What are the common faults of regulating valve?

Air source system failure

1. Instrument air line blocked

Because the ball valve has throttling effect at the end of the instrument branch air line, the dirt in the air line is easy to accumulate and block here. As a result, the air pressure of the instrument is too low, the regulating valve cannot be fully opened and closed, or even the regulating valve does not act.

2. Air filter pressure reducing valve failure

The air filter pressure reducing valve uses too much dirt for a long time, the pressure reducing valve leaks air, and the set output pressure of the pressure reducing valve is too low, so that the output instrument air pressure is less than the specified pressure. As a result, the regulating valve acts slowly and cannot be fully opened or closed or even fails to act.

3. Copper pipe connection failure

The aging and air leakage of the copper pipe, the loose connection of the joint or the blockage of the copper pipe by the stolen goods cause the low signal air pressure of the instrument to cause the regulating valve not to operate and cannot be fully opened and fully closed, and the valve position in the manual state is not stable, resulting in the regulation oscillation.

4. Instrument air system failure

The air pressure station is abnormal, the purification air tank of the device is abnormal, the water cut is not timely to make the air line ice, the instrument air line leaks air or is blocked by stolen goods, resulting in the instrument air pressure of the device is too low or even no wind.

5. The valve of instrument air branch is not opened, resulting in the failure of regulating valve

This phenomenon often occurs during the period of overhaul and start-up after revamping.

Power system failure

1. The terminal of the power line is loose, short circuited, falling off, and the polarity is connected reversely

Due to field vibration, loose wiring or too much dust caused by loose wiring or poor contact, the signal from the control room to the site is sometimes absent, resulting in chaotic operation of the control valve and regulation oscillation.

Due to the wrong wiring, water or moisture in the equipment and other reasons, the power line wiring is short circuited, so that the signal received by the regulating valve is lower than the signal received by the regulator, resulting in that the regulating valve cannot be fully opened and fully closed.

2. The middle connector of the power cord or the middle injury is faulty

Due to the vibration of the environment and the pull of external forces, the failure of the insulating tape, the degradation of the insulation performance and the high temperature baking of the water in the connector, the connector of the power line is loose or seems to be broken, the short circuit between the power lines or to the ground, the connector or the power line is broken. As a result, the action of the regulating valve is not continuous, and it cannot be fully opened and closed, and it does not act. In the process of maintenance, the middle connector of the power line is connected reversely, resulting in the failure of the regulating valve.

3. The regulating valve is not controlled by the regulator

During the overhaul and start-up of the unit, the control valve is not controlled by the regulator due to the wrong connection of the power line or the wrong configuration in the control room.