1. How to select pneumatic actuator?

In modern working conditions, the use of pneumatic actuated on-off valves instead of manual valves can greatly improve the production efficiency of its products and the safety of production equipment.

Regarding the selection of pneumatic actuated valves in the production of polyethylene products, we will introduce the selection of pneumatic actuators.

Pneumatic Actuated Valve is mainly composed of actuator, valve body and pneumatic actuator accessories. In the production of PVC, we must select thepneumatic actuator valves that meet the pressure, temperature and corrosion conditions, and also equipped with explosion-proof solenoid valves and explosion-proof limit switches and other accessories.

2. Selection of pneumatic actuator:
Currently the main implementing agencies are:

(1). Cylinder piston actuator. The cylinder-piston actuator is to push the piston and connecting shaft to change the valve position of the valve body through the compressed air in the cylinder to form a certain pressure.

There are two types of cylinder piston actuators:

• Single acting N/C, Air to open, interrupt air to close, air failure to close.
• Single acting N/O, Air to close, interrupt air to open, air failure to open

It is suitable for most valve bodies and is a commonly used actuator;

• Double-acting, Air to open, air to close, air supplier failure to keep the current position.

It is a springless piston mechanism. Because there is no spring to offset the thrust, the output force is large. It is suitable for large-diameter, high static pressure, high pressure differential valves and Butterfly valve.

(2). Multi-spring pneumatic daiphragm actuator.

The advantage of the multi-spring actuator is that it can easily adjust the number of spring groups to realize the use of different air source pressures and spring ranges, and the combination is flexible. The disadvantage is that due to the lower pressure of the diaphragm, coupled with the balance spring, which cancels most of the force, the output force is smaller.

Sometimes customers request to choose single-acting pneumatic actuators. This is why our manufacturers should ask in time whether single-acting pneumatic actuators use air to open or air to close. Because there are normally closed and normally open types in the valve pipeline, it is implemented The device is also divided into air-opening and air-closing. According to our usual experience, air-opening is used on normally closed valve pipes, and air-closing is used on normally open valve pipes.

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