Process Engineering Division – Instrumentation and Automation Section – Daily Question – Question dated 2020-08-30
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Process Engineering Division – Instrumentation and Automation Section – Daily Question – Question from 2020-08-30: Discussion question: 220. What are the common reasons why a control valve does not function?
1. Instrumentation system failure, such as: ① Control valve with solenoid valve, loss of power to the solenoid valve； ②Faulty valve positioner or electrical converter ； ③No electrical signal to the valve positioner ； ④No gas supply ； 2. Mechanical failures: ① Sticking in the mechanical components, with severe sticking; in many pneumatic butterfly valves that operate outdoors for long periods of time, the shaft sleeves rust ； ②Actuator with cylinder; air leakage in the cylinder section and damaged piston rings ；
1. Instrumentation system failure, such as: ① Control valve with solenoid valve, loss of power to the solenoid valve； ②Faulty valve positioner or electrical converter ； ③No electrical signal to the valve positioner ； ④No gas supply ； 2. Mechanical failures: ① Sticking in the mechanical components, with severe sticking; in many pneumatic butterfly valves that operate outdoors for long periods of time, the shaft sleeves rust ； ②Actuator with a cylinder; air leakage in the cylinder section and damaged piston rings.
1. Instrument system failure, such as: ? ?① Control valve with solenoid valve, the solenoid valve loses power； ? ?② Fault in the valve positioner or electrical converter ； ? ?③No electrical signal to the valve positioner ； ④No gas supply ； 2. Mechanical failures: ? ?① There is jamming in the mechanical components, and the jamming is severe; in many pneumatic butterfly valves that operate outdoors for long periods of time, the shaft sleeves rust ； ? ?② Actuator with cylinder; air leakage in the cylinder section and damaged piston rings ；
1. Instrument system failure, such as: ? ?① Control valve with solenoid valve, the solenoid valve loses power； ? ?② Fault in the valve positioner or electrical converter ； ? ?③No electrical signal to the valve positioner ； ④No gas supply ； 2. Mechanical failures: ? ?① There is jamming in the mechanical components, and the jamming is severe; in many pneumatic butterfly valves that operate outdoors for long periods of time, the shaft sleeves rust ； ? ?② Actuator with cylinder; air leakage in the cylinder section and damaged piston rings ；
The drive side loses air supply and power supply; the actuator gets stuck or is damaged; the valve body gets stuck
1. Instrument system failure, such as: ? ?① Control valve with solenoid valve, the solenoid valve loses power； ? ?② Fault in the valve positioner or electrical converter ； ? ?③No electrical signal to the valve positioner ； ④No gas supply ； 2. Mechanical failures: ? ?① There is jamming in the mechanical components, and the jamming is severe; in many pneumatic butterfly valves that operate outdoors for long periods of time, the shaft sleeves rust ； ? ?② Actuator with a cylinder; air leakage in the cylinder section and damaged piston rings.
1. Instrument system failure, such as: ? ?① Control valve with solenoid valve, the solenoid valve loses power； ? ?② Fault in the valve positioner or electrical converter ； ? ?③No electrical signal to the valve positioner ； ④No gas supply ； 2. Mechanical failures: ? ?① There is jamming in the mechanical components, and the jamming is severe; in many pneumatic butterfly valves that operate outdoors for long periods of time, the shaft sleeves rust ； ? ?② Actuator with cylinder; air leakage in the cylinder section and damaged piston rings ；
1. No signal, no air supply. 1) The gas supply is not turned on, 2) Ice forms in the gas supply due to moisture, causing blockages in the air ducts or failures of the filters and pressure regulators, 3) Compressor failure, 4) Leakage in the main gas supply pipe. 2. There is air supply, but no signal. 1) Regulator failure. 2) Air leakage in the corrugated steel of the locator. 3) Damage to the diaphragm of the regulating element. 3. No air supply to the locator: 1) Clogged filter, 2) Failure of the pressure reducing valve, 3) Leaks or blockages in the pipes. 4. Air supply is available to the locator, but no output. The throttle orifice of the locator is blocked. 5. There is a signal, but no action is taken. 1) The valve core has fallen off, 2) The valve core is stuck to the body or to the valve seat, 3) The valve stem is bent or broken, 4) The valve seat and valve core are covered with ice, deposits, or dirt. 5) The actuator spring has rusted due to long-term disuse.
1. Instrument system failure, such as: ? ?① Control valve with solenoid valve, the solenoid valve loses power； ? ?② Fault in the valve positioner or electrical converter ； ? ?③No electrical signal to the valve positioner ； ④No gas supply ； 2. Mechanical failures: ? ?① There is jamming in the mechanical components, and the jamming is severe; in many pneumatic butterfly valves that operate outdoors for long periods of time, the shaft sleeves rust ； ? ?② Actuator with cylinder; air leakage in the cylinder section and damaged piston rings ；
No air supply, locator failure, membrane head or cylinder failure, solenoid valve damage, shaft sleeve jammed, valve core jammed, control signal not delivered to the valve, interlock not reset, amplifier failure, pressure relief valve damaged