中文版The pneumatic gate valve uses the compressed air as the power source, the cylinder as the actuator, and the electrical valve positioner, converter, solenoid valve, retaining valve and other accessories to drive the valve. The pneumatic gate valve realizes the on-off or proportional regulation, and receives the control signal from the industrial automation control system to adjust the flow, pressure, temperature and other process parameters of the pipeline medium. The characteristics of pneumatic gate valve are simple control, fast response and intrinsically safe. No additional explosion-proof measures are required.
Pneumatic gate valve can be divided into two types: air open type and air close type. The air open type is that when the air pressure on the membrane head increases, the pneumatic gate valve acts in the direction of increasing opening. When the upper limit of input air pressure is reached, the valve is in full open state. Conversely, when the air pressure decreases, the valve acts in the closing direction. When no air is input, the valve is fully closed. Therefore, sometimes the air opening valve is also called the fault closing valve. The action direction of air close type is exactly opposite to that of air open type. When the air pressure increases, the pneumatic gate valve acts in the closing direction; When the air pressure decreases or does not exist, the valve shall be turned to the opening direction or fully opened. Therefore, it is sometimes called fault open type. The air opening or air closing of the pneumatic control valve is usually realized by the positive and negative action of the actuator and different assembly methods of the valve state structure.
The selection of gas on/off is based on the safety of process production. When the air source is cut off, is the pneumatic gate valve safe in the closed position or the open position? For example, for the combustion control of a heating furnace, the regulating valve is installed on the fuel gas pipeline to control the fuel supply according to the furnace temperature or the temperature of the heated material at the outlet of the heating furnace. At this time, it is safer to choose the air to open valve, because once the air supply stops, it is more appropriate for the valve to be closed than to be fully open. If the air source is interrupted and the fuel valve is fully opened, excessive heating may occur. Another example is a heat exchange equipment that is cooled by cooling water. The hot materials exchange heat with the cooling water in the heat exchanger and are cooled. The regulating valve is installed on the cooling water pipe. The cooling water volume is controlled by the material temperature after heat exchange. When the air source is interrupted, the pneumatic gate valve should be in the open position, which is safer. The air closed (i.e. FO) regulating valve should be selected.
