Working principle of pneumatic control valve:
Pneumatic control valve refers to the pneumatic control valve, which is driven by air source, cylinder as actuator, 4~20mA signal as driving signal, and driven by electric valve positioner, converter, solenoid valve, position keeping valve and other accessories, so as to make the valve adjust linearly or with equal percentage flow characteristics, so as to realize on-off or proportional adjustment of various process parameters such as flow, pressure and temperature of pipeline medium.
Pneumatic control valve has the advantages of simple control, rapid response and intrinsic safety. And when used in inflammable and explosive places, no additional explosion-proof measures are needed.
Pneumatic control valve is usually composed of pneumatic actuator and control valve connected, installed and debugged. Pneumatic actuators can be divided into single-acting and double-acting types. There is a return spring in single-acting actuator, but there is no return spring in double-acting actuator. Among them, the single-acting actuator can automatically return to the initial open or closed state of the valve when it loses its origin or suddenly fails.
According to the action form, pneumatic control valves can be divided into two types, namely, the so-called normally open type and the normally closed type. The air opening or closing of pneumatic control valve is usually realized by the positive and negative actions of actuator and different assembly methods of valve state structure.
Action mode of pneumatic control valve:
Air-open (normally closed) means that when the air pressure on the membrane head increases, the valve moves in the direction of increasing opening, and when the upper limit of input air pressure is reached, the valve is fully opened. On the contrary, when the air pressure decreases, the valve moves in the closing direction, and when there is no air input, the valve is completely closed. Usually, we call the air-operated control valve a fail-close valve.
The movement direction of air-closed type (normally open type) is opposite to that of air-opened type. When the air pressure increases, the valve moves in the closing direction; When the air pressure decreases or does not decrease, the valve will be opened or fully opened. Usually, we call the gas-tight control valve a fail-open valve.
What types of pneumatic valves are available?
1, this is not accurately specified, and each manufacturer has its own model weaving method.
2. Pneumatic valve: Pneumatic valve is a valve driven by compressed air. In the current market economy environment, it is not perfect to only specify the specifications, categories and working pressure when purchasing pneumatic valves to meet the procurement requirements. Because for the sake of product competition, pneumatic valve manufacturers have made different innovations under the concept of unified design of pneumatic valves, and formed their own enterprise standards and product individuality. Therefore, it is very necessary to put forward technical requirements in detail when purchasing pneumatic valves and coordinate with manufacturers to obtain knowledge as an annex to the pneumatic valve purchase contract. Generally, this valve should be installed horizontally in the pipeline.
Above, Bian Xiao introduced the model, working principle and function mode of pneumatic control valve in detail. I believe consumers have a better understanding of pneumatic valves. In fact, if consumers want to buy pneumatic valves, it is not enough to have these, but also pay attention to maintenance and warranty. Usually, they should be placed in a ventilated place, and both ends of the passage should be blocked, which can reduce its damage and increase its service life. Bian Xiao also warned that when using, we must pay attention to the direction of the switch.