Maintenance and Fault Analysis of Pneumatic Regulating Valve
Published：2016-07-25 Views：1622 times
Pneumatic control valve performance will directly affect the quality of the entire system. As the pneumatic control valve in the field with the media is in direct contact with the work environment is very bad, so prone to various failures. In the production process, in addition to at any time to exclude these failures, but also must be regular maintenance and regular maintenance. Especially for the use of particularly harsh environment control valve, should pay more attention to maintenance and regular maintenance.
So the pneumatic control valve in the installation and use should pay attention to the following aspects:
1. Daily maintenance of pneumatic control valve:
When the control valve with graphite - asbestos as a filler, about three months should be added to the filler on a lubricant to ensure that the valve flexible and easy to use. If the packing pressure cap is found to be very low, it should be filled with filler. If the PTFE packing is found to be hardened, it should be replaced in time. The operation of the regulating valve should be taken into account in the tour inspection, check the valve position indicator and the regulator output Whether the anastomosis; on the positioner of the control valve to always check the gas source, find the problem in a timely manner; should always keep the health of the control valve and the components are easy to use.
2. Common faults and causes:
(1) The control valve does not operate. Symptoms and causes are as follows:
A. No signal, no gas source: ① gas is not open ② due to the source of water in the winter icing, resulting in duct clogging or filter, pressure relief valve failure. ③ compressor failure. ④ gas mains leakage.
B. There is gas, no signal: ① regulator failure. ② signal tube leakage. ③ positioner bellows leak. ④ adjust the damage to the membrane.
C. Locator No air supply: ① filter blockage. ② failure valve failure. ③ Pipeline leaks or clogging.
D. The positioner has air supply, no output: the orifice of the positioner is blocked.
E. Signal, no action: ① spool off, ② spool and seat stuck. ③ Stem bent or broken. ④ valve seat spool freeze or coke dirt. ⑤ executive spring because of long-term and rust.
(2) the operation of the control valve instability, failure and the reasons are as follows:
A. Air pressure is unstable: ① compressor capacity is too small. ② failure valve failure.
B. Signal pressure is unstable: ① The time constant of the control system is not appropriate. ② regulator output is unstable.
C. The air supply pressure is stable and the signal pressure is also stable, but the action of the control valve is still unstable: ① The ball valve of the amplifier in the locator is not badly exposed to dirt, and the output fluctuates when the air consumption is increased. ② The nozzle of the amplifier in the locator is not parallel, and the baffle can not hold the nozzle. ③ output pipe, line leakage. ④ actuator rigidity is too small. ⑤ Stem resistance in the movement of large, and the phase contact with the phenomenon of block.
So the pneumatic control valve in the installation and use should pay attention to the following aspects:
1. Daily maintenance of pneumatic control valve:
When the control valve with graphite - asbestos as a filler, about three months should be added to the filler on a lubricant to ensure that the valve flexible and easy to use. If the packing pressure cap is found to be very low, it should be filled with filler. If the PTFE packing is found to be hardened, it should be replaced in time. The operation of the regulating valve should be taken into account in the tour inspection, check the valve position indicator and the regulator output Whether the anastomosis; on the positioner of the control valve to always check the gas source, find the problem in a timely manner; should always keep the health of the control valve and the components are easy to use.
2. Common faults and causes:
(1) The control valve does not operate. Symptoms and causes are as follows:
A. No signal, no gas source: ① gas is not open ② due to the source of water in the winter icing, resulting in duct clogging or filter, pressure relief valve failure. ③ compressor failure. ④ gas mains leakage.
B. There is gas, no signal: ① regulator failure. ② signal tube leakage. ③ positioner bellows leak. ④ adjust the damage to the membrane.
C. Locator No air supply: ① filter blockage. ② failure valve failure. ③ Pipeline leaks or clogging.
D. The positioner has air supply, no output: the orifice of the positioner is blocked.
E. Signal, no action: ① spool off, ② spool and seat stuck. ③ Stem bent or broken. ④ valve seat spool freeze or coke dirt. ⑤ executive spring because of long-term and rust.
(2) the operation of the control valve instability, failure and the reasons are as follows:
A. Air pressure is unstable: ① compressor capacity is too small. ② failure valve failure.
B. Signal pressure is unstable: ① The time constant of the control system is not appropriate. ② regulator output is unstable.
C. The air supply pressure is stable and the signal pressure is also stable, but the action of the control valve is still unstable: ① The ball valve of the amplifier in the locator is not badly exposed to dirt, and the output fluctuates when the air consumption is increased. ② The nozzle of the amplifier in the locator is not parallel, and the baffle can not hold the nozzle. ③ output pipe, line leakage. ④ actuator rigidity is too small. ⑤ Stem resistance in the movement of large, and the phase contact with the phenomenon of block.