, 3 positions)
   The most common types are in bold. Besides the ones mentioned above there are more possibilities for
   special applications (e.g. 5/4-way valves, 7/3-way valves, …)Chapter 3:
   Grouping and construction of control valves
   Basic design of directional control valves
   Let’s have a look at the basic difference between spool and poppet valves.
   One of the basic elements of any directional control valve is the valve body. The body holds the parts of
   the valve together. The second important element is the moving part(s), which blocks and opens ports, or
   connects two or more of them with each other.
   The closing element can either be a spool or a valve disk. Therefore we distinguish between:
    Spool valves and
    Poppet valves.
   Spool valves
   In spool-valves the different ports are connected by axially moving a cylindrical spool.
   The drawings below display the closed and open position of a spool valve.
   Poppet valves
   In a poppet valve a valve-disc is pushed onto the valve-seat. When the disc is released again, the valve
   opens.
   The drawings below display the closed and open position of a poppet valve.Chapter 3:
   Grouping and construction of control valves
   Grouping directional control valves by modes of actuation
   Actuation means the source of energy which moves the closing element (disc or spool):
    mechanically a part of a machine pushes onto a stem or a roller-lever of the
   valve
    manually a human being operates a knob or a lever
    pneumatically a pressure signal moves the spool or the disc
    electrically / solenoid the plunger of a solenoid opens a poppet valve (lifts the disc
   on the seat)
    solenoid pilot the plunger of a solenoid opens a poppet valve, the moves a spool
   or a second (larger) disc.
   Solenoid valves can be distinguished as:
    Direct acting valves
   The (poppet) valve is directly opened by electric energy.
    Piloted valves (solenoid pilot spool valves)
   The main valve is generally a spool valve. The spool is driven by compressed air. This pilot air is
   controlled by a poppet valve. Part of the energy used to control the valve is supplied by the
   medium.
   The method of using the energy of the medium is not only used in spool valves. Poppet valves or
   diaphragm valves can be designed like that, too.
    Solenoid valves with external pilot feed
   This function is very similar to the solenoid pilot valves. The difference is that it’s not the energy of
   the medium of the main valve which is used to move the spool, but instead there is an additional
   port for compressed air. The solenoid system is separately supplied through that.Chapter 3:
   Grouping and construction of control valves
   Valves are available with different numbers of (stable) positions:
    One stable position
   As soon as the actuation is gone (i.e. the pneumatic signal or electric energy is cut, the button is
   released) the spool or the disc is forced back into its basic position. This movement can be
   powered either by a mechanical spring or by the energy of the medium (“air spring”).
    Two stable positions
   Whenever the actuation stops, the spool or disc stays in its current position until there is an
   actuation into the opposite direction.
    3 positions valves
   The spool / disc can generate 3 different kinds of connections of the ports (very rarely more).
   Manually actuated valves can be designed with 3 stable positions or in a way that the spool is
   driven into centre position by mechanical springs. Valves that are actuated in other ways are
   normally only available with a basic position.
   Description number of ports and number of positions:
   The following will only offer a first glance at this topic. You will receive more information in a later chapter.
   The valve is called X/Y-way valve, where X represents the number of ports in the main valve and Y the
   number of positons.
   Example:
   3/2-way valve
   The valve has 3 ports and
   2 positions.
   Number of positions
   Ports
   In Europe you will find mostly 2/2-, 3/2-, 5/2- and 5/3-way valves. In the USA 4/2 and 4/3-way valves
   are common.Chapter 3:
   Grouping and construction of control valves
   Application examples, distinguishing between solenoid valves:
   Direct acting solenoid valve (e.g.: MH 311 015)
   Basic design: poppet valve
   Control: solenoid – direct acting
   Number of ports / positions: 3/2-way
   Stable position(s): one, single solenoid
   Basic position: normally closed
   The electric energy consumed by the coil is directly used to open the
   valve disc.
   Solenoid-pilot valve (e.g.: MH 310 701)
   Although there are basically 2 valves inside this product – the
   main valve and the pilot valve -, the characteristics of the
   main valve define the product.
   Basic design: Main valve = spool valve
   Pilot valve = poppet valve
   Control: solenoid-pilot
   Number of ports / positions: 3/2-way
   Stable position(s): one, single solenoid
   Basic position: normally closed
   The electric energy consumed by the coil is used to operate the
   plunger in the pilot valve. The energy for the main valve is given by
   the medium.
   Solenoid valve with external pilot feed (e.g.: MEH 311 701)
   There are 2 valves inside this product as well.
   Once again the characteristics of the main valve define the product:
   Basic design: Main valve = spool valve
   Pilot valve = poppet valve
   Control: solenoid-pilot
   Number of ports / positions: 3/2-way
   Stable position(s): one, single solenoid
   Basic position: normally closed
   The electric energy consumed by the coil is used to operate the
   plunger in the pilot valve. The energy for the main valve is fed into the
   valve through an additional port in its head. Therefore the operation
   of the spool is independent from the medium’s pressure applied to
   the main valve.
   In the next chapter we will have a more detailed look at the function of directional control valves.
   External pilot feed portChapter 4:
   Structure and function of directional valves
   Right of authorship: the content of the training (wording, drawings, pictures) are owned by the author. Any utilization except for
   individual use is allowed only after permission of the author.
   Structure and function of directional valves
10. Structure of direct acting solenoid valves
    Direct acting solenoid valves are typically poppet valves. The movement of the valve disk opens and
    closes the route of the medium.
    The graphic below shows the cross section of an electrically actuated direct acting 3/2-way valve.
    Actuation: electrically (solenoid valve)
    The electric current generates a magnetic field which is used to lift
    the plunger in the operator tube. Without current the plunger is
    pushed down by a mechanic spring. In a 3-way valve the plunger
    has two seals = valve discs, one on the bottom and one on the top.
    They are marked in green.
    Control type: direct acting
    The force of the magnetic field is used to open the valve. There is
    no other source of energy, including the medium.
    Stable positions: one
    The valve has one stable position defined by the mechanic spring
    holding the plunger. When the electric signal is applied the valve
    switches. Once it is absent, the valve switches back.
    Basic position: normally closed
    Without electric energy the media is blocked at port 1, thus the
    valve is closed.
    Number of ports and positions: 3/2-way
    The valve has 3 ports and 2 positions.
    Typical features of direct acting valves:
     Orifice size: DN 1,2 … 3 mm
     Operating pressure: PN up to 10 bar
     Nominal flow: QN 10 … 210 l/min
     Port sizes: M5, G1/8“ and G1/4“
     Power consumption: 3W / 5VA and more
    This type of valve offers a small orifice size at 10 bar. Therefore the flow is relatively low. If a larger orifice
    size is required, the power consumption increases at the same rate.Chapter 4:
    Structure and function of directional valves
    Function:
    Pressure supply is connected to port 1. The force of the spring pushes the valve disk onto the seat and
    closes port 1. This force has to be larger than the force of the medium. In basic position the valve is open
    from port 2 to 3. (This is the normal basic position of a 3/2 way normally closed valve.)
    As soon as sufficient electric current is applied to the coil the valve disc is lifted from the valve seat of
    port 1. Simultaneously a second valve disc closes the seat between ports 2 and 3. Therefore the medium
    is free to flow between 1 and 2. The route between 2 and 3 is blocked.
    As soon as the electric current is absent, the valve switches back into basic position (1 closed, open from
    2 to 3).
    Important! Direct acting solenoid valves only use the electric energy provided to lift the plunger against
    the force of the mechanic spring. Therefore this type is mainly used for valves with smaller orifice size. The
    force of the spring has to be larger than the force of the medium below the seat and the generated force
    of the coil larger than the one of the spring.
    How are direct acting valves with larger orifice sizes designed?
    The graph below shows the cross section of an electrically actuated direct acting 2/2-way valve.
    The technical characteristics of this valve with large orifice
    size are:
     Operating pressure (max): PN 2,5 bar
     Nominal flow: QN 1.670 l/min
     Port size: G3/8“ and G1/2“
     Power consumption: 16W / 20VA
     Orifice size: DN 10 mm
    The power consumption of this valve is 16W/20VA, which is
    relatively high. The heat emission will be significant so the coil
    needs to be large.
    In order to overcome the mechanics explained above:
    “The larger the orifice (DN) or the required pressure range, the
    stronger the spring needs to be in order to close the seat” the
    design here is different:
    Pressure is not applied below the plunger but at the top. Therefore
    the valve can work with a softer (weaker) spring supported by the
    force of the medium. The applied electric force needs to overcome
    these 2 forces (spring plus medium) in order to open the valve. As
    mentioned above the required amount of electric energy is
    significant.
    We learn from this example that if valves with a large orifice used at
    high pressure are required, we need to use a second source of
    energy. This energy is typically coming from the medium.Chapter 4:
    Structure and function of directional valves
11. Structure of pilot operated spool valves
    Pilot operated valves (spool valves) consist of 2 parts. The graphic below shows the cross section of a 5/2-
    way single solenoid valve.
    The pilot valve is a 3/2-way poppet valve. The main valve is a 5/2-way spool valve.
    The characteristics of the main valve are:
    Basic design: spool valve
    The axial movement of the spool opens and closes the route between distinct ports in the valve. This
    movement is provided by the energy of the compressed air.
    Actuation: electrically (solenoid valve)
    The pilot valve is electrically actuated. For its function see the explanation above.
    Control: piloted
    The pilot valve controls the pilot air which is taken from port 1 of the main valve and internally supplied to
    the pilot valve. Port 2 of the pilot valve is connected to the top of the spool, triggering its movement.
    Number of stable positions: one
    The valve has one stable position. As soon as the electric signal is absent, the pilot valve exhausts and the
    spool is pushed into basic position by either a mechanic spring or the force of the medium feed from port
    1 of the main valve to the back-end of the spool (called air spring). Sometimes a combination of both
    types of springs is used.
    Basic position: Typically a 5/2-way valve is open from 1 to 2 and from 4 to 5. There is no such thing as
    “normally closed” or “normally open” for 5-way valves.
    Number of ports and positions:
    5/2, the valve has 5 ports and 2 positions.Chapter 4:
    Structure and function of directional valves
    The typical features of Hafner spool valves are:
     Orifice: DN 3 … 18 mm
     Operating pressure: PN 10 bar
     Nominal flow: QN 200 … 6.000 l/min
     Port size: M5 … G3/4“
     Medium: Compressed air
     Power consumption: 3W / 5VA
    Spool valves can combine a high flow (large orifice size) at a significant maximum pressure (the standard
    is around 10 bar, can be larger on request) with a low power consumption.
    In order to function correctly, the valves require a minimum pressure. If there is less pressure applied to
    the valve, the spool might not move. In this case the friction is too high.
    Overview of advantages and disadvantages:
    Directly actuated
    valve
    Small orifice
    Directly actuated
    valve
    Big orifice
    Piloted valve
    Big orifice
    Orifice / Flow small high high
    Max. Operating
    pressure
    high low high
    Min. Operating pressure 0 0 > 0
    Power consumption small high smallChapter 4:
    Structure and function of directional valves
    We will now introduce you to the function of 5-way solenoid spool valves which are pilot
    operated and explain the advantages of the Hafner design.
    The graph below shows the cross section of a 5/2-way single solenoid pilot valve.
    Function of a Hafner 5/2-way single solenoid valve (type: MH 510 / MD 510 / MMD 510)
    Pressure is connected to port 1. Through an axial hole in the spool compressed air is fed towards one end
    of the spool into the end-cap (right side in the drawing), there the air spring is built up. The spool is pushed
    into basic position. (Generally the valve can also be equipped with a mechanic spring). Simultaneously the
    pilot valve is supplied with compressed air through the pilot air duct (indicated in blue).
    The different sections inside the body of the main valve are separated by seals pressing onto the spool
    (green).
    In basic position air is allowed to flow from 1 to 2. Besides that ports 4 and 5 (exhaust port) are connected.
    Port 3 is closed.
    The main valve is piloted by a direct acting 3/2-way normally closed poppet valve that is supplied with air
    from the main valve. As the coil sitting on the operator tube is supplied with sufficient electric current the
    plunger is lifted. This opens the valve seat in the pilot valve and pilot air is fed to the “left side” of the spool.
    As the surface of the spool on that side is larger (approximately double) than on the spring side (right) the
    spool is moving towards the end cap.
    Result: The main valve switches. Air connected to port 1 is now free to flow to port 4. Ports 2 and 3 are
    connected, 5 is closed.
    When the current is taken away from the coil, the plunger drops and closing the seat in the pilot valve. Pilot
    air exhausts through the operator tube. The air spring becomes stronger than the opposite side of the
    spool and switches the main valve back into basic position.Chapter 4:
    Structure and function of directional valves
    Special features of Hafner valves with the “swimming O-ring”.
    By using high quality materials and modern means of manufacturing we can offer a range of products at
    high quality and with high reliability.
    Materials in use – standard valves:
     Body: anodized aluminum
     Spool: Stainless steel
     Operator system: brass, stainless steel, FKM
     Inner parts: brass, POM, NBR
     Seals: NBR, FPM (FKM)
    HAFNER also offers valves made from other materials or for specific applications such as:
     Stainless steel valves
     Brass-free products
     Low temperature valves (to -50°C)
     Poppet valves made from polyamide
     Valves for explosion hazardous environments (ATEX- approved)
    Features of the sealing system with the „swimming O-ring“:
    There is no deformation of the seal during assemblage of the valve – they are allowed to move
    independently within the brass cage. Without air pressure there is no contact pressure and, therefore, no
    friction. This construction also has consequences for the seals of the valves in use. When switching a 5/2-
    way valve only three of the five seals are exposed to pressure and applying friction to the spool.
     Becasue of the low friction, there is very
    little wear on the seals.
     As friction is low when pressure is low and
    friction as well as sealing effect increases
    with pressure the valves switch safely at
    low as well as at high pressure.
     Our customers benefit from high durability
    and extended lifetime, high flow combined
    with compact design as well as high
    reliability.Chapter 4:
    Structure and function of directional valves
    Communication of flow rates
    The Hafner catalogue contains information about the flow-rates of the valves l/min (liter per minute).
    The nominal flow is measured according to standard as follows:
    Supply pressure p1=6 bar, back pressure 5 bar
    The flow of the air at Δp=1 bar is indicated after expanding the air from 5 to 0 bar in l/min.
    Therefore the amount of „expanded“ compressed air is 5 times the volume of the air that is actually
    flowing.
    Important notice!
    Some manufacturers communicate the „maximum flow“ at „maximum operating pressure“. This value
    might be significantly higher. In case you design your pneumatic system for significantly lower pressure
    than 6 bar you might want to use components with a bigger orifice.
    HAFNER Pneumatik offers a very wide range of direct acting poppet valves and pilot operated
    spool valves with port size M5 to G 3/4” and a nominal flow of up to 6.000 l/min!
    In a later chapter we will introduce you to diaphragm valves and other poppet valve designs. Those are
    mainly used in process industry. In these industries, the medium is often times not compressed air.Chapter 5:
    ISO Schemes of directional control valves
    Schemes of directional valves
    The description of directional valves is standardized by DIN ISO 121.
