Specification for Actuator??? 2

[bmoorthy]

While API 6A gives some requirement for Actuator, other Valve standards/Specification does not go into details of actuator and the basic minimum requirement for actuator.

For Example when procuring ESDV, SDV and MOVs the Actuator requirements are never properly specified by the user (Including the likes of Shell and Exxon and Total) and the users and the contractors are fully dependent on the acuator supplier's disposal since the valve standards do not delve into this.

The query: Are there ISO or BS EN or ANSI standards that deals with the actuators?

I am trying to develop a general requirement for actuator for my company and am collecting and collating data on actuator (While API 6A gievs reference to some ISO for actuator, am not sure whether the requirement can be extended to other normal valves)

Any and all information are welcome.

 

[rmw]

You need to define your service for the actuator. Modulating service is usually considered to be in the range of 3600 starts per hour (constantly moving actuator) while positioning is in the range of 5-600 starts per hour and on/is just that, rarely moves.

The actuator manufacturers will tell you quick if their actuator IS made for the service that you specify. Beware of those who won't guarantee the starts per hour that you need.

But in answer to your question, I know of no standard that states that-just empirical data.

rmw

 

[bcd]

The ISO organization made an attempt to create some very basic actuator standards. Drafts were created but to my knowledge, they never advanced into standards. Probably could not get all the members to agree. There is simply too many widely different applications and actuator types to condense requirements into a standard. The requirements would have to be so open for all the committee members to agree in a vote that the standard would not be of much value.

Currently actuator requirements exist in end user standards based on their experience in particular applications.

 

[Ashereng]

For on/off valves, what specifications are you thinking of?

Some specifications that I have included in the past:
- closing speed
- requirement for a speed controller
- torque of the actuator to be a minimum of 1.5x the max torque to close the valve
- number of starts/hr
- type of actuator


"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?

 

[JLSeagull]

For pneumatic actuators you need to advise the actuating medium such as instrument air or process gas as well as the minimum pressure so that the forces used for actuator sizing work at the minimum pressure. Consider a pressure regulator set at the minimum or at least well below the maximum pressure rating of the actuator. If the supply can exceed the actuator rating include a PSV in the actuator controls to protect the actuator.

For emergency shutdown valves the actuator requires a spring that opposes the pneumatic force to close the valve upon failure of the pneumatic medium. This is available with diaphragm and single acting piston actuators. Double acting actuators and vane actuators lack a force balance means to close a valve for emergency shutdown. Electric motor operated valves and electro-hydraulic actuators lack the force balance to move the valve to a failure position upon loss of the energy force.

Consider position switches to indicate the valve position and perhaps include the position status in the logic to alarm the difference between the command and actual position.

Quick exhaust valves are normally required for valves NPS 24 and larger.

Offshore actuators and nasty plant environments often use a closed pneumatic loop that keeps instrument air on the actuator instead of inhaling the atomospheric air when cycled.

Lots more issues exist. Few industry standards exist.

 

[JLSeagull]

Although I rarely use the water works standards, review the AWWA C540-02 text for some ideas.

 

[maocba]

You can have a look at german code KTA-3504: Electrical Drives of the Safety System in Nuclear Power Plants.
Here you can find the basic features for and actuator.
Visit this page and click in "KTA 2000" there you will down load free the code KTA-3504.

http://www.kta-gs.de/

 

[leecoop]

A couple of clarifications/comments---
Ashereng: You mentioned "torque", but remember, you might have a linear actuator which would require "thrust"

A linear pneumatic piston actuator is very common for globe control valves.

JLSeagull: Recall, you can have an air fail system used in conjunction with a double acting actuator (true--it is not as fail safe as a spring) Also, you can have an electrohydraulic actuator with a spring in it.

it is what has performed well in various applications

 

[JLSeagull]

The common use of a double acting or pilot operated piston pertains to economics for control.

I am aware of a company that uses double acting vane type actuators for critical applications such as emergency shutdown valves on offshore platform riser valves. I regard this as intentional neglegence. (Where did he get his high horse??) Perhaps I should not judge some of these decisions so harshly. Still, I recommend spring return actuators for critical applications.

 

[Ashereng]

leecoop,

I mentioned torque, because that was one example of what I had specified, for a "ON/OFF" valve.

My response to the OP is not exhaustive, nor does it include every possbile answer.

I was trying to ask the original poster to provide more information so that I can give a more useful response.

"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?

 

[mrctchlr]

You can use as guideline

prEN 15714-1 - 2007 - Industrial valves - Actuators - Part 1_ Terminology and definitions
prEN 15714-2 - 2007 - Industrial valves - Actuators - Part 2_ Electric actuators for industrial valves - Basic requirements
prEN 15714-3 - 2007 - Industrial valves - Actuators - Part 3_ Pneumatic part-turn actuators for industrial valves - Basic requirements
prEN 15714-4 - 2007 - Industrial valves - Actuators - Part 4_ Hydraulic part-turn actuators for industrial valves - Basic requirements

 

[valveman69]

When specifying Actuators for Linear Motion Valves, in general the only "critical" request is Action on Loss of Signal/Air/Supply etc. Other factors such as thrust/torque figures, stroke length, speed of travel ect are deemed by the manufacturer and based upon the process medium parameters.

The Actuator "supply" is the only other information required for calculations, i.e. Air Supply, Electricity Supply, Hydraulic Supply etc.