Choosing Single or Double-Acting Valve Actuators 3

This isn't a code or standard thing.

See this and


Single needs some sort of spring to return the valve position and is usual for ESD valves and many control valves where the spring either opens or closes the fail depending on your fail position (FO or FC)

Double acting is for "normal" on/off or variable position valves.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

The purpose/use of the valve, as well as the required fail position, will drive your decision.

Hi LittleInch and RVAmeche,

thanks for your help. I am new here so I'm still learning the ropes so apologies for any inconvenience. If I'm using the valve as an XV/on-off valve with Total Shut Off in case of trips, does this mean I should use spring return actuators instead of double acting?

Thanks

What's your fail operation? See the P,&I'D or ask the process engineer.

Fail closed or fail in position?

First one spring, second is double acting

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

It's fail closed. Thanks!

Every time I talk to somebody about fail safe valve actuators, I always ask - why do you care what it does when the power goes out? The ratio of times I get a cogent answer to a non-answer or "it's always been that way" answer is a very small number. So, if you want to be a pain in the butt, and really learn something, dig in your heels on the "it has to fail closed" answer, and ask "does it really?". If power fails, do the pumps fail, and so does it matter what the valve does?

Well, what if the power fails locally...?

The decision is driven by the process, operational requirements, safety, and the consequences of the various failure you might have to deal with likely or not.

For example, in some processes, valve failure has to be included in all the what if's.

Hi

I fully agree with btrueblood. Unfortunately, regardless where you’re standing (end-user/supplier/manufacturer,etc.), in valve world there will always counter questions such as ‘do you need it’, ‘why’, ‘ how(1) to achieve’, ‘how to assure how(1) for happening’ and ‘what is the (price/design) consequences’. Often not in orderly manner.
I personally is a believer that there is no such things as super-valve. To make a super valve, then it would requires multiple accessories and also periodic maintenance activities (which in some occasions, might be difficult).

Your statement is quite intriguing: 10” ball valve, metal seated (due to 290 degC) hence bigger friction between ball and seat, acting as XV (Control Valve), but also act as ESD, and tight shut off (Leakage rate class B as per ISO 5208).
It is a very challenging goals, that often will not succeed (even by some well known brands of ball valve).
Do you need this valve more as control valve or more as ESD?

For critical control valve, it is almost always located between two manual valves. In order for operation to do IPF testing/maintenance/repair shall require. So, would suggest, no need to attribute Tight Shut off on this valve. it will bite you at some point.
Without going into technical details, 10” metal seated BV as a control valve usually requires relatively big actuator, adding (quick acting) spring(s) then usually it will be bigger. Not sure of the valve’s control range, but using pneumatic (compressible air) there is a risk of ‘time response’ and/or ‘hysteresis’ between desired position (signal) and actual position.
Have I saw “air instrument” failure on pneumatic actuator and/or “solenoid valve” failure on hydraulic actuator? Yes. Hence there is IPF testing, which address likelihood of failure.

Some additional thought: a SIA (Secured Instrument Air) buffer vessel can be applied for double acting valve. Does end user like this (to buy and to install) just for sole purpose of your valve? I highly doubt.

It is not an impossible task, but it would be costly. And if it is cheaper do IPF every 6 months and/or to send someone run to close the manual valve, then would suggest to back to the discussion group of what is more important on this valve.

Success,
Regards,
MR


All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected