Pneumatic valve actuator working principle
Overview of pneumatic valve actuator:
Pneumatic valve actuator (usually called pneumatic head), also known as pneumatic actuator or pneumatic device, is a compressed air source pressure driven by cylinder, piston, gear shaft, end cover, seals, screws, etc. Pneumatic valve actuator is generally used with all kinds of valves, including opening indicator, travel limit, solenoid valve, positioner, pneumatic components, manual mechanism, signal feedback and other components. Compressed air controls valve opening, closing, opening and closing.
Pneumatic valve actuator working principle:
According to the functional form, pneumatic valve actuators can be divided into single function and double function. The dual function actuator is air switch type, that is, the ventilation is opened and closed. When the air source is lost, there is no action and it stays in situ. The single-acting actuator has spring reset function, which is usually closed and normally open, that is, the ventilation is opened, and automatically reset to the initial state when the air source is lost. Used in dangerous working conditions, it can quickly close or open the valve when the air source is lost.
When the air source pressure enters the cavity between the two pistons of the cylinder, the two pistons are separated to the two ends of the cylinder, the air is discharged through the air port, and the two piston racks synchronously drive the output shaft (gear) to rotate counterclockwise. Instead, when the air source pressure enters the air chambers at each end of the cylinder from the air outlet, the two pistons move toward the middle of the cylinder, the air in the middle air chamber is discharged through the air outlet, and the two piston racks synchronously drive the output shaft (gear) to rotate clockwise. (If the piston is mounted in the opposite direction, the output shaft will rotate in reverse)
When the air source pressure enters the middle chamber between the two pistons of the cylinder from the air port, the two pistons are separated to the two ends of the cylinder, forcing the springs at both ends to compress, and the air at both ends of the air cavity is discharged through the air port. The two piston racks simultaneously drive the output shaft (gear) to rotate counterclockwise. After the air source pressure is changed through the solenoid valve, the two pistons of the cylinder move to the middle under the elasticity of the spring, and the air in the middle air chamber is discharged from the air outlet, so that the two piston racks synchronously drive the output shaft (gear) to rotate clockwise. (If the pistons are mounted in opposite directions, the output shaft will reverse rotate when the spring is reset)
