Actuator type for shut off valve 5

[PAN]

In my company, the actuator for shut off valve always be cylinder type. If the vendors propose rack & pinion type, our engineers always reject them.

Please advise me. I would like to find the supporting reason.

 

[JLSeagull]

aticooper,
What actuator manufacturers do you find well suited to the gate valve applications?

 

[Ashereng]

We typically go electric. So think Rotork.

Lots of actuators in a whole bunch of sizes. If you need a lot of torque, you can also gear box.

You need power though.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[leecoop]

JLSeagull,

You can use an electric multiturn actuator for gate valves if speed of operation OR failure position is not an issue. A piston actuator with a spring will allow for a failure position. You can also produce faster stroke speeds. Electric motors are also harder to maintain. However, depending on size, electric motors can be cheaper than piston type. Another possibility is electrohydraulic. It uses electric power to power a hydraulic pump to provide hydrulic fluid to a piston type actuator. Hope this helps...

aticooper

 

[Ashereng]

aticooper,

Just a question.

If an electric motor is not a good idea because it is hard to maintain, how is electrohydraulic a good idea? You now have two systems that need maintanence - electric motor and hydraulic system which may leak.



"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[leecoop]

Ashereng,

You are right. Each solution has pros and cons. Sometimes, there is no pneumatic or hydraulic power at the valve location, only electric. Therefore, you might have to use electric. Now, if you want the valve to fail, you can use electro-hydraulic. The fail mechanism can then either be a hydraulic accumulator or a spring inside the piston actuator.

 

[ScottyUK]

EH has some other advantages over pure electric driven actuators, especially on continuously modulating service where mechanical drives such as ballscrew or gearbox will suffer wear problems. The EH system allows you mount the electrically driven pump in a 'good' environment, away from excess heat, vibration, aggressive chemicals, hazardous areas, etc.

aticooper said it best with "Each solution has pros and cons."

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