×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Pre-tension in Actuator Spring of Pneumatic Control Valve

Pre-tension in Actuator Spring of Pneumatic Control Valve

Pre-tension in Actuator Spring of Pneumatic Control Valve

(OP)
In Fisher control valve, there is no OEM instruction to pre-tension the actuator spring by rotating the handwheel before calibrating the actuator travel against pneumatic pressure. Is it right practice to pre-tension the spring ?

Daren!

RE: Pre-tension in Actuator Spring of Pneumatic Control Valve

No it is not the correct practice. The IOM for diaphragm actuators linked below specifically mentions how springs should be pre-tensioned in the Discussion of Bench Set section on page 7. This procedure is to be performed before mounting, and once it has been performed addition spring pre-tension is not required.

https://www.emerson.com/documents/automation/instruction-manual-fisher-667-diaphragm-actuator-sizes-30-30i-76-76i-87-en-122368.pdf

RE: Pre-tension in Actuator Spring of Pneumatic Control Valve

(OP)
What it says "some spring compression is required to move the diaphragm to the bottom of its travel" It indicates some pre-tension of spring before applying air pressure?

Spring Verification , Page 7

Daren!

RE: Pre-tension in Actuator Spring of Pneumatic Control Valve

Yes, it is stating that for the particular actuator, which is a spring close actuator, it requires some spring tension to be applied in order to reach the full down travel. The diaphragm will push the actuator stem slightly upward without spring tension. Refer to Figure 2 on page 3. I believe it would be the opposite for a spring open model.

RE: Pre-tension in Actuator Spring of Pneumatic Control Valve

As SPDI310 says it is quite simple. It's all about a balance of forces in each direction. Think about is as a regulating valve that sometimes, without pneumatic pressure, has to go to closed position. No pre-tension, no force to hold the valve in this end poition.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login



News


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close