The gas regulator valve is powered by compressed air and uses a cylinder as an actuator to achieve on-off or proportional control. It receives control signals from industrial automation control systems to adjust various process parameters of pipeline media, such as flow, pressure, temperature, etc.
The air-open type means that when the air pressure above the diaphragm increases, the valve moves towards the opening direction. When it reaches the upper limit of the input air pressure, the valve stays in the fully open state. Conversely, when the air pressure decreases, the valve moves towards the closing direction, and when there is no input air, the valve is fully closed. Typically, we call air-open type control valves fault-closed valves. The air-close type operates in the opposite direction to the air-open type. When the air pressure increases, the valve moves towards the closing direction, and when the air pressure decreases or there is none, the valve moves towards the opening direction or fully open. Typically, we call air-close type control valves fault-open valves. The choice between air-open and air-close is based on the safety of the process production. When the air source is cut off, is it safe for the control valve to be in the closed or open position?
The valve positioner is used together with the gas regulator valve. It accepts output signals from the adjuster and then controls the gas regulator valve with its output signal. When the control valve moves, the displacement of the valve stem is fed back to the valve positioner through a mechanical device, and the valve position status is transmitted to the upper system through an electrical signal. The valve positioner can increase the output power of the control valve, reduce the lag of the control signal, speed up the movement of the valve stem, improve the linearity of the valve, overcome the frictional force of the valve stem, and eliminate the influence of unbalanced force, thereby ensuring the correct positioning of the control valve. The execution mechanism can be divided into pneumatic execution mechanism and electric execution mechanism, with straight stroke and angular stroke.
The installation position of the gas regulator valve should be at a certain height from the ground, and there should be a certain space between the upper and lower parts of the valve for disassembly, repair and observation. For control valves equipped with pneumatic valve positioners and handwheels, the operation, observation, and adjustment should be easy.
The control valve should be installed on a horizontal pipeline and be perpendicular to the pipeline both above and below. Generally, it should be supported under the valve to ensure stability and reliability. In special cases where the control valve needs to be horizontally installed on a vertical pipeline, it should also be supported. During installation, avoid adding additional stress to the control valve.
The working environment temperature of the control valve should be within (-30～+60℃), and the relative humidity should not exceed 95%.
There should be a straight pipe section before and after the control valve, with a length not less than 10 times the pipe diameter, to avoid affecting the flow characteristics due to the short straight pipe section of the valve.
If the diameter of the control valve does not match that of the process pipeline, an eccentric pipe connection should be used. For small-diameter control valves, threaded connections can be used. The flow direction arrow on the valve body should be consistent with the flow direction of the fluid.
A bypass pipeline should be set up for easy switching or manual operation, allowing for inspection of the control valve without stopping the process.
Before installing the gas regulator valve, all foreign objects in the pipeline, such as dirt and slag, should be thoroughly removed.