water in air cylinders

[TJTN]

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

 

[unclesyd]

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.

 

[Montemayor]

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.

 

[rmw]

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

 

[TJTN]

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