INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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.

Jobs

Leak Test Help..

Leak Test Help..

(OP)
We've got an issue with one of our leak test sequences in work.

Here's the set up:

Main pressure - regulated - leak tester - leak tight valve (plc operated) - sealed face - welder injection moulded bottle.

After every break or at start up, we get a leak fail. When re-tested, the bottle passes and will run as expected (usually 100% efficient, give or take the odd iffy weld). It's as if the pressure build up is effecting the test somehow.

We've replaced the reg, leak tight valve, tried a like for like leak tester in there, no joy. All bungs, pipework and fittings are fine.

The leak test is an 80mbar test, decay test. So prefill of pressure to fill the volume of the bottle, fill to set point, take a measurement, stabilise for a set time, take a measurement, then result based on our set tollerances.

It's really stumping us to why, after a 10 min or so idle time, EVERY next bottle will fail the first test.

Suggestions welcome.

:)

RE: Leak Test Help..

Perhaps it because gas gets cooler when it is expanded through a pressure regulator. Repetitive testing allows the tubes to the bottle to cool so that test gas will tend to expand slightly in the bottle as it warms. This will cancel the slight pressure loss of the bottle expanding from pressure increase (a creep effect).

For the first test after idle time, the tubing to the bottle has not reached an equilibrium temperature.  

RE: Leak Test Help..

You didn't state what volume constitutes a "leak" but could it be that a hose or some other component is taking a set? During the 10 minute break it could relax back to its natural shape, then during the first test is deforms causing a false reading?

Slim chance, but a thought.

ISZ

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!


Resources


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