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 .