How does the pneumatic control valve work?
Release time:
2024-10-30 15:16
Pneumatic control valveHow does it work?
The pneumatic regulating valve uses compressed gas (usually purified compressed air) as the power source, and the cylinder as the actuator. According to actual needs, the valve is driven by accessories such as power distribution/gas valve positioner, electric/gas converter, solenoid valve, holding valve, gas storage tank, gas filter/decompression/oil mist separator, etc. to achieve the purpose of regulation and pick up and drop the control signal of industrial automation control system, to complete the pipeline medium (such as flow) to adjust various process parameters (such as pressure, temperature and liquid level). Through the development of different periods, early mechanical, intelligent and other types. The valve positioner is the main accessory of the control valve and is usually used with the pneumatic control valve. It picks up the output signal of the control system, and then uses its output signal to control the pneumatic regulating valve. When the control valve action, the displacement of the valve stem through the mechanical device feedback to the valve positioner. The valve position status can be transmitted to the industrial control system by electrical signals or additional valve position switches, or not.
The action mode of the pneumatic control valve is to use compressed gas as the power source and the cylinder as the actuator. The valve positioner, converter, solenoid valve, check valve, gas storage tank, gas filter and other accessories are used to drive the valve to realize switch or proportional adjustment, and to transfer the control signal from the industrial automation control system to complete the adjustment of various process parameters such as flow rate, pressure, temperature, liquid level and the like of the pipeline medium. The pneumatic control valve has the characteristics of simple control, fast response and intrinsic safety, so no additional explosion-proof measures are required.
Air open type (normally closed type) refers to when the air pressure on the diaphragm head increases, the valve moves in the direction of increasing opening. When the upper limit of the input air pressure is reached, the valve is fully open. Conversely, when the air pressure decreases, the valve acts in the closing direction. When there is no air input, the valve is completely closed. Usually, we will open the air regulating valve called the fault closed valve. The direction of action of the gas-closed type (normally open type) is just the opposite of the gas-open type. When the air pressure increases, the valve acts in the closing direction; when the air pressure decreases or does not exist, the valve should be turned to the opening direction or fully opened. Usually, we call the air shut-off regulating valve a fault open valve.
The choice of gas on/off is based on the overall view of the process production. When the gas supply is cut off, whether the regulating valve is in the closed position or the fully open position.
For example, for the combustion control of the heating furnace, a pneumatic regulating valve is installed on the fuel gas pipe to control the fuel supply according to the furnace temperature or the temperature of the heating material at the outlet of the heating furnace. At this time, it is better to use air to open the valve more fully, because once the air supply is stopped, the valve is more appropriate to close than fully open. If the air supply is interrupted and the fuel valve is fully open, overheating may occur.
Another example is a heat exchange device cooled by cooling water. The thermal material exchanges heat with the cooling water in a heat exchanger to be cooled.Pneumatic control valveInstalled on the cooling water pipe. The amount of cooling water is controlled by the material temperature after heat exchange. When the gas supply is interrupted, the regulating valve should be in the open position and more complete. Air shut off (I. e. FO) control valve shall be selected.
2022-12-19
Wuhan Weituo Fluid Control Equipment Co., Ltd
Address: 1706, Building D, Wuhan Living Room, No.8 Hongtu Avenue, Dongxihu District, Wuhan City
Telephone:0086-18942929031 0086-18571829295
Landline:0086-027-83612831
Fax: 0086-027-83612830
E-mail:watosong@watovalve.com
Website:www.watoer.com