    IMPORTANT! The ISO symbols display only the function of the valves. They do not give any further information
    about the design, flow, orifice size, etc.
    Basics of the ISO symbols:
     Each position the valve can take is represented by a square.
     The number of squares tells you the number of positions the valve can take.
     The air pathways are represented by lines.
     The direction of the airflow is represented by an arrow.
     In case air flows in both directions there is a double arrow.
     Closed ports are displayed as a T.
     The ports carry numbers. The numbers are only shown in the square with the basic position of the valve.
     The type of actuation is also symbolized.
     The ISO-symbol contains information concerning the stability of the positions and the reset.
    Directional valves – number of ports and positions
    The directional valves are described by the numbers of ports in the main valve (excluding pilot ports) and the
    number of positions the valve can take, [number of ports] / [number of positons]
    for example:
    2 squares = 2 positons
    3 ports
    Number of positions
    Number of ports
    In this case we speak of a 3/2 way valve (spoken: three two way valve). Each position of the valve is displayed in
    a square. The basic position is symbolized by the numbers of the ports.Chapter 5:
    ISO Schemes of directional control valves
    On the right hand side you can see the basic position of a normally closed 3/2-
    way valve.
     Port 1 = pressure supply is closed (blue).
     Port 2 = working, in basic position connected to port 3 = exhaust (red).
     Basic position or normal position drawn in green.
    The second square displays the actuated position of the valve.
     Valve has been actuated (actuation elements not shown here).
     Port 1 is connected to working port 2 (blue).
     Exhaust port 3 is closed (black).
     Actuated positon drawn in green.
    Symbols of the most common valves
    2/2-way valve
    Normally closed
    Normally open
    3/2-way valve
    Normally closed
    Normally openChapter 5:
    ISO Schemes of directional control valves
    4/2-way valve
    5/2-way valve
    4/3-way valve Center closed
    5/3-way valve Center closed
    Symbols of actuation elements and resets
    Apart from the squares showing the valve’s function, the symbols for its actuation elements and elements to
    reset/return it are shown on the left, respectively right side of them.
    Mechanically actuated,
    Actuation by stem
    With spring reset
    Mechanically actuated,
    Actuation by roller lever
    With air spring reset
    Mechanically actuated,
    Actuation by roller lever with idle
    return
    With combined (mechanical)
    spring and air spring resetChapter 5:
    ISO Schemes of directional control valves
    Manually actuated,
    Actuation with a push-button
    Manually actuated,
    Actuation by a lever
    Manually actuated,
    Actuation by a lever, indexed, 2
    positions
    Actuated by foot / foot valve
    Pneumatically actuated
    Electrically actuated,
    Direct actuated valve
    Electrically actuated,
    Solenoid pilot valve
    Manual override
    Pneumatically actuated,
    Differential piston, dominating side
    Pneumatically actuated,
    Differential piston.Chapter 5:
    ISO Schemes of directional control valves
    Numbering of ports
    All the ports in the valve are counted through. The numbers indicate the function of the port. The numbers
    always appear on the square for the valve’s basic/normal position. In case we talk about a valve with 2 stable
    positions, the numbers are shown for the „implicit standard position“.
    Basic position = normal position is the position the valve is in without actuation.
    Pressure supply 1 P
    Working port(s) 2, 4, (6) A, B, C
    Exhaust(s) 3, 5, 7 R, S, T
    Pilot ports(s) 10, 12, 14 X, Y, Z
    Examples:
    The following lever- and pneumatically actuated valves allow airflow in both directions (double arrows).
     Actuation : manually (by a lever)
     2 positions, both stable, indexed
     Number of pneumatic ports: 5
     Thus: 5 ports, 2 positions = 5/2-way valve
    Manually actuated, 5/2-way valve, indexed
    Type e.g.: HVR 520 701Chapter 5:
    ISO Schemes of directional control valves
     Actuation : pneumatically (with air)
     2 positions, one stable (with spring reset)
     Number of pneumatic ports: 5
     plus pilot port 14
     Thus: 5 ports, 2 positions = 5/2-way
    valve
    Pneumatically actuated 5/2-way valve, single
    pilot, mechanical spring reset
    Type e.g.: P 511 701
     Actuation : electrically (solenoid-pilot)
    including manual override.
     3 positions, one stable (spring centered)
     Number of pneumatic ports: 5
     Thus: 5 ports, 3 positions = 5/3-way valve
    Solenoid-pilot 5/3-way valve, 2 springs center
    the spool. Center position closed.
    Type e.g.: MH 531 701Chapter 5:
    ISO Schemes of directional control valves
    General information on circuits
    Looking at the following circuits you can see potential ways for using different types of directional valves.
    2/2-way valves
    2/2-way valves are for opening and closing. They block the medium or let it pass. 2/2-way valves can be either
    normally closed or normally open.
    In the scheme below two 2/2-way solenoid valves (S1 and S2) are used to control a cylinder with spring return
    (single acting) C1. Without actuation both solenoid valves are closed. In order to move the piston rod to the outer
    position (right) S2 has to be actuated. Compressed air is flowing from the source through S2 into the cylinder. In
    order to move the piston rod to the opposite position S2 needs to be de-energized and S1 has to be actuated. In
    case none of the valves are actuated, the piston rod stays in last position.
    (The symbol at the bottom displays an FRL-unit (filter, regulator, lubricator). The functions of cylinders as well as
    of air-preparation units will be discussed in a later chapter.)Chapter 5:
    ISO Schemes of directional control valves
    3/2-way valves
    3/2-way valves are mostly used to control single acting actuators. They can be normally closed or normally
    open. In the scheme below you can see two applications.
12. An electrically actuated 3/2-way valve (S1) controls the single acting cylinder (C1).
    When the valve is actuated, air flows from 1 to 2; the piston rod of the cylinder is moving to outer position.
    When the valve is de-energized, it switches back to normal position and the mechanic spring in the cylinder
    drives the piston rod back.
13. The double acting cylinder (C2) is controlled by a 5/2-way valve (Y1). Valve Y1 is controlled by an electrically
    actuated, normally closed 3/2-way valve (S2).
    Valve S2 is actuated (air flows from port 1 to port 2). The air actuates valve Y1. It switches and air flows from
    port 1 to port 4; the piston rod of cylinder C2 moves to the outer position.
    As soon as valve S2 is de-energized, air exhausts from port 2 to 3. Valve Y1 switches back into normal
    position because of the built-in mechanic spring. Compressed air in valve Y1 flows from 1 to 2 and the
    cylinder’s exhaust from 4 to 5 as the piston rod moves back in.Chapter 5:
    ISO Schemes of directional control valves
    4/2-way and 5/2-way valves
    4/2-way and 5/2-way, as well as 4/3-way and 5/3-way valves are usually used to control double acting
    actuators.
    In the example below a manually actuated valve (S1 or S2) controls a double acting cylinder (C1 or C2).
    Additionally, in order to control the speed of the cylinder, flow control silencers are in use.
    The major difference between the 4-way and the 5-way valve is that the 4-way valve offers only one exhaust port.
    Therefore the speed of the piston rod moving in or out cannot be controlled independently as the two chambers
    of cylinder C1 are exhausted through the same exhaust port 3 of valve S1.
    As for the 5/2-way valve (S2), the two chambers on cylinder (C2) are exhausted through separate exhaust
    ports (5 and 3). This offers the possibility to regulate the speed of the piston rod independently.Chapter 6:
    Explanation of the Hafner type numbering
    system
    Review of previous chapters
    In the earlier chapters we introduced you to the most important characteristics of directional valves.
    We have summarized them below:
    Categorizing control valves by the following criteria (chapter 3):
     Basic design
    (spool valve, poppet valve)
     Actuation
    (mechanically, manually, pneumatically or electrically actuated valves)
     Number of positions
    (2-, 3-, 4-, 5-way)
     Number of ports (in combination with positions)
    (2/2-way, 3/2-way, 5/2-way, 5/3-way, …)
     Normal position
    (for 2/2-and 3/2-way valves: normally closed or open, for 5/3-way valves: center closed, exhausted,
    pressurized)
    By design (chapter 4) we have to distinguish between poppet and spool valves. It is important to understand
    the difference in order to select the right valve for any application.
     2/2- or 3/2-way electrically and directly actuated poppet valves: directly controlled by the plunger of
    the solenoid system.
     3- or 5-way electrically actuated spool valves: controlled by an additional pilot-valve
    Introduction to directional valves (chapter 5):
     ISO symbols and their meaning when it comes to function and positions
     Numbering of their portsChapter 6:
    Explanation of the Hafner type numbering
    system
    Explanation of the Hafner type numbering system
    The HAFNER type numbers are a combination of letters and numbers, which carry further meaning. The most
    important characteristics of the valves are to be found in the type number.
    The type number contains 3 major blocks (1-3)
    M H 5 1 0 7 0 1
    1 2 3 4
    … the fourth block indicates a special variation.
    M H 5 1 0 7 0 1 G
    1 2 3 4
    To explain the system we use the valve
    type MH 510 701 G. This number has 3
    main parts plus a suffix (block 4, variable).
    The valve is defined by the 3 main blocks.
    The fourth block is there to indicate extra
    features, special materials etc.
    Although there are some exceptions, this
    standard covers most of the products.
    Block 1 – actuation
    The first letter defines the mode of actuation of the valve
    Type
    M H 5 1 0 7 0 1
    1 2 3
     B = Mechanically or manually actuated
     H = Hand lever valve
     P = Pneumatically actuated
     M = Solenoid valveChapter 6:
    Explanation of the Hafner type numbering
    system
    Type
    The next letter(s) give further information
    M H 5 1 0 7 0 1
    1 2 3
    This list is not limited to the types mentioned
    above, but only gives an overview about the
    most common products. There are many
    more.
     B = Mechanically or manually actuated
    o BV = stem actuated valve
    o BR = roller lever valve
    o BL = roller lever valve with idle return
    o BA = stem valve with coupling for knob
    o BH = push-pull valve
     H = Hand lever valve
    o HV = with spring return (one stable position)
    o HVR = indexed
    o HV(R)N = valve-body with interface following
    NAMUR-standard
     P = Pneumatically actuated – no further information for
    standard products
    o PN = valve-body with NAMUR-interface
     M = Solenoid valve
    o MH = with manual override to turn, normally closed
    o MD = momentary manual override to push, normally
    closed
    o MOH = normally open MH valve (2/2 and 3/2-way)
    o MOD = normally open MD valve (2/2 and 3/2-way)
    o MEH / MED = with external pilot feed
    o MEOH = n.o. and with external pilot feed
    o MK = modified MH-valve, with solenoid MA16 (low
    power consumption 1.8W and for valve terminals)
    o MNH / MND = valve-body with NAMUR-interface
    o MNOH = valve-body with NAMUR-interface, normally
    openChapter 6:
    Explanation of the Hafner type numbering
    system
    Block 2
    The second block contains information about the number of ports, the number of stable positions and the type
    of spring.
    Number of ports in main valve
    M H 5 1 0 7 0 1
    1 2 3
    The first digit displays the number of ports.
     2 = 2-way = 2 ports (2/2)
     3 = 3-way = 3 ports (3/2 or 3/3)
     5 = 5-way = 5 ports (5/2 or 5/3)
    Positions
    M H 5 1 0 7 0 1
    1 2 3
    The second digit displays the number of positions
    and whether the valve has one or two stable
    positions.
     1 = one stable position (single sol. / pilot)
     2 = two stable positions (double sol. / pilot)
     3 = 3-postions ( _/3-way valves)
    Return
    M H 5 1 0 7 0 1
    1 2 3
    In combination with the second digit (in this case
    “1”), the third digit informs about the type of spring:
     10 = air spring (no mechanic spring)
     11 = mechanic spring inside, can also be
    executed as a combination of an air- with a
    mechanic spring. At double solenoid valves
    the third number is always a “0” as they don’t
    have any spring return.
    Center position
    for 3-position valves (e.g. MH 531 701)
    M H 5 3 1 7 0 1
    1 2 3
    In case we are talking about a 3-position valve, the
    third number defines the center position:
     31 = Center closed
     32 = Center exhausted
     33 = Center pressurizedChapter 6:
    Explanation of the Hafner type numbering
    system
    Block 3
    Block 3 contains information about orifice size and ports.
    Orifice size
    M H 5 1 0 7 0 1
    1 2 3
    The first digit(s) represent the orifice and thread size.
     20 = DN 2 mm, port: M5
     30 = DN 3 mm, port: M5 or G1/8″
     34 = DN 3 mm, 4 mm push-in fitting
     40 = DN 4 mm, port: G1/8″
     46 = DN 4 mm, 6 mm push-in fitting
     50 = DN 5 mm, port: G1/8″
     70 = DN 7 mm, port: G1/4″
     80 = DN 8 mm, port: G1/4″
     10 = DN 10 mm, port: G3/8″
     12 = DN 12 mm, port: G1/2″
     18 = DN 18 mm, port: G3/4″
    The orifice size also lets us know about the flow:
     20 = DN 2 mm, flow: 115 … 125 l/min
     30 = DN 3 mm, flow: 280 l/min
     40 = DN 4 mm, flow: 450 l/min
     50 = DN 5 mm, flow: 650 l/min
     70 = DN 7 mm, flow: 1250 l/min
     80 = DN 8 mm, flow 1450 l/min
     10 = DN 10 mm, flow: 2250 l/min
     12 = DN 12 mm, flow: 3000 l/min
     18 = DN 18 mm, flow: 6000 l/min
    You can get more information about flow from the
    catalogue.
    Ports are BSP threaded by default.
    NPT threads are to be indicated by a “NPT” suffix
    in block 4.
    The second digit in block 3 defines the type of
    connection:
     0 = tapped working ports 2 and 4
     4 = 4 mm push-in fitting(s) in port(s) 2
    and 4
     6 = 6 mm push-in fitting(s) in port(s) 2
    and 4Chapter 6:
    Explanation of the Hafner type numbering
    system
    Position of ports
    M H 5 1 0 7 0 1
    1 2 3
    The last digit in block 3 defines the position of the ports within
    the body:
     1 = Standard, ports on both sides of the valve
     2 = All the ports on one side
     3 = For manifold-plates only, supply and exhaust on
    one side, working ports on opposite side in the valve
     4 = For manifold-plates only, all the ports are in the
    plate.
    Standard (e.g. MH 510 701, MH 510 703)
    All the ports on one side (e.g. MH 510 502, MH 510 704)Chapter 6:
    Explanation of the Hafner type numbering
    system
    On the following four pages we explain some exemplary type numbers based on
    catalogue items:
    BV 311 201 Block 1
    Actuation: BV
     B = Mechanically actuated
     V = Stem
    Block 2
     First digit: number of ports = 3
     Second digit: number of (stable) positions = 1
     Third digit: return = 1 = mechanic spring
     3/2-way valve
     Mechanic spring return
    Block 3
    First and second digit: orifice size = 20 = orifice size 2 mm
    Third digit: position of the ports = 1 = standard
     M5 tapped ports (belongs to orifice size 2 mm)
     Port 1 and 3 on one side, working port 2 on the
    opposite side.
