Question: Good day! I was hoping for some advice on how to design the demand side of an air supply system. We are located between a river and the ocean, in a non-climate-controlled aircraft hangar. About 8 months out of the year, we are at 100% humidity.
We have an air system that was installed 6 years ago or so, and all the distribution points (7 total) are deteriorated beyond repair. The compressor and 1-in. air lines seem to be in good repair still, so we should just have to replace the distribution lines. Our system is regulated to 90 psi and we do not have an option to have powered/heated condensation removal systems.
I am an aircraft mechanic by trade, so I am not well taught on setting up these systems, our facilities maintenance people say it is not their issue to fix. Any assistance you might be able to provide for a longer lasting, more reliable system would be greatly appreciated.
Answer: Sounds like you have a very wet system. It’s too bad you don’t have an option for an air dryer, a small high temperature unit, properly oversized for the heat of a small reciprocating compressor, would use less electric power than a coffee maker and take all that moisture out of your system.
You should realize the real enemy causing excess water to form in your system is heat. The hotter the compressed air coming out of the compressor, the more water contained in the air. The amount of water doubles for every 20° of higher temperature. All that water condenses out into your piping, so if you can cool down the compressor and/or the discharge air, perhaps even with a water cooled heat exchanger with groundwater cooling, and run the air through a separator or air receiver it would make a big difference. Your best bet is a refrigerated dryer though.
About your distribution piping, a good design has the main air feed going through a nice big air receiver to allow moisture to drop out and the air to cool, and have the pipes slope gently away from the compressor, with no low spots. At the end of the system, you should place an automatic float style water drain.
Any distribution lines should come off the top of the main line and goose neck down to the compressed air drop. At the bottom of the down-drop place a manual drain. Any quick connect coupling should be placed about 12-in. higher on the down drop pipe than the train.
You might want to consider aluminum piping, rather than iron, this will minimize the corrosion in a wet system. Almost all compressed air suppliers have some type of aluminum piping to offer. Ask them to help.