What is the cause of the non-action of the regulating valve?

What is the cause of the non-action of the regulating valve?

The regulating valve does not work. The symptoms and causes are as follows:

1. No signal, no gas source 1 gas source is not open, 2 due to air source water icing in winter, causing air duct blockage or filter, pressure relief valve blockage failure, 3 compressor failure; 4 gas source manifold leakage.

2. There is a gas source and no signal. 1 regulator failure, 2 signal tube leakage; 3 positioner bellows leakage; 4 regulation mesh diaphragm damage.

3. The positioner has no air supply. 1 filter blocked; 2 pressure relief valve failure; 3 pipeline leakage or blockage.

4. The positioner has a gas source and no output. The orifice of the positioner is blocked.

5. There is signal, no action. 1 spool is detached, 2 spools are stuck with the valve seat; 3 stem is bent or broken; 4 valve seat spool is frozen or coke block dirt; 5 actuator spring is rusted due to long-term use.

Control valve selection

Selection of structural form: steam flow control should select single valve seat; large diameter, large flow, low pressure difference should choose butterfly valve, but the leakage is large at this time; when the medium is high pressure, high pressure regulating valve should be selected; Sewage, prevent valve blockage, optional angle control valve; optional three-way control valve for water volume or water temperature adjustment of heat exchanger.

Selection of regulating valve diameter: When using double-position regulating valve, the valve diameter can be directly selected according to the pipe diameter; in other cases, the valve capacity should be determined according to the maximum flow rate of the medium and the valve pressure drop to calculate the flow capacity Kv value.