    Therefore the valve BV 311 201 is a:
     Stem actuated valve
     3/2-way with mechanic spring return
     M5-ports on both sides of the valve, orifice size 2 mmChapter 6:
    Explanation of the Hafner type numbering
    system
    HVR 520 701 Block 1
    Actuation: HVR
     H = Hand lever valve
     VR = Indexed (without spring return)
    Block 2
     First digit: number of ports = 5
     Second digit: number of (stable) positions = 2
     Third digit: return 0 = non = 2 stable positions
     5/2-way valve
     2 stable positions
    Block 3
    First and second digit: orifice size = 70 = orifice size 7 mm
    Third digit: position of the ports = 1 = standard
     G 1/4” tapped ports (belongs to orifice size 7 mm)
     Ports 1, 3, 5 on one side, working ports 2, 4 on the
    opposite side.
    Therefore the valve HVR 520 701 is a:
     Hand-lever valve
     5/2-way indexed
     G 1/4” ports on both sides of the valve, orifice size 7 mmChapter 6:
    Explanation of the Hafner type numbering
    system
    MD 531 401 24 DC Block 1
    Actuation: MD
     M = Solenoid valve
     D = Manual override to push, momentary
    Block 2
     First digit: number of ports = 5
     Second digit: number of positions = 3
     Third digit (if second one is a 3): center 1 = closed
     5/3-way valve
     Center closed
    Block 3
    First and second digit: orifice size = 40 = orifice size 4 mm
    Third digit: position of the ports = 1 = standard
     G 1/8” tapped ports (belongs to orifice size 4 mm)
     Ports 1, 3, 5 on one side, working ports 2, 4 on the
    opposite side.
    Block 4
    (Misc.) 24DC for MD and MK valves only: voltage
    Therefore the valve MD 531 401 24 DC is a:
     Solenoid valve with manual override to push
     5/3-way center closed
     G 1/8” ports on both sides of the valve, orifice size 4 mm
     Integrated solenoid 24V DCChapter 6:
    Explanation of the Hafner type numbering
    system
    MNH 311 701 Block 1
    Actuation: MNH
     M = Solenoid valve
     N = NAMUR-interface
     H = Manual override to turn
    Block 2
     First digit: number of ports = 3
     Second digit: number of (stable) positions = 1
     Third digit: return = 1 = mechanic spring inside
    (in this case a combined spring).
     3/2-way valve
     Normally closed
     With combined mech.-pneum. spring
    Block 3
    First and second digit: orifice size = 70 = orifice size 7
    Third digit: position of the ports = 1 = standard, in combination with
    the N in Block 1 with NAMUR-interface.
     G 1/4” tapped ports (belongs to orifice size 7 mm)
     Ports 1, 3, 5 on one side, working ports in
    accordance to NAMUR-standard (VDI/VDE 3845)
    Therefore the valve MNH 311 701 is a:
     Solenoid valve with manual override to turn
     3/2-way n.c.
     NAMUR-interface and ports 1, 3, 5 G 1/4, orifice size 7 mmChapter 6:
    Explanation of the Hafner type numbering
    system
    As you can see the HAFNER type numbering system is following a standard that allows you to understand what
    type of valve is in use or required whenever those numbers are mentioned.
    An overview about the structure of the Hafner type numbers can also be found on page 16 and 17 in the
    valve catalogue 2016:Chapter 7:
    The pneumatic cylinder – part 1
    Right of authorship: the content of the training (wording, drawings, pictures) are owned by the author. Any utilization except for
    individual use is allowed only after permission of the author.
    In the earlier chapters we looked at the basic design of a pneumatic system and its most important elements:
     Air preparation
     Control valves
     Flow-regulators
     Actuators / cylinders
     Tubes and fittings
    In this chapter we will be looking at pneumatic cylinders. Cylinders are the most important means of
    actuation in pneumatics. The cylinder transfers the energy that is stored in the compressed air into
    movement.
    They can be classified by:
     Design
    o Cylinders with piston rods
    o Rodless cylinders
    o Diaphragm cylinders
    o Rotary cylinders
     Movement
    o Linear
    o Rotary = turning
     Function
    o Single-acting
    o Double-acting
    o 3- or 4-positions
     Cushioning
    o Adjustable, pneumatic cushioning
    o Flexible cushioning
    o Without cushioning
    There is a very wide variety of pneumatic cylinders. In this training we will only focus the most common ones.Chapter 7:
    The pneumatic cylinder – part 1
    Cylinders with piston rods
    Cylinders are available in different types and follow different international standards. Besides the ones that follow
    standards there are also “non-standardized cylinders”. Especially before the standardization into
    DIN/ ISO norms 6431 and 6432, there were numerous cylinder-types offered by different manufacturers.
    Common standard cylinders are:
     Mini cartridge cylinders
     Round cylinders | DIN ISO 6432
     Profile cylinders | ISO 15552 | VDMA 24562 | (old norm: DIN ISO 6431)
     Compact cylinders | ISO 21287 | UNITOP
     Short stroke cylinders
     Tie rod cylinders | ISO 15552Chapter 7:
    The pneumatic cylinder – part 1
    We will look at the following characteristics:
14. Design
15. Diameter and stroke
16. Movement
17. Number of positions
18. ISO symbols
19. Cushioning  chapter 8
20. Detection of cylinder position (magnetic)  chapter 8
21. Speed control  chapter 8
22. Design of a cylinder
    Most of the cylinders with a piston rod contain the following parts: a tube that is closed on both ends with a
    cap and head. Inside the tube seen below a piston rod moves with a drive piston.
    The movement of the piston is triggered by compressed air, controlled by a directional valve. The direction is
    defined by the chamber into which compressed air is allowed to flow inside the cylinder.
    The force is transferred by the piston rod.
    Components of a piston rod cylinder:Chapter 7:
    The pneumatic cylinder – part 1
23. Diameter and stroke
    Diameter and stroke are the most important attributes of a cylinder.
    e.g. HAFNER Cylinder DIP: DIP 40/320
    Type numbering system:
     DIP – type of cylinder / design
    (DIP = ISO 15552 standard – double-acting cylinder – adjustable cushioning – magnetic piston)
     40 – diameter of the piston [mm]
     320 – stroke of the cylinder [mm]
    The diameter is actually the diameter of the piston. The diameter of the cylinder defines its force relative to the
    air-pressure.
    The stroke tells us how many millimetres the piston and therefore the piston rod can travel.Chapter 7:
    The pneumatic cylinder – part 1
    If the stroke is long, the forces on the bearing between head and piston rod are high. In order to avoid a defect
    we recommend to select a larger diameter (cylinders with larger piston diameters also offer larger piston rod
    diameters).
    In case of very long strokes or radial forces we recommend the use of a guide unit.
    Pictures: DIP cylinder with assembled guide unit
    Diameters and strokes are standardized, the most common values are:
    Piston diameters [mm]:
    | ø8 | ø10 | ø12 | ø16 | ø20 | ø25 | ø32 | ø40 | ø50 | ø63 | ø80 | ø100 | ø125 | ø160 | ø200 | ø250 | ø320 |
    Stroke lengths [mm]:
    | 5 | 10 | 15 | 20 | 25 | 30 | 40 | 50 | 60 | 80 | 100 | 125 | 160 | 200 | 250 | 320 | 400 | 500 | …
    The available diameters depend on, and are limited by, the type / standard. The availability of strokes on the
    other hand is less limited.
    The maximum force generated by a cylinder depends on:
     Operating pressure
     Diameter of the piston
     Friction of the inner parts
    As an example we calculate the force of a cylinder DIL 40/320 at 6 bar.Chapter 7:
    The pneumatic cylinder – part 1
    Piston diameter:
    Surface of drive piston:
    Operating pressure:
    Calculation of the force:
    Thus we have a theoretical force of 753,6 N.
    As a rule of thumb we can deduct 5% for friction. Therefore a cylinder with a piston diameter of 40 mm, and an
    operating pressure of 6 bar, can exert a force of approx. 716 N.
    If we divide the force by gravity (9,81 m/s2), we find – in practice – that our cylinder can hold a mass of
    about 73 kg.
    CAUTION! We can only hold the weight with this force, we cannot move it yet!
    If we want to move a weight we have to (again) take gravity into consideration. Only then our cylinder is not only
    able to hold a weight but to perform work.Chapter 7:
    The pneumatic cylinder – part 1
24. The Movement of a cylinder
    We call the two end-positions of a cylinder positive / plus and negative / minus positions.
    Therefore we also call the two chambers inside the cylinder the plus and the minus chamber.
    Positive movement Negative movement
    The position where the piston rod is out of the cylinder the furthest possible is called the plus end-position. In
    order to reach it, the plus chamber needs to be inflated.
    The minus end-position is positioned on the opposite side; the minus chamber needs to be inflated.
    The cylinder cannot reach an end-position if the opposite chamber is not fully exhausted!
25. Stable positions of a cylinder
    We distinguish between single-acting and double-acting cylinders.
    In single-acting cylinders only one chamber is inflated with compressed air. Therefore work is performed only
    in one direction by compressed air. For the movement into the opposite direction a mechanic spring is the
    source of energy. The stroke is limited by the length of the spring. In general single-acting cylinders offer a
    relatively short stroke.
    Two different types of single-acting cylinders are available:
    Single-acting cylinder with base position minus Single-acting cylinder with base position plus
    (spring between head and piston) (spring between cap and piston)Chapter 7:
    The pneumatic cylinder – part 1
    Double-acting cylinders are driven in both directions by compressed air. They are always used when work has to
    be performed in both directions or when the required stroke is longer than the available springs.
    There are different designs for different applications:
     Double-acting cylinder
    (standard design)
     Double-acting cylinder with through piston rod
    (Cylinder has a piston rod on both ends)Chapter 7:
    The pneumatic cylinder – part 1
     Double-acting cylinder, guided / non-rotating rod
    (integrated guide unit for higher radial forces)
     Cylinders with non-rotating piston rods
    (If the application does not allow a rotation of the piston rod, either a rod that does not have circular
    cross section or a double piston-rod is in use)
     Multi-position cylinders
    (Two cylinders are assembled back to back. Thus 4 different strokes with different lengths are possible.)
     Tandem cylinder
    (Target: Higher force of the cylinder without increasing its diameter. In order to achieve this, two or more
    cylinders are connected to each other so that their piston rods are connected as well and working in
    line. In other words several pistons use the same piston rod. Thus the force adds up.)Chapter 7:
    The pneumatic cylinder – part 1
26. ISO symbols
    In order to distinguish between cylinders, there are also well defined ISO symbols and schemes indicating their
    different functions. These do not however indicate their size, diameter, stroke, ISO-standard etc.
    Double-acting cylinder
    („standard design“)
    Double-acting cylinder with
    magnetic piston
    The piston is different from figure 1,
    indicating the magnetic piston.
    Double-acting cylinder with
    adjustable cushioning
    Cushioning symbolized by two
    rectangular objects; arrow for
    „adjustable“.
    Double-acting cylinder with
    adjustable cushioning and
    magnetic piston
    Combination of figure 2 and 3.
    Double-acting cylinder with through
    piston rod, adjustable cushioning
    and magnetic piston
    The through piston rod is added.
    Single-acting cylinder (MINUS) Single-acting cylinder with spring in
    minus chamber
    Single-acting cylinder (PLUS) Single-acting cylinder with spring in
    Plus chamberChapter 7:
    The pneumatic cylinder – part 1
    We introduced the following expressions:
     Cushioning
     Magnetic piston
    Their explanation will follow in the next chapter. Just to give you a short insight:
     The adjustable cushioning slows the cylinder down when the piston is entering either head or cap. The
    idea is to avoid a hard shock when the piston hits these elements.
     The magnetic piston is required if we want to check the positon of the piston with a REED-switch.
    The switch is added onto the outside of the cylinder. When the piston travels by, the switch sends a
    signal.Chapter 8:
    The pneumatic cylinder – part 2
    Right of authorship: the content of the training (wording, drawings, pictures) are owned by the author. Any utilization except for
    individual use is allowed only after permission of the author.
    In chapter 7 we looked at the most important features and characteristics of a pneumatic cylinder:
27. Design
28. Diameter and stroke
29. Movement
30. Number of positions
31. ISO symbols
    In this chapter we will cover:
32. Cushioning
33. Detection of cylinder position (magnetic)
34. Speed control
35. International Standards
36. Cushioning
    Compressed air can enter the cylinder at a very high speed. If the piston hits the cap or head at high speed, it
    can lead to damage. In order to avoid that, most cylinders are equipped with end-of-stroke absorbers /
    cushioning’s, which reduce the piston’s speed shortly before it reaches the cap and thus reduce shock.
    There are two ways to reduce the shock:
    • flexible shock absorbers
    • adjustable cushioningChapter 8:
    The pneumatic cylinder – part 2
    Flexible Shock Absorbers
    The easiest way to avoid a hard shock is to assemble some kind of soft material between the piston and the
    cap/head. It comes in form of a ring which is usually made from polyurethane and thus offers very good shockabsorption. This design is often times used for cylinders with rather small diameters where the strain is not that
    high. The same kind is used for compact cylinders where the small dimensions do not allow any larger devices.
    The flexible shock absorbers are highlighted with red arrows in the graph below.
    Adjustable (pneumatic) Cushioning
    The adjustable pneumatic cushioning is used if it comes to stronger forces due to higher speeds or bigger sizes.
    This way of reducing shock is efficient as well as wear-free. During the last 10 to 50 mm of its travel (depending
    on the size of the cylinder), the piston builds an air cushion inside the cylinder. The degree of cushioning
    (= speed reduction) can be adjusted at both ends of the cylinder for both sides respectively. The mechanism is a
    flow-regulating valve.
    Both tie-rod and profile cylinders offer that feature, according to ISO 15552. Rodless cylinders often offer it, too.
    Round cylinders (ISO 6432) of larger diameters, as well as special cylinders, can be equipped accordingly.
    The components of the cushioning are marked with red in the graph below.Chapter 8:
    The pneumatic cylinder – part 2
    Below you can learn more about the function of the adjustable pneumatic cushioning:
37. cylinder head
38. throttle screw
39. cylinder tube
40. brake piston
41. cylinder piston
42. piston rod
43. braking chamber
44. port / air connection
    graph 1. graph 2.
    During the movement of the piston, the compressed air exhausts through the port (8) (graph 1).
    Before the piston reaches the head, the brake piston (4) – which is part of the cylinder piston (5) – prevents
    the air within the braking chamber (7) from exhausting through the port (8) (graph 2). The air trapped there can
    only exhaust through a much smaller orifice. The orifice can be adjusted with the throttle screw.
    Inside the braking chamber (7) pressure goes up and generates a temporary air spring. Its resistance remains
    there until the air has completely exhausted through the throttle screw (2).
