Pneumatic valve, emergency switch

The fault switch of this pneumatic valve is not determined by the pressure of the instrument air supply. What determines whether a valve operates in fault-open or fault-closed mode is based on considerations such as design, manufacturing processes, and safety. In other words, a fault switch specifies the state in which the valve will be when a fault occurs – for example, if the valve loses power suddenly or if the air supply is cut off. There is also a mode called fault retention, in which the valve remains in its original position and does not move after a problem arises

This post was last edited by CHANGBAISHI on 2020-11-8 09:36. The fluid flowing through the valve exerts a certain pushing force (or restraining force) on the valve core (valve disc); an external force greater than this force acting on the valve core is required to achieve a certain degree of opening. Typically, the pressure supplied by the instrument air source is sufficient to drive the valves within a certain range, but the force exerted by the fluid inside each valve on its valve element varies. Some valves operate when the value is below the specified range, while others may not operate if the internal load is low. Therefore, this issue still needs to be based on the specified pressure range; one cannot rely on luck. As for what triggers the valve to move, it is mainly the solenoid valve that controls the instrument air supply; by losing or gaining power, this solenoid valve regulates the on/off state of the instrument air supply, thereby controlling the degree of valve opening. The instrument air supply must be maintained at a stable pressure. For reference.

Fault on/ Fault off; by ‘fault’ is meant a situation in which the pneumatic control valve loses its pneumatic signal due to a fault. It could be a broken air supply pipe, a malfunctioning electrical valve actuator, a solenoid valve that closes the air circuit, or a loss of pressure in the actuator of the pressure-relief pneumatic control valve, among other things.

Depending on the choice of actuator, the size is set by the manufacturer; for example, in the case of pneumatic on-off valves: 1. The actuator calculates torque based on 4 bar; choose an actuator with a higher gear for upward movement. 2. If the actuator is capable of overcoming the differential pressure to ensure proper operation at a minimum air pressure of 3 bar, then it should be set to 3 bar. (If the wind pressure is not sufficient to move the valve into position, then it should be moved to a safe position.) The control valve and valve actuator specify the required \"minimum operating wind pressure\", which can be used as a reference.

This valve indicates the pressure range of the purge air. A regular valve works fine with 2.5 kilograms. For larger valves, 3 kilograms is no problem at all. In my factory, many cut-off valves operate at a wind pressure of 3 kilograms; later on, since this value was considered too low, the pressure was gradually increased.

Minimum dynamic wind pressure; I’ll go to the site to check it another day. Thank you for your advice

The general design will select an air switch or air control valve based on the requirements of the production site