Pneumatic control valve action is what reason is caused?

Pneumatic control valve action is what reason is caused? Pneumatic control valve action. No signal, no gas source (1) gas source, (2) due to the air source water freezes in winter, cause the clogging in duct blockage or filter, pressure reducing valve failure, (3) compressor fault; (4) air duct leakage. Air supply, no signal. 1) regulator malfunction, (2) pipe leak signal; (3) locator corrugated pipe leakage; (4) adjust the retinal damage. The locator without air. (1) filter clogging; (2) reducing valve fault; (3) pipe leakage or jam. Locator has a gas source, no output. Locator orifice clogging. There are signals, no action. (1) the valve core loss, or (2) the valve core and valve seat's death; (3) stem bend or break; (4) seat valve core to freeze or focal piece of dirt; (5) spring actuator due to long-term need not rust. The choice of the form of the choice of pneumatic - valve structure: steam flow control should choose single seat; Large diameter, large flow, low pressure difference occasions should choose butterfly valve, but at the moment, leakage is larger; When the medium to high pressure, should choose high pressure pneumatic control valve; To facilitate drainage, prevent the valve plug, optional Angle of pneumatic control valve; Heat exchanger of the water or water temperature regulation optional tee pneumatic control valve. Pneumatic control valve caliber choice: using on-off pneumatic control valve, can choose the valve diameter pipe diameter according to receive directly; Other situations should be according to the maximum flow of medium and valve pressure drop calculation of flow capacity Kv value to determine the diameter of the valve.