    CAUTION! The throttle screw can only adjust the degree of cushioning / speed of the cylinder piston for the last
    10 to 50 mm of its movement.
    How to adjust the speed of a cylinder in general will be covered later in this chapter.Chapter 8:
    The pneumatic cylinder – part 2
45. Detection of cylinder position (magnetic)
    Sensors are absolutely necessary elements when it comes to industrial automation. Sensors generate
    information and control entire processes.
    In order to detect the position of the piston, sensors which are triggered by a magnetic field are assembled onto
    the pneumatic cylinder. The cylinder piston is equipped with a magnet so that the sensor can receive a
    signal.
    The sensor is assembled onto the cylinder in the
    position where the signal is required.
    Many cylinders have an outer profile
    that offers space for assembling the
    sensor directly.
    Sensor / switch … … assembled onto the tube
    There are two different types of sensors / switches:
    • REED switch
    • Inductive, PNP switchChapter 8:
    The pneumatic cylinder – part 2
    REED switch
    REED switches consist of two ferromagnetic nickel-iron wires. They are packed together in a glass tube filled
    with a noble gas and are made from a magnetic material.
    The magnet in the piston induces a magnetic
    field, making the shifting wires approach each
    other.
    The shifting wires connect and close the
    electric circuit.
    The switches have an LED that starts to glow
    when the circuit is closed.
    The REED switches have 2 wires, which can
    be operated between 3 and 230 Volt AC/DC.
    SymbolChapter 8:
    The pneumatic cylinder – part 2
    Inductive, PNP switch
    The function of the inductive PNP switch is based on the principles of a bipolar junction transistor. When the
    magnet that is built into the piston gets close to the switch, it gives a well-defined signal. The switch can be used
    ‘normally open’ as well as ‘normally closed’.
    An LED displays the condition of the switch.
    PNP switches have generally 3 wires. They work within a voltage range of 5 to 30 V DC.
    Symbol
    Advantages of the PNP switch in comparison to the REED switch:
    • No movable parts inside
    • Higher frequency
    • Higher durabilityChapter 8:
    The pneumatic cylinder – part 2
46. Speed control of cylinders
    To control the speed of a pneumatic cylinder (actuator) over the entire stroke, flow regulators or flow-regulating
    silencers can be used.
    For the positive movement of a double-acting
    cylinder, compressed air enters the plus chamber.
    Simultaneously, the air in the minus chamber exits.
    (controlled by a 5/2-way valve)
    Ideally, we control the speed of the cylinder by
    reducing the flow of the exiting air.
    To control the speed, we regulate the exhaust air flowing out of the cylinder chamber. We thereby avoid an
    immediate exhaust. The air is in both chambers available as long as the piston has reached the end position. The
    movement is therefore very smooth.
    CAUTION! In order to set the speed of the cylinder and to get a smooth movement, it is always the exhaust air
    that has to be controlled.
    To do this there are different products available for speed regulation:
    • Uni-directional flow regulator – block form flow regulator
    • Uni-directional flow regulator – function fitting to be assembled in the cylinder
    • Uni-directional flow regulator – function fitting to be assembled in the valve
    • Exhaust flow regulator – to be assembled into the valveChapter 8:
    The pneumatic cylinder – part 2
    Uni-directional flow regulator = one-way flow control valve
    In order to allow compressed air to flow into the cylinder at full speed, while allowing it to exhaust slowly, we use a
    one-way flow control valve.
    Throttled air-flow:
    Air flowing this way has to pass the throttle (flow
    regulator) as the other path is blocked by a check
    valve.
    Free air-flow:
    Air flowing the opposite direction can bypass the
    throttle and passes through the check-valve (nonreturn valve).
    By using two one-way flow control valves, we can independently regulate the positive as well as the negative
    movement of the cylinder.
    During positive movement, air bypasses the flow
    regulator into the plus chamber. Air that is supposed
    to leave the minus chamber has to pass through the
    throttle in the flow regulator. This limits the speed of
    the cylinder.
    During negative movement, the air flows through
    the same block form flow regulators. This time the air
    flowing into the minus chamber bypasses the throttle
    while the exhaust of the plus chamber is regulated.
    The speed of the positive movement has to be
    adjusted at the regulator of the minus chamber and
    vice versa.
    There are many different designs of flow-regulators available and their sizes differ depending on the
    manufacturer.Chapter 8:
    The pneumatic cylinder – part 2
    Function fittings are screwed either directly into the cylinder or into the valve. Therefore there are two
    different types, one for each area of application.
    • A flow regulator for a cylinder reduces the flow that streams from the thread to the push-in fitting (out
    of the cylinder).
    • A flow regulator for a valve regulates the flow from the push-in fitting to the threaded port (into the
    valve).
    There are products where the manual adjustment can be done with a screw-driver or with a knurled-head screw.
    Function fitting with one-way flow regulator for cylinder
    Function fitting with one-way flow regulator for valve
    One-way flow regulator with two push-in fittings
    Block form flow regulator with two female portsChapter 8:
    The pneumatic cylinder – part 2
    Sample circuits for cylinders with speed control
    Below you see three different ways of speed control for a double-acting cylinder, with air supply via a joint FRL.
    Circuit 1 (Cylinder C1):
    The double-acting cylinder C1 is controlled by the single solenoid 5/2-way valve S1. As soon as the valve is
    actuated, air flows into the Plus chamber of the cylinder via F1.1. The air flow is not restricted by F 1.1.
    Simultaneously, air needs to exhaust from the Minus chamber of the cylinder via F1.2. This flow is restricted by
    F1.2. Via the directional valve S1 (port 3), the air is finally exhausted. As soon as the electric actuation of the
    directional valve S1 is taken away, the valve switches back to normal position. Air flows at full speed via F1.2 into
    the Minus chamber of cylinder C1, while the air in the Plus chamber exits via F1.1 and S1, exhausting at port 5 of
    S1. This flow is restricted by / adjusted at F1.1. The positive movement of the cylinder is regulated at F1.2, the
    negative movement is restricted at F1.1. F1.1. and F1.2. can be screwed either into the cylinder or the valve, but
    the correct version has to be selected either way!
    Circuit 2 (Cylinder C2):
    The double-acting cylinder C2 is controlled by the single solenoid 5/2-way valve S2. The speed of the cylinder is
    adjusted at flow control silencers F2.1 and F2.2. , which are screwed into the valve. For positive movement, the
    directional valve S2 needs to be actuated. Air streams at full speed from port 1 to port 4 of the valve and into the
    Plus chamber of cylinder C2. At the same time air needs to exhaust from the Minus chamber of the cylinder. The
    air streams into port 2 of the valve S2. Its flow is restricted by F2.2 before leaving the valve S2 at port 3. For
    negative movement, the valve switches back into standard position. The Minus chamber is supplied via port 2 of
    valve S2. The exhaust from the Plus chamber is restricted by F2.1 in port 5 of the valve S2.
    Circuit 3 (Cylinder C3):
    The double-acting cylinder C3 is controlled by the single solenoid 5/2-way valve S3. For an extremely quick
    positive movement after actuating the valve, the Minus chamber is exhausted by the quick exhaust valve F3.2.;
    the exhaust air does not pass the directional control valve S3. For negative movement, the valve S3 needs to
    switch back into normal position. The exhaust air of the Plus chamber has to go through the one-way flow
    regulator F3.1Chapter 8:
    The pneumatic cylinder – part 2
47. International Standards
    The most common cylinders in pneumatics have been standardized, the target being maximum compatibility
    between products of different manufacturers.
    The most common cylinder standards are:
    • ISO 15552 | VDMA 24562 | DIN ISO 6431 (old standard) | for profile and tie-rod cylinders.Chapter 8:
    The pneumatic cylinder – part 2
    • DIN ISO 6432 | round cylindersChapter 8:
    The pneumatic cylinder – part 2
    • ISO 21287 | compact cylindersChapter 8:
    The pneumatic cylinder – part 2
    • UNITOP | compact cylindersChapter 8:
    The pneumatic cylinder – part 2
    The HAFNER ISO 15552 cylinders
    The standard ISO 15552 is valid since 2004. The previous and very closely related standard was
    ISO 6431 (1992 – 2004).
    The standard defines piston diameters (ø32…ø320 mm), maximum pressure (10 bar), and distinct features and
    dimensions, as well as standard accessories.
    Thus any accessories are also mostly interchangeable.
    The ISO 15552 cylinders in the HAFNER range have the type number DIL and DIP (for products with a runthrough piston rod: DBL and DBP)
    DIL cylinder
    The more economic solution since little material is used for the profile. Easy to clean.
    Any sensors have to be assembled with special fixing elements.
    DIP cylinder
    Switches can go into the groove, easy assembly, no additional parts.
    Since 2016 HAFNER have been offering another range of economically-priced profile cylinders
    called “H-series”.
    HIF cylinder
    Switches can go
    into one of the four
    grooves of the
    profile tube.Chapter 8:
    The pneumatic cylinder – part 2
    Materials used in an ISO 15552 cylinder of the D-series:

Description Material

1. Cylinder cap Aluminum, anodized
2. Fixing nut for piston Steel, nickel plated
3. O-Ring (seal between piston and piston rod ) NBR
4. Magnet Ferromagnetic material
5. Piston seal Polyurethane
6. Piston Techn. polymer (or aluminum)
7. Tube Aluminum, anodized
8. Guide Techn. polymer
9. O-Ring (seal for cushioning) NBR
10. Screw (for cushioning) Steel, nickel plated
11. Mobile seal (for cushioning) Polyurethane
12. Cylinder head Aluminum, anodized
13. Screws Steel, nickel plated
14. Seal for piston rod Polyurethane
15. Piston rod Chromed steel or stainless steel
16. O-Ring (seal between head and tube / cap and NBR
17. Covers PA
18. Bushing / bearing for piston rod Sintered bonze
19. Nut at piston rod Steel, nickel platedChapter 8:
    The pneumatic cylinder – part 2
    Due to high speeds, long strokes and high frequencies the seals can wear out faster than other parts. Therefore
    we offer spare-part kits for the cylinders. The spare-part kits contain all potentially worn-out parts.
    Repair kits for cylinders types DIL, DIP, DBL and DBP have the order code DIR.
    Standard ISO 15552 also defines the dimensions of the fixed accessories. Therefore any accessories by
    different manufacturers will be mostly compatible.Chapter 9:
    The basics of air preparation
    Right of authorship: the content of the training (wording, drawings, pictures) are owned by the author. Any utilization except for
    individual use is allowed only after permission of the author.
    Compressed air
    CAUTION! The quality of the compressed air in use is substantially important for the safe operation
    and durability of the pneumatic system.
    Air consists of: Nitrogen (N2) 78,09 %, Oxygen (O2) 20,95% and Argon (Ar) 0,93 %. 0,03 % of the volume is
    made up by other gases ,such as CO2, Methane and various noble gases. Air can be polluted by sulfurous
    gases, carbon-monoxides and dirt, damps, or particles.
    When producing compressed air (compressing the environmental air), and when transporting it through the
    tubes, other harmful elements may enter.
    In order to define the quality of compressed air, there are standardized purity classes.
    Purity classes for compressed air in accordance to ISO 8573-1
    Compressed air is classified. The three most important elements of pollution are particles, water and oil.
    They are classified in accordance to their degree of concentration within the air and displayed as follows:
    ISO 8573-1:2010 [A:B:C]
    • A – particles | 0 … 8, X
    • B – water | 0 … 9, X
    • C – oil | 0 … 4, X
    In case an element is displayed as class X (= an element with a high concentration), its amount or the degree of
    concentration needs to be put in round brackets. The following example shows the quality of air where the water
    concentration is at Cw 15 g/m3. Therefore we indicate its purity as follows:
    ISO 8573-1:2010 [4:X(15):3]Chapter 9:
    The basics of air preparation
    Purity classes for compressed air in accordance to ISO 8573-1
    ISO 8573-1:2010
    Class
    Particles Water Oil
    Maximum number of particles of
    the following size [µm] / m³ of
    compressed air
    Concentration
    Pressure dew
    point
    °C
    Content of
    liquid
    [g/m3]
    Total content
    (liquid, aerosol,
    gas)
    [mg/m3]
    0,1 … 0,5
    µm
    0,5 …1 µm 1 … 5 µm [mg/m3]
20. By definition of the user, less contamination than class 1
21. ≤ 20 000 ≤ 400 ≤ 10 – ≤ -70 – ≤ 0,01
22. ≤ 400 000 ≤ 6000 ≤ 100 – ≤ -40 – ≤ 0,1
23. – ≤ 90 000 ≤ 1000 – ≤ -20 – ≤ 1
24. – – ≤ 10 000 – ≤ +3 – ≤ 5
25. – – ≤ 100 000 – ≤ +7 – –
26. – – – ≤ 5 ≤ +10 – –
27. – – – 5 … 10 – ≤ 0,5 –
28. – – – – – 0,5 … 5 –
29. – – – – – 5 … 10 –
    X – – – > 10 – > 10 > 5
    In normal pneumatic applications the following air quality is sufficient: ISO 8573-1:2010 [7:4:4].
    According to the ISO norm, the permitted degrees of pollution are:
    • Particle concentration 5-10 mg/m3
    • Dew point less than 3 °C
    • Oil concentration max. 5 mg/m3
    For specific applications or in extreme environments (e.g. railway application in cold climates), a higher air purity
    might be required.Chapter 9:
    The basics of air preparation
    Basics regarding the generation and preparation of compressed air
    When generating compressed air, it is important to ensure it to be as oil-free as possible at the lowest possible
    cost. The preparation of compressed air has the same economical aspect.
    It is possible to generate compressed air of a high quality – i.e. oil-free or with reduced oil-content – with
    compressors that work both with and without lubrication if a sound air preparation has been established.
    The environmental air and its quality
    The air’s quality highly depends on external, environmental factors. The concentration of hydro-carbonates
    due to industry or traffic can reach levels of 4-14 mg/m3.
    In factories the oil content can exceed 10 mg/m3 because of coolant and lubrication fluids in the machinery.
    Moreover there are other polluting elements such as sulfur dioxide, soot, metals, dust and humidity.
    How to define „oil-free“ compressed air?
    According to ISO 8573-1 compressed air can be called “oil-free“ when the content of oil (including oil dust) is
    less than 0,01 mg/m3. That is about 4 % of the oil content in normal air, so it is hardly detectable. You can find
    such requirements for very high air purity e.g. in the food and pharmaceutical industry as well as the electronics
    industry (manufacture of wafers etc.).
    Where does humidity come from?
    There is always humidity in the environmental air. The degree of the humidity depends on temperature and
    air-pressure. The warmer it is, the higher the ability of air to hold water. At higher pressure that ability weakens.
    Absolute humidity: amount of water in
    1 m3 air.
    Max. humidity (saturation): highest
    possible amount of water in 1 m³ air at
    the given temperature and pressure.
