General conditions for pneumatic circuits
- it is necessary to observe appropriate safety rules, instructions, recommendation and specifi ed parameters (temperature, pressure etc.), during setting in operation
- areas, which are pressurized even after closing of main air supply, should be specially marked in pneumatic circuits
- it is necessary to make allowance to product failure, eventually danger situations due to wrong operation, age or failure
- we reccomend to mark with special sign whole pneumatic circuits, where the high caution during service is necessary
- we do not reccomend to weld by electric arc on machinery, where pneumatic cylinders are mounted
- end users must take sufficient preventive steps to prevent injuries on material and health of employees
Distribution of compressed air
The operational reliability and service life of a pneumatic system depend to a large extent on the preparation of the compressed air. Impurities in the compressed air such as scale, rust and dust as well as the liquid constituents in the air which deposit as condensate can cause a great deal of damage in pneumatic systems. These contaminants accelerate wear on sliding surfaces and sealing elements, adversely aff ecting the functioning and service life of pneumatic components. As a result of switching the compressors on and off , pressure fluctuations occur which have an unfavourable effect on the functioning of the system. In order to eliminate these effects, compressed air service units must be installed in every pneumatic control system.
Example of air distribution
Compressed air goes from compressor through coarse fi lter to air receiver. then the air is led into air dryer and another filter, which should catch junk, released from air receiver and dryer. Air drier is used only in substantiated cases. Then distribution in plastic or metal tubes follows, whereas the tubes should incline 1-2° due to appropriate condensed water drain. Particular distributaries to consuming devices should go out from main distribution towards to crossways up. If there are intense pressure beats during compressed air consumption, it is usefull to use another smaller air receiver between distributary and consuming device. This another receiver should balance the pressure beats. Finally, the standard FRL unit is piped, or some of air preparation modules..
 |
Legend: 1) compressor 2) coarse filter 3) air reciever 4) drain cock 5) dryer 6) filter 7) shut off valve 8) standard FRL unit |
Modified compressed air
Modified compressed air = filtered air without solid particles and liquids, eventually lubricated.
All our produced pneumatic items are greased with special grease, so it isn‘t necessary to lubricate air in standard conditions. But we recommend to regurarly check lifetime grease level and if decline will occur, renew grease filling. However these items couldn‘t be exposed to air polluted by water or oil, because the lifetime grease should flush out. Since this, the air should be lubricated, or lifetime grease filling should be renewed. Special grease for lifetime filling is available, please see chapter Air preparation or contact our sales dept.
If pneumatic circuit is stressed and heavy duty, we recommend to lubricate air due to increase lifetime of pneumatic items.
The operational reliability and service life of pneumatic systems depend among others to quality of incoming compressed air.
Junk and moisture contained in air increases surface wear of parts and gaskets, what brings decline of economy and lifetime of pneumatic items. So, air preparation consist of liquid removal (mainly water and oil), suitable dimensioned filtration of solid junk and appropriate air lubricator.
Air after modification must be so clean to not cause any damage on pneumatic system and sequentially damage to machinery. Using of filter the maximal flow capacity is lower because filter is basically resistance, which intercepts air flow. Filter should be with such a filter element, so the sufficient quality will be reached with reference to economy of system. If high quality of compressed air is required, the air should be filtered in several steps. If we use only coalescing filter, which will ensure requested air quality, we have to calculate with serious decrease its lifetime.
The compressed air quality is expressed by quality classes, which are described in ISO 8573-1 standard. Acceptable values of junk are listed in this standard too.
| Class | Solid junk | Max. pressure dew point [°C] |
Max. oil concentration [mg/m3] |
|
| Max. particle size[µm] |
Max. concentracion [mg/m3] |
|||
| 1 | 0,1 | 0,1 | -70 | 0,01 |
| 2 | 1 | 1 | -40 | 0,1 |
| 3 | 5 | 5 | -20 | 1 |
| 4 | 15 | 8 | +3 | 5 |
| 5 | 40 | 10 | +7 | 25 |
| 6 | — | — | +10 | — |
| 7 | — | — | unstipulated | — |
| Area | Solid junk | Water | Oil | |||
| Max.class | Max. particle size [µm] |
Max. class | Max. dew point [°C] |
Max. class | Max. concentration [mg/m3] |
|
| Pneumatic cylinders | 5 | 40 | 4 | +3 | 5 | 25 |
| Pneumatic vylves | 3 to 5 | 5 to 40 | 4 | +3 | 5 | 25 |
| Fine regulators | 3 | 5 | 4 | +3 | 3 | 1 |
| Measurements | 2 | 1 | 4 | +3 | 3 | 1 |
| Other industry | 5 | 40 | 3 to 7 | -20 to +10 and more | 3 to 5 | 1 to 25 |
Mounting, operation and service of air preparation units
There is necessary to pay attention to flow direction, which is marked by arrows or marks IN/OUT during mounting of units. The following sequence of units sort should be observed: shut off valve, particulate filter, coalescing filter regulator, lubricator. Bowls of particulate units must be mounted towards to bottom. Lubricator should be as closed as possible to consuming device (max. 5 to 10m).
Condensate water level in bowl mustn‘t exceed level of bottom of filter element or mark on a bowl. For drain, there is connection for tube on the bottom of bowl. Automatic drain doesn‘t practically need service, but if semi-automatic drain is used, it is necessary to regularly check level of condensed water in bowl and expel it always if level of water achieve filter element or mar on the bowl. Semi-automatic drain automatically expels water if the primary pressure drop under 0,05 MPa. If it is necessary to expel water immediately, there are 2 systems: one has got button - pressing the button the water is removed. The second system is without button - for removing the water simply push the tube connection towards to the bowl. If the filter element is polluted, it must be changed. Before disassembling shut off air supply and depressurize the filter, remove bowl (release safety lock on side of bowl or push the bowl towards to the unit, turn it off 45° and pull it out). Then unscrew the baffle and remove filter element. Procedure at assembling is the same, but in reverse order.
If lubricator is used, it is necessary to keep sufficient level of oil. Oil refilling is possible when air supply is shut off directly into bowl, or by button head fill nut. Before disassembling shut off air supply and depressurize the lubricator, remove bowl (release safety lock on side of bowl or push the bowl towards to the unit, turn it off 45° and pull it out). Fill in bowl (see level mark on the bowl) and mount bowl back. Procedure at assembling is the same, but in reverse order. It is necessary to use only recommended oils.
Some bowls are made from polycarbonate and could be cleaned only with household soap and water. Do not use any solvent (alcohol), bowls may crackle
Recommended oils for compressed air lubricating
Primarily we recommend to use our pneumatic oil with order code 2995 0101 0000 0000, which composition was specially designed for this purpose. It is oil, which is foamless, nonaggressive to gaskets and has suitable mechanical characteristics (viscosity etc.).
| Supplier: | Designation: | Supplier: | Designation: | |
| Stransky a Petrzik | Pneumatic oil, order code: 2995 0101 0000 0000 |
Fuchs | Renolin MR1, MR3 | |
| Shell | Tellus Ol 10 | Optimol | Ultra 10 | |
| Mobil Oil | Velocite Oil No. 6 | Agip | OSO 10 | |
| BP | Energol HLP10 | Elf | Spinelf 5, 10 | |
| Esso | Spinesso 10, Nutto H5, H10 | Total | Azolla 10 | |
| Aral | Vitamol GF10, DE10 Sumorol CM5, CM10 |
Fina | Cirkan 10 |