The pneumatic ball valve is composed of a pneumatic act […]
The pneumatic ball valve is composed of a pneumatic actuator and a ball valve. The pneumatic actuator is divided into double action and single action. The double acting pneumatic actuator has gear rack, piston, output shaft, sealing ring and other parts. The ball valve and the ball valve form a double-acting pneumatic ball valve. After the compressed air is turned on, the air pressure pushes the cylinder piston to move, and the output shaft rotates 90 ° C, and the ball valve is opened or closed. When the air supply is disconnected, there is no pressure in the cylinder, the output shaft stops rotating, and the ball valve remains in the open or closed position. Only after the gas source is turned on again, the action is resumed, so for the double-acting pneumatic ball valve, there is no difference between the normally open type and the normally closed type.
Single-acting pneumatic actuators and ball valves form a single-acting pneumatic ball valve. The difference between a single-acting actuator and a double-acting actuator is that it has a return spring inside it, and there is no return spring in the double-acting pneumatic actuator. When the air source is turned on, the output shaft drives the ball valve to open or close. After the air source is disconnected, it is reset by the spring drive, and the output shaft drives the ball valve to close or open.
After the normally open pneumatic ball valve is disconnected from the air source, the ball valve is opened. After the air source is turned on, the ball valve is closed. When the normally closed pneumatic ball valve is disconnected from the air source, the ball valve is closed. After the air source is turned on, the ball valve is opened. Only single-acting pneumatic ball valves distinguish between normally open and normally closed.
The selection of the normally open pneumatic ball valve and the normally closed pneumatic ball valve mainly considers the production safety of the process pipeline and equipment. When the gas source fails, the pneumatic ball valve pipeline is opened or closed, and the safety impact on the system is different, so The normally open and normally closed modes of the pneumatic ball valve should be selected according to the actual situation.