Selection of emergency shut-off valve actuator

The pneumatic actuator of the emergency shut-off valve is powered by compressed air to control the valve. It has the advantages of simple structure, reliable action, stable performance, easy maintenance, fire and explosion prevention, and is easy to make into a high thrust actuator. It is also inexpensive, easy to maintain and repair, and has good adaptability to the environment. The disadvantage is that to achieve control, a dedicated gas source pipeline must be laid. For double acting pneumatic actuators, they cannot return to the preset position after cutting off the gas source. For single acting pneumatic actuators, they can rely on springs to return to the preset position after cutting off the gas source. Pneumatic actuators can be divided into diaphragm type, piston type, and gear rack type according to the different ways of converting control air pressure into displacement.

Emergency shut-off valve for liquid ammonia - Shanghai Yonglong Valve Factory

Pneumatic emergency shut-off valve actuator is a piston type actuator suitable for cutting off and controlling the opening and closing of valves with a 90 ° angular stroke, such as butterfly valves, shut-off valves, ball valves, and plug valves. When compressed air enters the cylinder, it pushes the piston to move in a straight line. The piston pin and the U-shaped groove of the shift fork are used to convert the linear motion of the piston into the rotational motion of the shift fork. The rotation of the shift fork drives the output shaft to rotate, thereby achieving control of the pneumatic cut-off valve.

Selection of emergency shut-off valve actuator

According to the different types of emergency shut-off valves, they can be divided into single acting pneumatic actuators and double acting pneumatic actuators.

Single acting piston pneumatic actuator, one driven by air source and the other reset by spring during switch action; The switch action is driven by the air source, which is a double acting piston pneumatic actuator.

According to their different structures, Yonglong valve cut-off valves can be divided into single acting (normally closed) cylinders and double acting cylinders (normally open) piston types, usually determined by the magnitude of torque, with double cylinders providing greater force;

Ammonia emergency shut-off valve - Shanghai Yonglong Valve Factory

Working principle of emergency shut-off valve actuator

When compressed air enters the pneumatic actuator of the liquid ammonia emergency shut-off valve from nozzle A, the gas pushes the double piston to move linearly towards both ends (cylinder head end). The rack on the piston drives the gear on the rotating shaft to rotate counterclockwise by 90 degrees, and the pneumatic shut-off valve is opened. At this time, the gas at both ends of the pneumatic actuator valve is discharged with the B nozzle. On the contrary, when compressed air enters the two ends of the ammonia emergency shut-off valve pneumatic actuator from nozzle B, the gas pushes the double plug to move in a straight line towards the middle. The rack on the piston drives the gear on the rotating shaft to rotate clockwise by 90 degrees, and the pneumatic shut-off valve is closed. At this time, the gas in the middle of the pneumatic actuator is discharged with nozzle A.