Installation sequence of solenoid valve and filter pressure regulator
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The air passes through the filter, pressure regulator, valve positioner, and solenoid valve before entering the actuation mechanism. Why are both on-off valves and control valves designed with the solenoid valve adjacent to the actuation mechanism? What is the reason for this? Is it to enable rapid switching of the valve?
The solenoid valve is located between the actuator and the cylinder (diaphragm head); its function is to supply or cut off (while releasing) the air supply to the cylinder. Placing the solenoid valve behind the actuator results in a faster response time compared to placing it in front of the actuator.
It depends on the function of the solenoid valve being installed. Most solenoid valves are installed to provide interlock protection. For example, in the case of control valves equipped with positioners, solenoid valves are installed to enable the control valve to shut off and open rapidly. The purpose of this is to enable the valve to act quickly in case of process abnormalities, turning the control valve into a shut-off valve. The positioner is a pneumatic control instrument that contains components such as air reservoirs for storing instrument air. Although installing the solenoid valve in front of the positioner allows it to cut off the air supply to the positioner promptly, thereby preventing the subsequent control valves and positioner from receiving any instrument air, the air reservoirs in the positioner, along with the small leakage holes and the electrical control circuits, have a significant time lag. As a result, the goal of quickly shutting off the valves is not achieved.