Sanitary Valves: Pneumatic or Electric Actuators

Butterfly Valve with an Electric Actuator

Butterfly Valve with a Pneumatic Actuator

Air Actuators or Electric Actuators, how to choose the right type of actuator for sanitary valves.

In Malaysia's food, beverage, and pharmaceutical industry, the most common sanitary valves are powered by air and electric actuators.

Pneumatic Actuators come in Single Acting or Double Acting types, both are able to open and close sanitary valves, but operate differently.

Single Acting Air Actuators are powered by air and spring. When air is supplied, the actuator opens the valve, and the spring closes the valve when air supply is cut off (normally closed actuated valve). Similarly a normally open actuator closes the valve when air is supplied, and the spring opens the valve when air supply is cut off.

Double acting pneumatic actuators on the other hand requires air supply do not include a spring, and require air supply to open and close the valve. When air supply is cut off, the valve remains in the last position, unable to open or close automatically.

So, when to use single acting or double acting actuators?

For applications where the sanitary valve is required to become closed or open in the event of air supply loss (such as a shut down valve), it is better to use the Single Acting Actuator, because of its simplicity and reliability in design.

For applications where the valve is required to remain in its last position in the event of air supply loss (such as a production choke valve), it is better to use a Double Acting Actuator, because it requires pressure to either open or close.

Single vs Double Acting Actuators

Electric actuators are powered by electricity and is commonly used when there is no available air supply.

They require electricity to open and close the valves and do not come with springs such as the single acting

pneumatic actuators. It is also relatively easier to wire and integrate to your current control systems.

Electric actuators are generally more expensive than pneumatic actuators. They act much slower than pneumatic actuators.

Also, an electric actuator is considered to be more risky because when it stalls, it might cause excessive current draw and hazardous working environments.

Finally, electric actuators are available for quarter turn valves such as ball or butterfly valves, while the pneumatic actuators

can be attached to quarter turn valves and linear valves such as diaphragm and stem valves.

To conclude-

1. Pneumatic actuators are cheaper than their electric counterparts.

2. Some pneumatic actuators come with fail safe springs (single acting) to ensure the required valve position in the event of air supply loss, while electric actuators will always require electricity to operate.

3. Pneumatic actuators are considered to have a simpler design and therefore more reliable

4. Pneumatic actuators are available for quarter turn sanitary valves (ball and butterfly valves) and linear sanitary valves (diaphragm and stem valve), electric actuators are only available for quarter turn valves.

5. Electric actuators do not require air supply to operate.

6. Electric actuators are easier to wire than their pneumatic equivalents.

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There you have it, the difference between electric and pneumatic actuators.

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