    Relative humidity: the degree of
    humidity in relation to max. humidity
    (%) at this temperature.Chapter 9:
    The basics of air preparation
    Formula:
    Relative humidity =
    Absolute humidity
    Maximum humidity ∙ 100 (%)
    The table below displays the max. humidity values of air (saturation values) at different temperatures:
    Temperature (°C) -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40
    Water content
    (g/m3) 0,4 0,7 1,1 1,6 2,4 3,4 4,8 6,8 9,4 12,8 17,3 23,1 30,4 39,6 51,2
    If the humidity becomes higher than 100% relative humidity the excess water is released. The temperature at
    which water is released at the given air-water concentration is called the dew point.
    Water is released when the temperature goes down and/or when air pressure rises. This is exactly what
    happens in the compressor as well as in the air-cooler. The water that is released forms the so-called
    condensate.
    The drying of compressed air
    When air gets cooler, it releases water.
    Example:
    A screw compressor working at a temperature of 20°C, at sea-level, has a suction capacity of 10 m3per
    minute; the relative humidity of the environmental air is 60 %.
    Looking at the table above, we can see that at 20°C 100% humidity = 17.3 g water / m3air. So we can deduct
    that 60% humidity = 10.4 g water / m3
    Thus the 10 m³ contains 104 g of water.
    At a compression ratio of 1:10 (10 bar), the compressor generates 1 m³ of compressed air per minute (10 m3
    environmental air = 1 m3 compressed air).Chapter 9:
    The basics of air preparation
    During compression the air’s temperature rises to around 80 °C. At this temperature it can hold 290 g water / m3
    air (referring again to the table above). Therefore its relative humidity is at only 36% (104 / 290 = 36%). The
    air is relatively dry and produces no condensate.
    A cooler after the compressor cools the compressed air down from 80 °C to approx. 35 °C. At 35°C the air can
    only hold 39.6 g / m3, though there are 104 g of water inside each m3. So 64 g / m3 will be released. This
    means we have 64 g of excess water every minute the compressor operates. This translates (x 60 x 8) into
    31 liter of condensate after an 8 hour shift.
    In order to have fairly safe working conditions, this condensate needs to be removed. The drying ( =
    cooling) of the generated compressed air is an essential part of the generation and preparation of
    compressed air.
    CAUTION! Without properly drying the air you will find a lot of condensate in the air-tank as well as in your pipelines, machinery and many other places.
    CAUTION! The standard filters of an FRL-unit (50 … 0,01 Mikron), do not influence the content of water.
    They are made for filtering particles. The water you will find in the condensate drain of a filter consists only of a
    few drops. It is irrelevant in comparison to the amounts of water mentioned before.
    How to dry the air?
    The drying of compressed air in an industrial environment is usually achieved with one of the following methods:
    • Deliquescent dryer
    A deliquescent dryer typically consists of a container filled with hygroscopic material that absorbs the
    water. Advantage: No additional energy is required. Disadvantage: The hygroscopic materials have to be
    replaced regularly.
    • Desiccant dryer
    Also called twin tower dryer or adsorption dryer. The air flows through a desiccant material such as silica
    gel. The gel’s ability to keep water is limited, but can be easily reset by blowing the water out (“purging”
    the gel). No additional energy is required here either, but there is a loss of compressed air due to the
    purge. Large equipment is needed for air flows at high speeds.Chapter 9:
    The basics of air preparation
    • Membrane dryer
    First the air has to be filtered with a high quality coalescing filter, then the air passes through a center
    bore of a hollow fibre in a membrane bundle. Dryer air is floating outside the membrane. This leads to an
    exchange of vapor. Disadvantage: the flow is limited to around 1000 l/min.
    • Refrigerated dryer
    Refrigerated drying is based on the principle that colder air can hold less water. The air passes a heatexchanger that is cooled to around 3°C. The cooled-down air loses water as well as oil, both of which are
    collected. After drying the air is filtered.
    Components of a refrigeration dryer
30. Air-in and air-out
31. Air-to-air head exchanger
32. Air-to-refrigeration heat exchanger
33. Condensate separator
34. Condensate drain
35. Cooling compressor
36. Cooling ventilator
37. Cooling medium injectorChapter 9:
    The basics of air preparation
    Why is air-preparation necessary?
    You could look at a compressor as a big vacuum cleaner. It sucks in everything from the environment. When
    generating compressed air, all the environmental elements of pollution are concentrated. Everything is fed into
    the pneumatic system.
    FRL-units are an important element of the pneumatic system. With these units the air can reach the
    required quality since they have filters for cleanness, lubrication for oil content and can manage pressure.
    Well-processed air does not only ensure a safer workspace but also increases the durability of the equipment.
    Air preparation equipment consists of:
    • Filters
    • Pressure regulators
    • Lubricators
    • Switch-on and starter valves
    • Distributors, pressure switches
    We can categorize them by design, size, flow rates and port size. There is a wide range available, from port size
    G1/8″ to G3″.Chapter 9:
    The basics of air preparation
    The following pictures show a selection of the most common elements:
    Filter Regulator
    Lubricator Filter-Regulator UnitChapter 9:
    The basics of air preparation
    FRL-unit, consisting of a filter, a regulator and a lubricator
    Modular FRL-units offer a high degree of flexibility to the user since these individual products can be
    assembled easily into a whole unit.Chapter 10:
    Air Preparation Units
    Right of authorship: the content of the training (wording, drawings, pictures) are owned by the author. Any utilization except for
    individual use is allowed only after permission of the author.
    Filtering of compressed air
    The task of the filter is to filter out particles and to remove the condensate released by the compressed air.
    CAUTION! Filters (50 to 0,01 Micron) have no influence on humidity, they filter particles depending on the
    fineness of the filter elements. The water that is found in the condensate drain only consists of drops and is
    relatively irrelevant.
    Sometimes several filters are necessary in a system because of different requirements:
    • Pollution from the pipeline or condensate released during transportation has to be removed before
    reaching individual equipment.
    • Different pieces of control or regulating equipment require different air quality.
    • For specific applications (e.g. the packaging of food) standard filtration is insufficient. Activated-carbon
    filters are required. The air used in these filters has to be pre-filtered by fine-filters.
    In pneumatics cyclonic filtration is often used to separate particles and condensate from the medium.
    Cyclonic separator
38. Filter bowl
39. Filter element
40. Body
41. Condensate drain
    A high-speed rotating (air) flow is established within a
    cylindrical or conical container, called a cyclone.
    Due to the centrifugal force, particles and condensate fall
    towards the outside and drop to the bottom.
    In addition, the medium flows through a filter element that
    catches smaller particles. The fineness of the filter element
    determines the max. size of particles. Polluted condensate can
    be drained from the bottom of the bowl.Chapter 10:
    Air Preparation Units
    An automated drain valve works as a floating exhaust valve. As soon as the condensate reaches a certain level,
    the valve opens and drains the bowl.
    Automated condensate drain
42. Float sensor
43. Body
44. Spring
45. Closing element
46. Bowl
47. Port for condensate – manual override
    How it works:
    Without pressure the closing element (4) is in an
    open position. The condensate that is
    concentrated at the bottom of the bowl (5) is
    drained.
    At an operating pressure of around 1,5 bar the
    valve closes the drain.
    In case that during operation (pressure in the filter
    element) the condensate rises high enough to loft
    the floater, the valve opens the drain and the
    condensate is blown out of the bowl. Thus the level
    of condensate is lowered and the drain closes
    again.
    Automated drains can also be operated manually.
    By turning the knob at the bottom, the drain is on
    manual mode and the condensate is blown out of
    the bowl (if there is air pressure) / drips out of the
    bowl (without air pressure).Chapter 10:
    Air Preparation Units
    Depending on the requirements inside the pneumatic system there are different filter elements offering different
    degrees of fineness and materials.
    In pneumatics we typically use filter elements with a finesses of 5 to 50 µm.
    In order to reach an air quality according to ISO 8573-1:2010 [7:4:4], the following is required:
    • Concentration of particles: 5-10 mg/m3
    • Filter fineness: 20-50 µm
    In case of higher requirements, we recommend standard ISO 8573-1:2010 [6:4:4] which is still common in
    pneumatics:
    • Concentration of particles: Maximum 5 mg/m3
    • Filter fineness: 5 µm
    Based on make and fineness of the filter element, we differentiate between filters:
    • Classic filter unit
    o Filter fineness: 5 µm, 20 µm, 50 µm
    o Material: sintered PE, sintered bronze on request
    • Pre-filter unit
    o Filter fineness: 0,3 µm
    o Material: cellulose-acetate
    • Fine-filter unit
    o Filter fineness: 0,01 µm
    o Material: glass fibre with acetate
    • Activated-carbon filter
    o Material: activated-carbonChapter 10:
    Air Preparation Units
    Classic filter unit
    (KFIL)
    Filter fineness: 5 µm
    Pre-filter unit
    (KPFI)
    Filter fineness: 0,3 µm
    Oil content: 0,1 mg/m3
    Class 2 (ISO 8573-1)
    Fine-filter unit
    (KCFI)
    Filter fineness: 0,01 µm
    Oil content: 0,01 mg/m3
    Class 1(ISO 8573-1)
    Activated-carbon filter unit
    (KAFI)
    Filter fineness: n.a.
    Oil content 0,005 mg/m3
    Class 0 (ISO 8573-1)
    Durability of the filter elements
    Filter elements need to be exchanged on a regular basis since their flow will be reduced
    over time due to pollution. The loss of air-pressure can be detected by measuring the
    differential pressure in front of and behind the filter.
    p = p1 – p2
    Measuring differential pressure with a gauge:
    The dirtier the filter element, the larger the pressure drop inside the filter. The pressure
    difference is measured between 0 and 0,5 bar, which shows how much blockage there is
    in the filter element.Chapter 10:
    Air Preparation Units
    Pressure regulation with a regulator
    Normally the network supplies pressure between 6 and 10 bar, which can vary depending on the rate of air
    consumption.
    In order to use compressed air efficiently, the required pressure should be set for each piece of equipment with
    an individual pressure regulator. The individual pressure can only be lower than the pressure supplied by the
    network.
    It is the task of the pressure regulating valve to hold the level of the output pressure on a constant level,
    regardless of input pressure or fluctuations in air consumption.
    We differentiate between regulators with secondary venting and regulators without secondary venting.
    Regulators with secondary venting can let out excess pressure on the secondary side, e.g. when the
    pressure P2 is reduced by the operator or when the pressure is increased by the equipment (high load on a
    large cylinder).
    Regulators without secondary venting are usually used when the medium is not supposed to be released
    into the atmosphere.Chapter 10:
    Air Preparation Units
    Regulator, with secondary venting
48. Body – spring casting
49. Knob to set pressure
50. Spring
51. Diaphragm
52. Seat with valve disc
53. Counter-pressure spring
54. Body
    Essential for the pressure regulation is the diaphragm
    (4). On the surface below the diaphragm, the
    secondary pressure is in effect, against which the force
    of the set spring (2) works from the top.
    If the force of the air pressure is weaker than that of the
    spring, the diaphragm is pushed down and the valve rod
    (5) is opening the poppet valve. Pressure is rising.
    In case there is less consumption, pressure below the
    diaphragm builds up. The force of the air is larger than
    that of the spring, and the valve disc is gradually closing,
    eventually fully closing the valve seat.
    If secondary pressure exceeds the pressure that was
    set, the diaphragm is pushed upwards and the
    secondary exhaust is opening up (if the regulator is
    equipped with a secondary vent).
    Secondary pressure can be displayed by a pressure
    gauge.
    CAUTION! Pressure regulation in pneumatics is a regulation of volume. The amount of compressed air
    behind the regulator needs to be large enough to build up an air pressure that is the same as set at the regulator
    (off-setting the force of the spring in the regulator). If the pressure drops, more air is fed into the system behind
    the regulator. There must be a balance between the force of the air-pressure and the force of the spring.Chapter 10:
    Air Preparation Units
    Lubricating the compressed air
    Neither control-elements nor actuators are separately lubricated in a pneumatic system. In order to avoid wearout, lubrication can help. Unnecessary friction also increases energy consumption.
    The goal of the manufacturers of the components is to design products that do not require any individual
    lubrication. This can be realized by selecting the right materials, choosing the right seal system, reducing
    friction, or supplying the product with sufficient (life-long) lubrication when initially sold. For this kind of
    lubrication, special types of grease are available. They are designed to constantly stay in the valves or cylinders.
    In order for the lubricant to avoid washing-out, the air needs to be dry since water has a negative effect on it as
    well.
    The same washing-out effect is true when lubricators are used. Therefore, if lubricators are in use, they
    must not run dry!
     The eternal question: “Should lubricators be used or not?”
    Answer: It always depends on the application!
    In certain industries (e.g. food industry) lubrication is not allowed at all. In other industries with very big cylinders
    and strong forces, lubrication can be really beneficial, especially for the durability of the actuators.
    The lubricators in pneumatic systems use the Venturi principle.
    A pressure difference is generated by forcing the
    compressed air through a jet. Behind the jet the
    pressure is lower.
    This pressure difference sucks oil from the container
    into the air stream where it is dispersed very finely.
    The same principle is used in a carburetor of a car
    running on petrol.Chapter 10:
    Air Preparation Units
    Lubricator
55. Oil container
56. Dosing unit
57. Body
58. Knob to activate sucking function for refill.
    Some lubricators have a devise that enables oil to
    be sucked in while the equipment is pressurized
    with the aid of a vacuum.
    At the bottom of the body, a tube has to be
    connected. The end is to be held into the oil. Press
    the button (4) and the lubricator is refilled with oil.
    Air preparation units – pictures and ISO symbols
    Filter unit
    Pressure regulator
    LubricatorChapter 10:
    Air Preparation Units
    Filter regulator with pressure gauge
    FRL-unit (filter, regulator, lubricator and
    pressure gauge)
    Manually-actuated main switch-on
    valve, 3/2-way
    3/2-way solenoid valve with manual
    override
    Soft starter valve
    Soft starter valve with electric actuationChapter 10:
    Air Preparation Units
    CAUTION! It is insufficient to have only one filter and one pressure regulator for the entire system. Due to the
    volatile consumption of compressed air, the different pieces of equipment need individual air preparation
    (pressure, sometimes also different air quality, filtration / lubrication).
    We recommend to locally prepare the compressed air for the different pieces of your equipment. This reduces
    wear-out and increases the durability of machines and equipment.
    There are many products to choose from:
    Further information can be found in the category “FRL-units” on our website.Chapter 11:
    Valves and Actuators with the
    NAMUR-interface
    Right of authorship: the content of the training (wording, drawings, pictures) are owned by the author. Any utilization except for
    individual use is allowed only after permission of the author.
    Valves with NAMUR-interface to control process valves
59. Pneumatic actuation of process valves
    Process valves can be actuated manually, electrically, pneumatically and hydraulically. Often times pneumatic
    actuators are in use when it comes to automated process valves. They are mostly either linear actuators
    (pneumatic cylinders) or rotary actuators.
    .
    Whether it’s a linear or rotary actuator, the
    pneumatic automation of process valves is
    popular.
