Pneumatic control valve performance will work quality directly affect the control system of the . As the pneumatic control valve in the field is in direct contact with the medium being transferred , the working environment is very bad , so prone to failure . In the production process, in addition to rule out any of these faults, but also the need for regular maintenance and periodic maintenance . Especially the regulating valve on the use of the environment particularly bad , more attention should be paid to maintenance and periodic maintenance .

Therefore, the pneumatic control valve in the installation should pay attention to the following aspects :

Maintenance of pneumatic control valve :

When the control valve with graphite asbestos packing, should be about three months to add a lubricating oil in the packing , to ensure that the valve and flexible to use . Found filling pressure cap is very low , should be added fillers , such as found in PTFE packing sclerosis , should be replaced; should pay attention to running the tour check valve , check valve position indicator and the regulator output is consistent; on the control valve with positioner should always check the gas source , identify problems timely ; keep adjusting valve part of the health and integrity of the easy to use .

Common faults and causes :

Regulating valve does not work . The following fault phenomenon and reason :

No signal , no source : source . As the gas source water freezing in the winter , leading to duct blockage or filter , valve plug failure . Compressor failure . The air duct leakage .

A gas source, no signal: regulator failure . Signal pipe leakage . The corrugated pipe leak locator . Regulate retinal chip damage .

Air-free locator: filter clogging . The relief valve failure . Pipeline leak or blockage .

A gas source locator , no output : locator orifice plug .

E. signal , no movement: ① spool off , the stuck valve and valve seat . Stem bent or broken . Spool seat block frozen or coke dirt . Actuator spring for a long time without rust .

( 2 ) valve action is not stable , the following fault phenomenon and reason :

A. air pressure instability : compressor capacity is too small . The relief valve failure .

B. signal pressure instability : time constant control system ( T=RC ) is not appropriate . The regulator output instability .

C. air pressure stability , the signal pressure is stable , but still not stable valve action : locator amplifier valve wear off by the dirt is not strict , increase gas consumption in particular will produce output shocks . Locator amplifier nozzle plate is not parallel , the baffle can't cover the nozzle . Output pipe , line leak . Actuator stiffness is too small . The friction movement of the stem , a block in contact with the phenomenon .