What are the advantages and disadvantages of double-acting and single-acting pneumatic ball valve actuators?
According to the engineers of Weidun VTON, their advantages and disadvantages are as follows.
1. There is a return spring in the single-acting pneumatic actuator, which together with the ball valve forms a single-acting pneumatic ball valve. When there is no compressed air, it can be automatically reset. The key process control position needs a single-acting pneumatic ball valve, which can form interlocking control with the solenoid valve to cut off the pipeline in time and ensure the safety of production equipment.
2. There is no return spring in the double-acting pneumatic actuator, so when there is no compressed air, it stays where it is, and it can't make actions conducive to process safety. It is used where the state of the control switch is not important. When the air source fails, the opening or closing of the pneumatic ball valve will not adversely affect the control system, so a double-acting pneumatic ball valve can be selected.
3. When a single-acting pneumatic ball valve is matched with a ball valve with the same caliber, the cylinder diameter should be increased, and a return spring should be installed inside, which is higher than that of a double-acting pneumatic ball valve. When selecting, the cost and demand should be considered comprehensively.
According to the experience and summary of Weidun VTON, how to choose single-function or double-function imported pneumatic ball valves mainly includes:
Pneumatic actuators are divided into double-acting and single-acting. Single-acting pneumatic actuator (there is a spring in the actuator, which will automatically reset when the air source is lost to provide power to restore the ball valve to the initial open or closed state). If the double-acting pneumatic actuator is selected, the pneumatic actuator will lose power, and when the air source is lost, the valve position will remain unchanged. Therefore, if it is necessary to reset the valve automatically in case of gas loss, please choose single-acting pneumatic actuator, if not, please choose double-acting pneumatic actuator.
The difference between a single-acting pneumatic ball valve and a double-acting pneumatic ball valve is that there is a spring in the single-acting cylinder, but not in the double-acting cylinder. Single-acting pneumatic ball valves can be divided into two types: air opening and air closing, which can protect the air source, while double-acting pneumatic ball valves can keep the air source in place.
As far as its price is concerned, it varies according to the size of the cylinder. If it is a small order, the price difference is not too big, and the large order is more expensive.
Single action: one side of the cylinder piston is spring, and the other side is instrument air. -When the valve stops the instrument wind, the piston will be driven by the spring force to make the valve completely closed or completely opened.
Double-acting: there is no spring in the cylinder, and both sides of the piston are filled with instrument air. The valve itself does not say that the air is turned on and off, and the opening of the air cut-off valve remains in the original position.
Double-acting pneumatic actuator means that when the valve is ventilated, the pneumatic actuator starts to rotate to open the valve. When the valve is about to close, the other side can be ventilated to close the valve. It is reset by the cylinder and can only be kept in place when the air source is lost.
Single-acting pneumatic actuators opens the valve under ventilation, and automatically closes the valve without ventilation source. Single-acting pneumatic actuator is automatically reset by spring, which is generally used to transport combustible gas or liquid beyond the figure under dangerous working conditions. When the air supply is lost and an emergency occurs, the single-acting pneumatic actuator can automatically reset to reduce the danger, while the double-acting pneumatic actuator is generally not easy to reset.
Single-acting pneumatic actuators are generally divided into normally open type and normally closed type.
Normally open type: ventilation is closed and gas is closed.
Normally closed, ventilated,
Double-acting valves are generally used for gas shutoff, and double-acting cylinders have no springs, so the cost is lower than that of single-acting pneumatic actuators.