    There are distinct advantages of pneumatic
    actuators in comparison to electric ones:
    • High torque
    • Low maintenance
    • Few spare parts
    • High durability
    • High reliability
    • Useable in explosion hazardous
    environments
    • Inexpensive
    As the field of applications and types of
    process valves is extremely wide, we
    will not cover that.
    Instead we will focus on the
    pneumatic actuation and control of
    rotary actuators with NAMURinterface.Chapter 11:
    Valves and Actuators with the
    NAMUR-interface
    A pneumatically automated process valve has three main parts:
60. Process valve
    Part of the pipe-line system, e.g.
    ball valve or butterfly valve.
61. Pneumatic rotary actuator
    Opens and closes the process
    valve.
62. Pilot valve
    (with NAMUR-interface)
    Directional control valve for
    control of pneumatic rotary
    actuators.
    Further important elements can be:
    • Switch-box to feed the position of the process valve back to a central command,
    • Manual override – clutch for emergencies or
    • Positioner, replacing the switch-box and mostly including the control valve.
63. Pneumatic rotary actuators
    The design and dimensions of rotary actuators differ from manufacturer to manufacturer. The two most popular
    designs are either Scotch-Yoke or Rack and Pinion actuators. We will introduce you to the Rack and Pinion
    actuator with more detail.
    The 2 piston rods of the 2 pistons inside the
    actuator are shaped like racks. Compressed air
    is driving them. The racks drive a pinion which is
    linked via a shaft to the process valve and opens
    or closes it.Chapter 11:
    Valves and Actuators with the
    NAMUR-interface
    The selected size of the actuator depends on the force required to open and close the process valve. Usually the
    manufacturer indicates the maximum torque the actuator offers at a specific pressure.
    There are two versions of linear actuators:
    • Double-acting actuators
    • Single-acting actuators (with mechanic spring return)
    In double acting actuators – depending on the direction required – compressed air flows to the outside or to
    the inside of the two pistons. This can be easily controlled by using 5-way directional control valves (5/2-way
    for fully opening and closing the process valve, 5/3-way if intermediate positions are required).
    In single-acting actuators, the reset to basic position is realized by using packs of mechanical springs.
    Two packs of springs are positioned on the outside
    of the actuator, pushing the pistons into the middle
    position. The area the springs are in is called the
    “spring chamber”.
    As soon as the actuation side of the actuator is
    exhausted, the springs push the pistons together,
    which turns the pinion and (depending on what is
    required) opens or closes the process valve.Chapter 11:
    Valves and Actuators with the
    NAMUR-interface
    There are standards for the contact interfaces of a rotary actuator, e.g.:
    • Contact interface to the control valve | VDI/VDE 3845 (NAMUR)
    • Contact interface to the process valve | ISO 5211 | DIN 3337
    VDI/VDE 3845 (NAMUR)
    Interface on the actuator that
    allows to flange directly a
    control valve with NAMURinterface.
    ISO 5211 | DIN 3337
    Connection to the process
    valve.Chapter 11:
    Valves and Actuators with the
    NAMUR-interface
64. The NAMUR-interface
    NAMUR-valves are control valves which offer an assemblage interface according to the standard
    VDI/VDE 3845.
    NAMUR-valves are different from other in-line valves as they offer two ports on the flat side of the valve.
    In addition, there are holes for fixing the valve onto the actuator.
    The drawing below shows a single solenoid 5/2-way valve with an interface according to NAMUR. The
    dimensions of the 1/4” -interface, among others, are shown as well.
    Type: MNH 510 701.
    Besides the 1/4“-interface there is also one for larger actuators:
    • G 1/4″- interface NAMUR valve | description: [NAMUR 1/4″] or NAMUR 1
    • G 1/2″- interface NAMUR valve | description: [NAMUR 1/2″] or NAMUR 2
    Dimensions of the NAMUR interfaces on the actuator
    T* D1 D2 M
    NAMUR 1/4″ G 1/8” / G 1/4″ 32 24 M 5
    NAMUR 1/2″ G 3/8” / G 1/2″ 45 40 M 6
    The hole M is typically used for mounting a setscrew onto the rotary cylinder,
    which fits into the blind bore of the valve and defines its operating direction.
    The hole R is usually used for fastening screws.
    NAMUR-Interface
    VDI/VDE 3845Chapter 11:
    Valves and Actuators with the
    NAMUR-interface
    The picture displays a MNH 510 701, which is a
    5/2-way single solenoid NAMUR-valve. It is
    used to control a double-acting actuator.
    Ports 2 and 4 are on the side of the valve. The
    ports are sealed towards the actuator with
    O-rings.
    Port 1 ( = supply) and ports 3 and 5 ( = exhausts)
    are on the flat side of the valve (shown here on the
    top).
    The picture displays an MNH 310 701, which is a
    3/2-way single solenoid NAMUR-valve. It is used
    to control a single-acting actuator.
    Ports 2 and one port 3 are on the side of the valve.
    The ports are sealed towards the actuator with
    O-rings.
    Port 1 ( = supply) and the other port 3 ( = exhaust)
    are on the flat side of the valve (shown here on the
    top).Chapter 11:
    Valves and Actuators with the
    NAMUR-interface
    A normal 3/2-way inline valve has 3 ports. The 3-way NAMUR-valve on the photo however has 4, which
    you can also see on its ISO symbol. WHY IS THAT?
    Single-acting actuators (the ones with springs)
    have 2 ports as well. One is connected to the
    actuation side, the other to the spring chamber.
    In order to avoid air from the atmosphere (which might
    be wet, polluted or dirty) to enter the spring chamber, it
    should be ensured that (potentially cleaner) process air
    enters it instead in order to avoid corrosion of the
    springs.
    That is why in process automation, we aim towards an air recirculation into the spring chamber, also called a
    “purge”.
    When the actuation side of the actuator is exhausted (3/2-way valve n.c. in
    standard position), the actuation chambers are gradually becoming smaller and
    the spring chambers larger as the springs expand. The 3/2-way NAMUR-valve
    feeds part of the process air into the spring chambers before it is used to
    expand the actuation chambers. The excess air exhausts through the external
    (second) port 3. This function is indicated in red in the ISO symbol.
    By feeding process air into the spring chambers, we want to reduce pollution inside the actuator due to dirt,
    dust, mist, moisture etc. that might have been sucked into the spring chambers and thus avoid corrosion of the
    springs.Chapter 11:
    Valves and Actuators with the
    NAMUR-interface
65. HAFNER valves with NAMUR-interface
    HAFNER Pneumatik offers a uniquely wide range of valves with NAMUR-interface, as well as a range of
    accessories.
    • Solenoid valves | 3/2- (n.c. / n.o.), 5/2- and 5/3-way
    • Pneumatically actuated valves | 3/2-, 5/2- and 5/3-way
    • Hand lever valves | 3/2-, 5/2- and 5/3-way
    • Everything mentioned above both in NAMUR 1 and NAMUR 2
    • Numerous products made of stainless steel, for cold and for explosion-hazardous environments
    • Flow-regulator plates
    • Quick-exhaust valves and „purge-blocks“
    • Numerous safety valves (manually, pneumatically or electrically actuated)
    • Plates and accessories
    HAFNER does not only offer standard products but also offers:
    • NAMUR Flex | 5/2-way valve with a kit to convert it into a 3/2-way valve with air recirculation
    • Stainless steel valves | made from 1.4404 (316L)
    • Low temperature valves | -50°C to +50°C
    • High temperature valves | -20°C to +80°C
    • BSP or NPT ported
    • ATEX-certified products for explosion-hazardous environment
    • Specially selected materials | brass-free products
    • Products with air springs or combined springs
    • Products with swapped ports
    • Products with different types of manual overrideChapter 11:
    Valves and Actuators with the
    NAMUR-interface
    Values of the standard Hafner 5/2-way NAMURvalve type MNH 510 701:

• Orifice size : DN 7 mm
• Flow: 1250 l/min
• Operating pressure : 2 – 10 bar
• Power consumption: 3 W / 5 VA
  (in combination with standard coil MA 22)
• Ports 1, 2, 3: G 1/4″
• NAMUR 1: 1/4″
  MNH 511 701: same valve, but with a combined
  mechanical and pneumatic spring return.
  MNH 510 701 MNH 511 701
  Standard sizes of HAFNER NAMUR-valves:
  Series 701| orifice: 7 mm | flow: 1250 l/min | ports: G 1/4″ – 1/4″ NPT | NAMUR 1, 1/4″
  Series 101| orifice: 10 mm | flow: 2250 l/min | ports: G 3/8″ | NAMUR 1, 1/4″  maximized air-flow
  Series 121| orifice: 12 mm | flow: 3000 l/min | ports: G 1/2″ – 1/2″ NPT | NAMUR 2, 1/2″
  Conforming to standards, the flow measurement is shown as nominal flow in [l/min]. Nominal flow: at p1= 6 bar,
  p = 1 bar, stream-value of the compressed air (l/min).Chapter 11:
  Valves and Actuators with the
  NAMUR-interface
  Besides maximum flow of 1.250 l/min in a compact design there are 10 more
  competitive advantages of the Hafner NAMUR-valves series 701.

1. PA fixing nut, which protects the solenoid system from wetness and moisture.
2. Coil MA 22 fully covered with PA or Epoxy (on request), 360° rotatable. Others (Ex-versions) available on
   request.
3. Brass operator tube, including O-ring to protect solenoid system from wetness from the bottom.
4. Head made from PA.
5. Brass manual override for turning; other versions and materials (e.g. stainless steel) on request.
6. Spool made of stainless steel; other inner parts are: brass, POM, NBR, FKM.
7. Fixing screws, stainless steel.
8. Body, anodized aluminum.
9. End-cap made from brass.
10. Unique sealing system, the HAFNER swimming O-Ring.Chapter 11:
    Valves and Actuators with the
    NAMUR-interface
11. Selection of Hafner NAMUR-Accessories
    MNH 350 701: HAFNER NAMUR-Flex valve
    HAFNER‘s MNH 350 701 is a single solenoid 5/2-way NAMUR -valve,
    electrically actuated with air spring return. It is used to control doubleacting actuators (with the same function as the MNH 510 701).
    Adding the Flex-Plate type FP 701, the valve is converted into a 3/2-
    way NAMUR-valve with air recirculation for the spring chamber (purge).
    The MNH 351 701 offers a combined spring return.
    MNH 350 701
    works like a 5/2-way valve
    MNH 350 701 + Flex plate
    works like a 3/2-way valve
    This valve is also available both in stainless steel and NPT ported.
    FP 701Chapter 11:
    Valves and Actuators with the
    NAMUR-interface
    DRN…: Flow regulator plates
    The Hafner flow regulator plates offer a very precise control of the openingand closing speed of actuators. Regulation possible with 3- way and 5-way
    valves.
    Additionally the DRN offers the only possibility to regulate the forwardand backward-stroke of single-acting actuators, which is controlled by a
    3-way valve, independently and precisely.
    Two different types of actuation are available:
12. DRN _ 601: to be operated manually
13. DRN_ 611: to be operated with a screwdriver
    Plates are available with 1/4“ and 1/2″ NAMUR-interface.
    Assemblage between NAMUR pilot-valve and actuator or with threaded
    plate type GPN-1/4” for direct piping. DRN 611
    DRN 601
    DRN 3 … for single-acting
    actuators
    DRN 5 … for doubleacting actuatorsChapter 11:
    Valves and Actuators with the
    NAMUR-interface
    UB 701: NAMUR Air-recirculation block
    The air-recirculation block guarantees, that only
    exhausting air from the actuation chamber is going
    into the spring chamber. No ambient atmosphere is
    sucked-in. It is used in combination with single-acting
    actuators when they get controlled by remote installed
    3/2-way valves e.g. from a control cabinet.
    The integrated non-return valve makes sure, that no
    ambient atmosphere can enter the actuator.
    Block is designed for actuators with 1/4“ NAMURinterface. Port 1 for air-pressure supply G 1/4”
    threaded. 2 x G 1/4” exhaust ports.
    Further information about our NAMUR-valves and accessories can be found in our catalogue
    “Competence in Valve Automation”.Chapter 14:
    Solutions for challenging environment:
    Part 1: Cold, Warm, Moisture / Dust
    Page 1
    Right of authorship: the content of the training (wording, drawings, pictures) are owned by the author. Any utilization except
    for individual use is allowed only after permission of the author.
    In the following two chapters we will have a look at the challenges we face in different environments
    and the solutions we have available. Chapter 14 and 15 cover the following challenges:
14. Cold environment
15. Warm environment
16. Wet and polluted environment: the IP protection
17. Chemical influences or corrosive environments like seawater (chapter 15)
18. Cold Environment
    In chapter 2 we already discussed air preparation and drying. At temperatures below 0 °C, properly
    prepared and dried air is essential. It is important to consider the dew point.
    The dew point is the temperature to which a given parcel of air must be cooled, at constant
    barometric pressure, for water vapor to condense into water. The relative humidity at the dew point
    is 100%. In the area below 0° C the dew point is also called frost point.
    As soon as air becomes compressed, the relative amount of particles in the air increases, also the
    water particles, this means water falls out. Therefore the air-pressure has a big influence.Chapter 14:
    Solutions for challenging environment:
    Part 1: Cold, Warm, Moisture / Dust
    Page 2
    Keep in mind: The dew point has to be 15°C under the environmental temperature, otherwise the
    air will lose its ability to keep the water when being compressed. Water in the valve / actuator would
    then freeze and lead to leakage or malfunction.
    In order to reach the dew point it is important to use an appropriate dryer. We recommend the use of
    an adsorption dryer. Check the dew point of the dryer which must be at least 15°C under the
    ambient temperature.Chapter 14:
    Solutions for challenging environment:
    Part 1: Cold, Warm, Moisture / Dust
    Page 3
    Example:
    If we are declaring in our manual / catalogue that the dew point has to be 15° C below the current
    environment temperature signifies, that the relative humidity of the air-pressure has to be distinctly
    lower than 100%. As a result freezing as well as spread of condensate is avoided.
    • Environment temperature = 25° C
    • Dew point at 100% humidity = 25° C
    • Required dew point = 25° C – 15° C = 10° C
    • this means a relative humidity of ~ 50%
    Don’t lubricate yourself! As a special lubrication is being used inside the HAFNER low temperature
    valves, the usage of other lubricants or oils might lead to malfunction.
    Please note that in most of our low temperature valves we use lip seal rings made from PUR
    (Polyurethane). Due to the geometry of these seals, the pressure connection is only possible at
    port 1. We can optionally use a different type of sealing system where pressure can be connected to
    other ports as well. For further information, please ask the manufacturer.
    Please note that below -40 °C, the valve leakage may increase to 10 cm3/minute.Chapter 14:
    Solutions for challenging environment:
    Part 1: Cold, Warm, Moisture / Dust
    Page 4
    The Hafner low temperature valves carry the suffix “TT” or “AIR TT” (optional sealing system):

• BR 311 701 TT
• HV 511 701 TT
• MH 510 701 G TT
• MNH 510 701 TT
  In particular, the choice of material for the sealing elements is crucial in low-temperature
  applications. PUR, silicones and low-temperature NBR are particularly suitable. But not only the
  material, but also the geometry of the seals plays a crucial role.
