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Common faults of SIPART PS2 positioner include gas circuit problems, electrical problems, mechanical problems and other problems. The following are some common faults and corresponding solutions:
Gas circuit leakage
Fault phenomenon: The valve moves slowly, oscillates, drifts, cannot be completely closed or opened, the positioner displays error code 1, etc., and may also be accompanied by a “puff puff” sound.
Possible causes: Leakage occurs in the gas circuit at the rear of the positioner, the grinding head position of the actuator, the air pipe joint between the air source output to the cylinder, the cylinder body or the diaphragm.
Solution: Use soapy water to detect the outlet gas circuit of the positioner and the grinding head position of the actuator, find the leakage point and seal it; check whether the air pipe joint, cylinder body or diaphragm and other components are well sealed, and replace them if damaged.
Fault phenomenon: The valve moves slowly, cannot reach the set position or does not move.
Possible causes: The air source pressure is too low, too high or unstable.
Solution: Check whether the air source pressure is within the working pressure range of the positioner and adjust the air source pressure to the appropriate value; if the air source pressure is unstable, check whether there is any fault in the air source system, such as compressor failure, filter blockage, etc., and perform corresponding repairs or replacements.
Pneumatic actuator failure
Failure phenomenon: The valve moves slowly, does not move, oscillates or positions inaccurately.
Possible causes: The piston, sealing ring, spring and other components inside the pneumatic actuator are damaged, resulting in poor air flow or weak actuator; the actuator is poorly lubricated, resulting in increased friction.
Solution: Repair or replace damaged components inside the pneumatic actuator; lubricate the actuator to ensure its flexible movement.
Piezoelectric valve failure
Failure phenomenon: The CPU test on the display screen flashes once every 2 seconds.
Possible causes: The piezoelectric valve does not switch, usually because wet compressed air produces water in the valve branch pipe, causing the piezoelectric valve to be blocked or damaged.
Solution: Dispose of the water in the valve branch pipe in time, and use dry air to calibrate in steps. If necessary, calibrate in a 50-70℃ temperature cabinet; if the piezoelectric valve is damaged, the piezoelectric valve needs to be replaced.
Sensor failure
Failure phenomenon: The positioner cannot accurately detect the position of the valve, resulting in inaccurate valve positioning or oscillation.
Possible causes: The sensor is damaged, the connection between the sensor and the actuator is loose, or the sensor is installed in an incorrect position.
Solution: Check whether the sensor is damaged, and replace it if damaged; check whether the connection between the sensor and the actuator is loose, and tighten it if loose; adjust the installation position of the sensor to ensure that it can accurately detect the position of the valve.
Circuit board failure
Failure phenomenon: Various abnormal phenomena occur in the positioner, such as no action, unstable action, display of error code, etc.
Possible causes: Damaged components on the circuit board, damp or corroded circuit board, loose soldering points on the circuit board, etc.
Solution: Check if the components on the circuit board are damaged, and replace them if damaged; dry and clean damp or corroded circuit boards; check if the soldering points on the circuit board are loose, and re-solder them if loose.
Actuator stuck
Fault phenomenon: The valve moves slowly, does not move, or is stuck at a certain position.
Possible causes: The internal parts of the actuator are worn, deformed, or impurities enter, causing the actuator to be stuck; the installation position of the actuator is incorrect, resulting in increased friction between the valve and the pipeline.
Solution: Disassemble and clean the actuator to remove impurities and worn parts; replace worn or deformed parts; adjust the installation position of the actuator to ensure that the friction between the valve and the pipeline is minimized.
Feedback rod is loose or damaged
Fault phenomenon: The positioner cannot accurately control the position of the valve, causing the valve to oscillate or inaccurately position.
Possible causes: The connection between the feedback rod and the actuator is loose or the feedback rod itself is damaged.
Solution: Check whether the connection between the feedback rod and the actuator is loose, if so, tighten it; check whether the feedback rod is damaged, if so, replace it.
Valve failure
Failure phenomenon: The valve cannot be completely closed or opened, the valve leaks, the valve movement is unstable, etc.
Possible causes: The valve seal is damaged, the valve core is worn or deformed, the valve transmission mechanism fails, etc.
Solution: Repair or replace the valve seal, valve core or transmission mechanism.
Parameter setting error
Failure phenomenon: The positioner cannot work normally or works unstably, such as slow valve movement, oscillation, overshoot, etc.
Possible causes: When setting the parameters of the positioner, the user sets the wrong value or parameter combination.
Solution: Check whether the positioner’s parameter settings are correct. If there are any errors, modify them. If you are not sure about the correct setting of the parameters, you can refer to the positioner’s manual or consult the manufacturer’s technical support staff.
Communication failure
Failure phenomenon: The positioner cannot communicate with the control system, resulting in the inability to remotely control the valve.
Possible causes: Poor communication line connection, incorrect communication protocol setting, control system failure, etc.
Solution: Check whether the communication line is well connected. If it is loose or damaged, repair it; check whether the communication protocol setting is correct to ensure that it is consistent with the control system setting; if the control system fails, you need to contact relevant technicians for repair.
Environmental factors
Failure phenomenon: The positioner works unstably or fails under harsh environmental conditions, such as high temperature, low temperature, humidity, vibration, etc.
Possible causes: Environmental temperature, humidity, vibration and other factors exceed the working range of the positioner, resulting in the performance degradation or failure of the positioner.
Solution: Take appropriate protective measures, such as installing a radiator, heater, moisture-proof box, shock absorber, etc. to improve the working environment of the positioner; if the environmental conditions cannot be changed, consider replacing the positioner with one that is suitable for the environmental conditions.