×
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!
  • Students Click Here

*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

Jobs

water in air cylinders

water in air cylinders

water in air cylinders

(OP)
In our plant we are getting moisture buildup in some small air cylinders
The plant air is dry down to -14F (dew point?)
Any idea how to vent these cylinders?
We tried an inline vent but that didnt seem to help very much
Is the expansion of the compressed air causing condensation?

Terry

RE: water in air cylinders

Depending on what type drying system you are using you could be getting a little slippage of moisture.  Depending on your physical constraints and conditions expanding air could easily get to -14°F.
Our dry air and instrument air system used -40°F air.

RE: water in air cylinders

TJTN:

Just stating a temperature as a Dew Point doesn't accurately describe the water content in a gas.  You must state the reference pressure.  Sometimes the pressure is assumed to be atmospheric; but at other times what is meant is the system's operating pressure.  It makes a big difference and that is why all engineers should state their reference pressure when citing a Dew Point in a gas.

If your dew point of -14 oF is referenced at its operating pressure it is still dry enough to eliminate any water condensation in the air line.  Your dew point meter is either busted or your drying system is not working and someone is not taking dew point samples.  If your -14 oF dew point is actually correct, it is impossible for you to condense any water inside the air pipes unless you cool the pipes less than -14 oF.   Expanding compressed air will cause cooling (I doubt you could exceed the -14 oF), but that is outside of the air lines - not inside.  So your question is not valid as a possiblity.

Once expanded and cooled, your air is no longer compressed air and useless to transport or employ elsewhere.  Are you located on the Alaskan North Slope?

I don't consider -14 oF as a very good dew point.  I set my minimum dew point for instrumentation at -50 oF; but that's me.  

RE: water in air cylinders

Fix the leaks in your piping.

At every point where air is leaking out, by the laws of diffusion, atmospheric water vapor is diffusing into the pipeline.

(Editorial comment:  I am a mechanical engineer, so this whole concept is mind boggling to me.)

Story was related to me of a young engineer (also an acquaintenance) who carefully engineered and installed a minus 40°F refrigerated dew point air dryer at the power house of a large southern kraft paper mill, and who, to his dismay, kept getting complaints from the papermakers several thousand feet away in the machine room that their compressed air was wet.  Couldn't be, he said.  He knew what the dryer was producing.

Some old wise engineer put him onto the leak problem, and once they were chased down and fixed, the problem went away.

rmw

RE: water in air cylinders

(OP)
Thanks for all the replies

Facilities is telling me the -14F dew point is at atmospheric pressure
I am investigating adding a air dryer to the machines or to the air header that supplies the manufacturing line

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