  The components of cold-resistant cylinders are usually stainless steel, anodized aluminium,
  sintered bronze or brass. Seals are made from polyurethane and NBR.
  Below -20 °C the NBR gasket hardens and loses its sealing ability, so the cylinder starts to leak.
  Cylinders used at high temperature are usually made with FKM seals, which however cannot be
  used below 0 °C.
  Our air preparation units are generally usable till -10 °C, so it is important to place them in a
  location that keeps them from getting any colder than this. It is important not to let the moisture
  collected in the filter cup freeze as the ice may crack the cup. It is therefore beneficial to use the
  automatic version. Some selected FRL-units are available for -40° C on request.
  It is important that not only our main components such as valves and cylinders withstand extreme
  weather, but the ‘transmission elements’ too. A type of pneumatic tube must be used which due to
  its material, can withstand minus degrees. The table below illustrates the temperature range for
  some tubes and fittings.
  Product Material Temperature range
  Tube
  Teflon -200 °C to +260 °C
  Polyamide -60 °C to +100 °C
  Polyurethane -35 °C to +60 °C
  Polyethylene -10 °C to +40 °C
  Product Version Temperature range
  Fittings
  Cutting ring -60 °C to +300 °C
  Thread without O-ring -40 °C to +80 °C
  Thread with O-ring -20 °C to +80 °C
  Push-in -20 °C to +80 °CChapter 14:
  Solutions for challenging environment:
  Part 1: Cold, Warm, Moisture / Dust
  Page 5

1. Warm environment
   We face the challenge of a warm environment not only in high temperature production processes,
   but also in hot areas such as the Gulf region or applications with direct sun exposure. Especially the
   selection of the right rubber and plastic parts is essential for products in hot areas.
   Pneumatic valves are available with a wide variety of sealing materials such as NBR, PUR, FKM /
   FPM, EPDM and many more. Seals that perform well in hot environments and are most commonly
   used are FKM and FPM. These seals are identical in their raw material (fluorine-rubber /
   fluoroelastomer), the different designations are coming from different standards. While the FPM
   designation conforms to the DIN-ISO standard, the FKM seal conforms to the American ASTM
   standard.
   Remark: Many people use Viton® as a synonym for FKM / FPM, but it is a trademark by DuPont.
   Solenoid valves for high temperature applications cause major challenges to
   manufacturers
   Generally it is easier to find pure pneumatic components (no electric components on them) for hot
   environment than solenoid valves. Most of the solenoid system manufacturers limit their systems to
   50°C/+60°C as the electrical actuating of the solenoid is causing additional heat. Hafner however
   offers their solenoid valves for up to +80°C (DC-versions only) due to a special material selection.
   Non-electrical valves are available for up to +120°C.
   In case a solenoid valve is required and the environment exceeds +80°C, an option might be to take
   the solenoid out of the hot area and only leave a pneumatic valve or actuator in the hot environment.Chapter 14:
   Solutions for challenging environment:
   Part 1: Cold, Warm, Moisture / Dust
   Page 6
   When building control cabinets, be careful with putting too many solenoid valves into a small
   cabinet. Solenoids also warm-up the cabinet as most of the power consumption is transformed into
   heat. Electronic components that are also put into the control cabinet tend to suffer substantially.
   Adding a ventilation system can help to reduce the heat.
   When making the specifications for the solenoid valves, the voltage and duty cycle is an important
   aspect. You can consider as a general rule that AC magnets tend to heat up more than DC magnets.
   A duty cycle or power cycle is the fraction of one period in which a signal or system is active.
   The Hafner high temperature valves carry the suffix “HT” (solenoid valves) or “VIT” (non-electrical
   valves):
   • MH 311 015 HT
   • MNH 520 121 HT
   • P 510 701 VIT
   • HVR 520 701 VIT
   For solenoid valves the duty cycle specifies the
   maximum time of energizing the coil. The duty cycle
   is indicated as “ED” on the solenoids. Most of the
   Hafner solenoids are 100%ED what means that they
   can be energized continuously. For applications with
   100%ED we recommend the usage of FKM plunger
   seals. NBR is hardening through and therefore not
   recommended. Hafner solenoid valves have FKM
   plunger seals as a standard.Chapter 14:
   Solutions for challenging environment:
   Part 1: Cold, Warm, Moisture / Dust
   Page 7
   IP
2. Wet and polluted environment: the IP protection
   When making the specifications for solenoid valves, special attention must be paid to dust and water
   infiltration. Different electrical components are available based on the requirements. Electrical
   equipment is therefore categorized in IP-classes. IP stands for International Protection Mark.
   With this, the protection against environmental influences has been indicated on a protective case
   (housing) that protects circuits of a technical equipment. The IP classification is described in the
   IEC 60529:1989 standard.
   The protection is indicated by the 2 characters after the IP
   code.
   • The first character ranges from 0 to 6. It denotes mechanical
   protection against the penetration of solid particles.
   • The second character ranges from 0 to 9K. It means protection against liquid ingress.
   First Character Second Character
   IP Particle
   size Protection against solid particles
   IP Protection against liquid ingress
   X – X means there is no data available to
   specify a protection rating with regard
   to this criterion.
   X X means there is no data available to specify a
   protection rating with regard to this criterion
   0 – No protection against contact and
   ingress of objects
   0 None
   1 >50 mm Any large surface of the body, such as
   the back of a hand, but no protection
   against deliberate contact with a body
   part
   1 Dripping water
   2 >12.5 mm Fingers or similar objects 2 Dripping water when tilted at 15°
   3 >2.5 mm Tools, thick wires, etc. 3 Spraying water
   4 >1 mm Most wires, slender screws, large ants
   etc.
   4 Splashing of water
   5 Dust
   protected
   Ingress of dust is not entirely
   prevented, but it must not enter in
   sufficient quantity to interfere with the
   satisfactory operation of the
   equipment.
   5 Water jets
   6 Dust tight No ingress of dust; complete protection
   against contact (dust tight). A vacuum
   must be applied. Test duration of up to
   8 hours based on air flow.
   6 Powerful water jets
   6K Powerful water jets with increased pressure
   7 Immersion, up to 1 m depth
   8 Immersion, up to 1 m or more depth
   9K Powerful high temperature water jets
   IP 6 7
   Example:Chapter 14:
   Solutions for challenging environment:
   Part 1: Cold, Warm, Moisture / Dust
   Page 8
   Some examples based on the IP-list:
   IP65: Fully protected against dust AND protected against low pressure water jets from all
   directions
   IP66: Fully protected against dust AND strong water jet and immersion in water
   IP67: Fully protected against dust AND immersion in water for a limited time
   IP68: Fully protected against dust AND can be used continuously 1-3 meters under water for 30
   minutes (but individually specified by the manufacturer)
   IP69: Fully protected against dust AND can be used continuously for up to 1 hour under water
   up to 3 meters
   Please note: A higher IP-class does not automatically that the “lower” IP-class is covered as well.
   Example: a valve which is rated for IP67 is not automatically rated for IP66.
   IP-protection for Hafner solenoid valves:
   Hafner solenoid valves usually offer IP65 protection. Other protections can be offered as per the
   following table and on request.
   Standard Industrieform B
   coil and connector
   Epoxy coil, additional seals
   and connector with
   moulded cable
   Epoxy coil with M12
   connection
   IP65 IP67 IP67Chapter 14:
   Solutions for challenging environment:
   Part 1: Cold, Warm, Moisture / Dust
   Page 9
   For superior protection in very wet and dirty environments, we recommend the use of non-return
   valves in all exhaust ports. We offer exhaust protection fittings for the operator tube as well as for
   the valve exhaust ports:
   Protection for the operator tube, type MSR:
   Protection for the valve exhaust ports, type ESR:• • •Methane Natural gas Seawater
   Valve body:
   Anodized Aluminum + + –
   Stainless steel 1.4404 + + +
   Brass + + o
   PA (pilot head) + + +
   Sealing material:
   NBR + + +
   PUR o o o
   FKM/FPM + + +
   ▪ ▪ ▪420 1.4021 X20Cr13 Z20C13 KO 11
   oo o o•
   o
   •
   o
   •
   o
   •
   o• • •• ø
   •
   ▪ ø ø
   ▪ ø
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   •
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   ▪ ø
   • • ••Chapter 16:
   Explosion protection
   Page 1
   All contents of this presentation, in particular text, photographs and graphics, are copyright-protected. Please ask us if you
   would like to use the content of this presentation. Use, even in excerpts, only with the express consent of Hafner-Pneumatik
   Krämer GmbH & Co. KG.
   What is explosion protection?
   Explosion protection is a field of technology that deals with protection before explosions arise and
   that manages their effects. When dealing with substances that could react with air or oxygen, an
   explosion hazard must always be addressed if the combustible substance is present in a room with
   a particular Partial pressure or as a fine-grain dust in the air.
   A hazardous explosive atmosphere (explosive gas-air mix) is present if the proportion of the
   combustible gas or a vaporised liquid lies between the lower explosion limit (LEL) and the upper
   explosion limit (UEL). In the case of dusts, the size of the dust grains must adequately small and a
   minimum density must be present for an explosive atmosphere to exist.Chapter 16:
   Explosion protection
   Page 2
   The following diagram can assist in obtaining an initial overview of whether explosion protection
   measures may be necessary.
   Source: WikipediaChapter 16:
   Explosion protection
   Page 3
   The limit oxygen concentration (LOC) is the maximum concentration of oxygen in a mixture of a
   combustible substance with air and inert gas whereby an explosion will not occur. Along with the
   upper and lower explosion limits and the flashpoint, the oxygen concentration is an important
   characteristic value of an explosive mixture.
   Inert gases are gases that are very slow to react (inert) and so take part in only a few chemical
   reactions. Inert gases include, for example, elementary gases such as nitrogen, noble gases such
   as helium, neon, argon, krypton, xenon, and gaseous molecular compounds such as sulphur
   hexafluoride.
   The flashpoint is the lowest temperature at which, with the test conditions stipulated, a liquid
   releases flammable gas or flammable vapour in sufficient quantities that a flame appears
   immediately upon contact with an ignition source.Chapter 16:
   Explosion protection
   Page 4
   How do I ensure explosion protection?
   Explosion protection is achieved through the implementation of “integrated explosion safety” by
   means of primary, secondary and tertiary protective goals.
   Primary explosion protection Measures which prevent or restrict the formation of
   hazardous explosive atmospheres.
    Prevention of explosive atmospheres
   Secondary explosion protection Measures which prevent the ignition of hazardous
   explosive atmospheres.
    Avoidance of effective ignition sources
   Tertiary explosion protection Measures which limit the effects of an explosion to a
   harmless level.
    Design explosion protection
   Primary explosion protection should initially be implemented. If this is not possible to an adequate
   extent, secondary and tertiary explosion protection must be implemented. This is where explosionprotected devices, as dealt with in the following section, come into play.Chapter 16:
   Explosion protection
   Page 5
   Which global explosion norms and standards are relevant?
   The complex, internationally valid requirements for the use of components in potentially explosive
   applications are laid down in the most important directives and standards for the world market:
   • ATEX Directive 2014/34/EU
   • IECEx
   • CSA US – HazLoc-NA® (NEC500 and C22.2)
   • Ex EAC Not part of the Hafner product range
   A large number of Hafner products meet the requirements defined for equipment for use in
   potentially explosive areas. In contrast to the internationally recognised IECEx regulations or the
   North American regulations (HazLoc-NA®), the EU directive ATEX 2014/34/EU also includes nonelectrical equipment in the explosion protection.Chapter 16:
   Explosion protection
   Page 6
   When does a product fall under the ATEX Directive?
   The regulations relevant for the European market are found in the ATEX 2014/34/EU directive. This
   also defines when a product falls under the directive.
   What are devices in the context of the directive?
    Machines, equipment, stationary and mobile devices, control and equipping parts, as well
   as warning and equipping systems, which individually or in combination generate, transmit,
   store, measure, control, convert or consume energy or are intended for the processing of
   materials and which have their own potential ignition sources and can therefore cause an
   explosion.
   A device is subject to the directive if
    device in the sense of the directive + inherent potential ignition source
   A device is not subject to the Directive if
    not a device in the sense of the directive + inherent potential ignition source
    device in the sense of the directive + no inherent potential ignition sourceChapter 16:
   Explosion protection
   Page 7
   Differentiation is made between electrical and non-electrical devices in the
   ATEX directive.
   The approach for non-electrical devices differs from the conformity assessment procedure for
   electrical devices per ATEX 2014/34/EU. The vast majority of non-electrical devices are covered by
   a self-declaration by the device manufacturer.
   Electrical devices on the other hand must usually be certified by a notified body. The respective
   certification process required depends on the device category.
   Overview:
   Approvals process Device category 3 Device category 2 Device category 1
   Non-electrical device Self-declaration Self-declaration +
   submission of
   documentation to a notified
   body
   Testing by notified
   body
   Electrical device Self-declaration Testing by notified body Testing by notified
   body
   Pneumatic cylinders, manually and mechanically actuated valves as well as pneumatically controlled
   valves are classed as non-electrical devices. Electrically controlled valves (solenoid valves) must
   be considered with regard to both certification processes:
3. Base valve (non-electric)
4. Magnetic coil and armature system (electrical)Chapter 16:
   Explosion protection
   Page 8
   For this reason, there are two ATEX-relevant documents for solenoid valves.
   ATEX declaration of conformity ATEX certificate
   for the non-electrical part for the electrical part
   Non-electrical ATEX Electrical ATEXChapter 16:
   Explosion protection
   Page 9
   The following illustration shows how solenoid valves are sub-divided:
   Electrical part:
    Solenoid coil
    Operator system
   Non-electrical part:
    Valve bodyChapter 16:
   Explosion protection
   Page 10
   Electrical and non-electrical devices are identified using the same scheme.
5. Example identification of a non-electrical device:
   II 2G Ex h IIC T6 Gb X
   II 2D Ex h IIIC T80°C Db X
6. Example identification of an electrical device:
   II 2G Ex e mb IIC T6 Gb X
   II 2D Ex e mb IIIC T80°C Db X
   In addition, the ambient temperature in which it is permitted to be used (e.g. -10°C≤Ta≤+50°C) is
   also printed on the products.
   In the case of devices that have both markings, the respective lower Ex characteristic values shall be
   used.
   Product group
   Equipment category / zone
   Ex-identification
   Ignition protection
   Explosion group
   Temperature class
   Equipment
   protection level
   Special
   conditions
   Gas atmosphere
   Dust atmosphere
   The two identifications differ only in terms of
   the type of ignition.Chapter 16:
   Explosion protection
   Page 11
   Example of marking on ATEX components:Chapter 16:
   Explosion protection
   Page 12
   For correct product selection it is important to know the meaning of the
   individual elements of the ATEX marking.
7. Product group:
    Product group I encompasses devices that are intended for use in mining. Mine gas or
   combustible dust can occur here. Hafner products are not suitable for this area.
