Introduction to pneumatic gate valves

Pneumatic gate valve is to use compressed air as the power source, cylinder as the actuator, and with the help of electrical valve positioner, converter, solenoid valve, retention valve and other accessories to drive the valve, pneumatic gate valve to achieve switching or proportional adjustment, receive the control signal of the industrial automation control system to complete the adjustment of pipeline medium flow, pressure, temperature and other process parameters. The pneumatic gate valve is characterized by simple control, fast response, and intrinsically safe, without the need to take additional explosion-proof measures.

Pneumatic gate valve action is divided into two types of air-opening and air-closing type. Air open type is when the air pressure on the diaphragm head increases, the pneumatic gate valve to increase the direction of opening action, when the input air pressure reaches the upper limit, the valve is in a fully open state. In turn, when the air pressure decreases, the valve moves in the direction of closure, and when there is no input air, the valve is fully closed. Therefore, sometimes the air-opening type valve is also known as the fault-closing type. The direction of action of the air-closing type is exactly the opposite of the air-opening type. When the air pressure increases, the pneumatic gate valve to close the direction of action; air pressure is reduced or not, the valve to open the direction or fully open until. Therefore, sometimes also known as the fault open type. Pneumatic control valve air open or air closed, usually through the positive and negative action of the actuator and the valve state structure of the different assembly methods to achieve.

The choice of air open and air closed is based on the safety perspective of process production to consider. When the gas source cut off, the pneumatic gate valve is in the closed position safe or open position safe? For example, a heating furnace combustion control, regulating valve installed in the fuel gas pipeline, according to the temperature of the furnace chamber or the temperature of the heated material at the outlet of the furnace to control the fuel supply. In this case, it is advisable to use an open gas valve to be safer, because once the gas supply is stopped, it is more appropriate to have the valve in closed position than to have it in fully open position. If the gas supply is interrupted, the fuel valve is fully open, which will make the heating overload occurs dangerously. Another example is a heat exchanger equipment with cooling water cooling, hot materials in the heat exchanger and cooling water heat exchange is cooled, the regulating valve is installed in the cooling water pipe, with the heat exchanger material temperature to control the cooling water, in the air source interruption, the pneumatic gate valve should be in the open position more secure, it is appropriate to choose the gas off type (i.e. FO) regulating valve.