    Product group II encompasses all areas at risk of explosion, with the exception of mining.
8. Equipment category / zone:
   ATEX devices are split into three different categories per 2014/34/EU.
   o Category 1 (not covered by any Hafner devices):
   The devices guarantee a very high level of safety and are intended for use in areas
   where a potentially explosive atmosphere is continuously present, present for long
   periods of time or frequently present.
   o Category 2
   The devices guarantee a high level of safety and are intended for use in areas where
   a potentially explosive atmosphere is likely to occur occasionally. Devices from
   category 2 can also be used in category 3.
   • Category 3
   The devices offer the required level of safety in normal operation and are
   intended for use in areas where a potentially explosive atmosphere is not
   expected to occur, and where if it does occur, it is likely to do so only infrequently
   and for a short period of time.
   The classification is to be made by the system operator.Chapter 16:
   Explosion protection
   Page 13
   Overview of categories:
   Gases, vapours and mists Dusts
   Category 1
   (Not part of the Hafner
   product range)
   Category 1G
   For use in zones 0, 1 and 2
   Category 1D
   For use in zones 20, 21 and 22
   Category 2 Category 2G
   For use in zones 1 and 2
   Category 2D
   For use in zones 21 and 22
   Category 3 Category 3G
   For use in zone 2
   Category 3D
   For use in zone 22
   The zones are classified as follows:
   Gases, vapours and mists Dusts
   Zone 0
   Area in which a potentially explosive atmosphere consisting
   of a mixture of flammable substances in the form of gas,
   vapour or mist is continuously present with air or is present
   for long periods of time or frequently.
   Zone 20
   Area in which a potentially explosive atmosphere in the
   form of a cloud of combustible dust is continuously present
   with air or is present for long periods of time or frequently.
   Zone 1
   Area in which a potentially explosive atmosphere consisting
   of a mixture of flammable substances in the form of gas,
   vapour or mist is likely to occur with air in normal operation
   from time to time.
   Zone 21
   Area in which a potentially explosive atmosphere in the
   form of a cloud of combustible dust is likely to occur with
   air in normal operation from time to time.
   Zone 2
   Area in which a potentially explosive atmosphere as a
   mixture of combustible substances in the form of gas,
   vapour or mist with air is not expected to occur in normal
   operation, and if it does occur, it is likely to do so only for a
   short period of time.
   Zone 22
   Area in which a potentially explosive atmosphere in the
   form of a cloud of combustible dust in air is not likely to
   occur in normal operation, and if it does occur, it is likely to
   do so only for a short period of time.Chapter 16:
   Explosion protection
   Page 14
   Category 1
   Zone 0/20
   The following illustration shows how zones are assigned in a filling station. Accordingly, devices
   within the tanker and the underground tanks must be designed for zones 0 and 20. Devices in the
   vicinity of the fuel filling process must be designed for zones 1 and 21 and devices in the general
   surrounding area for zones 2 and 22.
   Illustration for an area in which explosive gases could occur:
   Illustration for an area in which explosive dusts could occur:
   Category 3
   Zone 2/22
   Category 2
   Zone 1/21Chapter 16:
   Explosion protection
   Page 15
   The zone is mentioned again in the rear section of the ATEX marking, but not per ATEX, but rather
   per the EN ISO 80079-36 standard. Zone distribution per EN ISO 80079-36 and 2014/34/EU is
   identical:
   EN ISO 8079-36
   EPL (Equipment protection level)
   ATEX 2014/34/EU
   Device category / zone
   Ma M1
   Mb M2
   Ga 1G
   Gb 2G
   Gc 3G
   Da 1D
   Db 2D
   Dc 3D
9. Ignition protection type:
   Technical measures must be used to ensure that no ignition source can act upon an assumed
   explosive mixture, in accordance with the classification. There are multiple technical options to
   implement explosion protection for an electrical device. An overview of the types of ignition
   protection can be found in the following tables.
   Pressure-tight encapsulation is often chosen for switchgear and transformers. For terminal boxes
   and squirrel-cage motors the measure of increased safety is often applied. Overpressure
   encapsulation is mainly used for equipment with higher power ratings (switchgear cabinets, large
   motors). Intrinsically safe circuits can only be considered for circuits with lower power ratings. This
   type of protection is used for measurement and control circuits as well as for the electrical
   connection of sensors and actuators. Here, the safety barrier is located outside the hazardous area.Chapter 16:
   Explosion protection
   Page 16
   Overview of the types of ignition protection for electrical devices:
   Standard Type of ignition protection Abbreviation
   EN 60079-6 Liquid encapsulation ob / oc
   Zone: 1, 2
   EN 60079-2 Overpressure encapsulation
   p
   Zone: 1, 2
   Zone: 21, 22
   EN 60079-5 Sand encapsulation q
   Zone: 1, 2
   EN 60079-1 Flameproof da / db / dc
   Zone: 0, 1, 2
   EN 60079-7 Increased safety eb / ec
   Zone: 1, 2
   EN 60079-11 Intrinsically safe
   ia / ib / ic
   Zone: 0, 1, 2
   Zone: 20, 21, 22
   EN 60079-18 Encapsulation
   ma / mb / mc
   Zone: 0, 1, 2
   Zone: 20, 21, 22
   EN 60079-15

• Non-sparking equipment
• Sparking equipment with
  suitable protection
• Vapour-proof housing
  nA
  nC
  nR
  Zone: 2
  EN 60079-31
  Protection by housing
  IP protection and
  temperature limitation
  ta, tb, tc
  Zone: 20, 21, 22Chapter 16:
  Explosion protection
  Page 17
  Overview of the types of ignition protection for non-electrical devices:
  Standard Type of ignition protection Abbreviation
  EN 60079-2 Overpressure encapsulation p
  EN 60079-1 Pressure-tight encapsulation d
  EN 80079-36 Basics –
  non-electrical devices –
  EN 80079-37
  Non-electrical devices
  Constructional safety c
  Liquid immersion k
  Control of ignition sources b
  h
  EN 60079-31 Protection by housing t
  Hafner valves are always labelled with an “h”, which stands for constructional safety. For this, the
  valves are considered with regard to the following possible ignition sources:

1. Hot surfaces
2. Mechanically generated sparks
3. Static electricityChapter 16:
   Explosion protection
   Page 18
4. Explosion group
   Depending on the type of protection, explosion-protected equipment for gases, mists and vapours
   is divided into three explosion groups (IIA-IIB-IIC). The explosion group is a measure of the ignition
   transmission capability of gases (explosive atmosphere). The requirements on the equipment
   increase from IIA to IIC. Classification by to gas groups:
   Gas group device Use in gas groups Example Danger of the gases
   IIA IIA Propane Low
   IIB IIA + IIB Ethylene Medium
   IIC IIA + IIB + IIC Hydrogen High
   Combustible dusts are classified into corresponding dust groups:
   Dust group Use in dust
   group
   Definition Explanation
   IIIA IIIA Combustible lint Small solid particles, including fibres with a
   nominal size greater than 0.5 mm, which may
   be suspended in the atmosphere but which
   may settle under their own weight, which may
   burn or smoulder in air and which may form
   explosive mixtures with air at atmospheric
   pressure and normal temperatures.
   IIIB IIIA + IIIB Non-conducting dusts Combustible dust with an electrical resistance
   greater than 103 Ohm/m.
   IIIC IIIA + IIIB + IIIC Conducting dusts Combustible dust with an electrical resistance
   less than or equal to 103 Ohm/m.Chapter 16:
   Explosion protection
   Page 19
5. Temperature class
   Flammable gases and vapours are divided into temperature classes in accordance with their
   flammability. The ignition temperature is the lowest temperature of a heated surface at which the
   ignition of a gas/air or vapour/air mixture occurs. In other words, it is the lowest temperature value
   at which a hot surface can ignite the corresponding explosive atmosphere.
   The maximum surface temperature of electrical equipment must always be lower than the ignition
   temperature of the gas/air or vapour/air mixture in which it is used.
   Equipment of a higher temperature class (e.g. T6) can therefore also be used for lower
   temperature classes (T1-T5).
   Temperature
   class
   Temperature range
   of the mix (°C)
   Max. surface
   temperature (°C)
   Typical gases
   T1 ≥ 450°C 450°C Methane, acetone,
   ammonia, methanol,
   propane, acetic acid,
   town gas, hydrogen
   T2 ≥ 300 – 450°C 300°C Ethylene, acetylene
   T3 ≥ 200 – 300°C 200°C Petroleum, diesel,
   heating oils, hydrogen
   sulphide
   T4 ≥ 135 – 200°C 135°C Acetaldehyde, ethyl ether
   T5 ≥ 100 – 135°C 100°C
   T6 ≥ 85 – 100°C 85°C Carbon disulphide
   It is not possible to give generally applicable values for dust-specific characteristic values. The
   following table contains some limit values for corresponding products.
   Substance T.ign. (°C) T.smol. (°C)
   Wood ≥ 410 ≥ 200
   Brown coal ≥ 380 ≥ 250
   Hard coal ≥ 500 ≥ 240
   PVC ≥ 530 ≥ 340
   Aluminium ≥ 560 ≥ 270
   Sulphur ≥ 240 ≥ 250
   Lycopodium ≥ 410 -Chapter 16:
   Explosion protection
   Page 20
   T.ign. (ignition temperature):
   Lowest temperature of a hot inner wall (e.g. oven) at which the dust/air mixture ignites upon brief
   contact. The surface temperature must not exceed 2/3 of the ignition temperature in °C of the
   respective dust/air mixture, e.g.
   Starch / milk powder / gelatine: Ignition temperature 390°C x 2/3
   = 260°C max. permissible surface temperature
   T.smol. (smouldering temperature):
   The lowest temperature of a hot surface at which a layer of dust of a specified thickness (5 mm) can
   ignite. On surfaces where a dangerous deposit of smouldering dust cannot be effectively prevented,
   the surface temperature must not exceed the smouldering temperature of the respective dust, less
   75K. For layer thicknesses >5 mm, a further reduction of the surface temperature is required, e.g.
   Grinding dust: Smouldering temperature 290°C – 75°C
   = 215 °C max. permissible surface temperature
   The smouldering temperature is usually well below the ignition temperature determined for a dust
   cloud. The smouldering temperature decreases almost linearly with the increase in layer thickness.
   Safety distances must be observed for the permissible surface temperatures.
   In summary, the following criteria must be taken into account for explosive
   dusts, gases, mists and vapours:
   Dusts Gases, vapours and mists
    Smouldering temperature
    Ignition temperature
    Dust group IIIA, IIIB, IIIC
    Flashpoint
    Ignition temperature
    Lower/upper explosion limit
   (concentration)
    Ignition energy (gas group IIA, IIB, IIC)Chapter 16:
   Explosion protection
   Page 21
   Hafner offers a large selection of explosion-protected valves with different
   types of ignition protection.
   Overview table 1:
   Type of ignition protection h
   (non-electrical)
   Ex nA Ex ia Ex m
   Constructional safety Non-sparking Intrinsically safe Encapsulation
   Certificates ATEX
   IECEx
   CSA / FM
   Zone 1G
   2G
   21D
   22D
   Temperature class T6 T5 / T6 T6 T4
   Explosion group Not applicable IIC / IIIC IIC / IIIC IIC / IIIC
   Max. possible temperature
   range
   -50°C to +50°C -15°C to +50°C -40°C to +50°C -20°C to +50°C
   Stainless steel version
   Electrical connection – T6: Plug for 4-8 mm cable

• T5: Plug for 6-8 mm cable
  Plug for 6-8 mm cable 3 metre moulded cable,
  10 metres on request
  Power consumption – T6: 2 Watts
• T5: 3 Watts
  1.6 Watts 5.0 Watts
  IP protection class IP 65 IP 65 IP 65Chapter 16:
  Explosion protection
  Page 22
  Overview table 2:
  Type of ignition
  protection
  e mb Ex dm Ex d Ex m CSA/FM
  Increased safety /
  encapsulation
  Encapsulation /
  flameproof
  Flameproof Encapsulation
  Certificates ATEX
  IECEx
  CSA / FM
  Zone 1G
  2G
  21D
  22D
  Temperature class T6 T5 T4 (AC) / T6 (DC) T4
  Explosion group IIC / IIIC IIC / IIIC IIC / IIIC
  Max. possible
  temperature range
  -40°C to +50°C -50°C to +50°C -50°C to +40°C -20°C to +60°C
  Stainless steel design
  Electrical connection
  M20x1,5
  6 – 13 mm
  M20x1,5
  6 – 8 mm
  M20x1,5
  Cable gland not included
  30 cm strands
  Power consumption 4.8 Watts 3.0 Watts 3.0 Watts 4.6 Watts
  IP protection class IP 65 (IP 67 optional) IP 65 IP 66 IP 65Chapter 16:
  Explosion protection
  Page 23
  The following tree may assist in product selection.
  The following product selection tree can help to determine the correct type of ignition protection.
  However, only ATEX products are considered here. Some of these are also certified per IECEx. See
  table on pages 21 and 22 for this.Chapter 16:
  Explosion protection
  Page 24
  Explosion-proof valves from Hafner are also available with a SIL3
  certificate.
  Functional safety is becoming increasingly important in safety-relevant applications.
  To meet this requirement, many of the Hafner valves are available with a SIL 3 certificate.
  The valves are certified per IEC 61508:2010 (1-7) by the Swiss certification
  company exida.
  Compressed air hoses must be antistatic.
  In explosion-proof environments it is important that the hoses used are antistatic. It is FORBIDDEN
  to use an electrostatic hose. In everyday life we usually perceive electrostatic charges when they are
  discharged. For example, when we reach for a door handle and feel a small sting on our hand.
  Static charges can be very annoying during the production and processing of plastics. The charged
  particles can adhere to each other, attract and hold dust from the environment, making lamination
  or printing difficult.
  • These antistatic hoses are available with the following diameters:
  o 4/2.5 black
  o 6/4 black
  o 8/6 black
  o 10/8 black
  o 12/10 black
  • Pressure rating: 5 to 25 bar (depending on diameter, at 20°C)
  • Temperature range: -30°C to +80°C
  ATEX II 2 G/DChapter 16:
  Explosion protection
  Page 25
  Screw fittings are not covered by the ATEX directive.
  Pneumatic screw fittings are not electrical devices,
  therefore metal (copper) and stainless steel versions can
  be used in ATEX environments.
  Air treatment units are generally not covered by the ATEX directive.
  Most of our maintenance units are not covered by the ATEX directive, as they do not have their own
  potential ignition sources or internal explosive atmosphere. The following units are available:
  o Filter
  o Filter controller
  o 2-part, 3-part units
  o Pressure regulator
  o Switch-on valve, start-up valve
  o Accessories, containers, manometers, fastening elements
  Electrically actuated maintenance units are not included. ATEX-approved units must be used for
  this.
  All information in this training document is provided without guarantee. The system operator is
  responsible for selecting the correct devices in hazardous areas.

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