Air Compressor Drain

[Avadon]

So everyone here who has a large vertical air compressor can relate to crawling under the darn thing daily or thereabouts to drain the tank by unscrewing that brass little threaded screw to let the water drain all over the floor or into the rag.

I've only had my compressor for six months and i'm already tired of doing this all the time. Anyone ever built some kind of a drain or trap where the water can run out of the base and accumulate into some kind of trap?

Even a gas on/off valve (plumbed from a 90dgs angle) sticking out of the bottom of the compressor would be easier then getting up under there and fiddling with that screw.

What can I do to invent something better?

[Brian D]

No need to invent something, they already exist.
Go to McMaster Carr or another industrial supply catalog and look up compressor drain valve or moisture drain valve. You can also buy assemblies that remove the oil and moisture out of the air and self drain when it accumulates in the bowl.

If you don't want to spend the money to do it "right", you could always just buy a pilot operated normally open valve and plumb it into the tank. When you loose air pressure in the tank or "pilot pressure", the valve opens and lets the moisture out.

[Bentiron1946]

I bought a kit at Harbor Freight for my little 2HP air compressor because I kept forgetting to drain it. Works fine.:cool:

[HWooldridge]

I put a nipple and 90 degree ell on the bottom with a ball valve at the end of the line. It's a simple task to crack it once a week to blow off the condensate - and I live in a very humid climate so once a week equals a quart or two of water.

[orgtwister]

i used a air tank drain valve from a tractor trailer tank has ring you put a cable or rope on and just give it a pull

[Avadon]

No need to invent something, they already exist.
Go to McMaster Carr or another industrial supply catalog and look up compressor drain valve or moisture drain valve. You can also buy assemblies that remove the oil and moisture out of the air and self drain when it accumulates in the bowl.

If you don't want to spend the money to do it "right", you could always just buy a pilot operated normally open valve and plumb it into the tank. When you loose air pressure in the tank or "pilot pressure", the valve opens and lets the moisture out.

Yah I want to do it right and perserve my compressor for a long time. I looked at all those on mcmaster carr stuff you said.. and after talking to MSC and Mcmaster Carr as well as Wilkerson it turns out this McMaster-Carr Compressed-Air-Activated Moisture Drain Valve 4919K13 $49.00 is exactly the right thing.

I can even put a hose off the exit of it to my washing machine drain and i'll never have to worry about draining my tank again

Thanks for the help all!

[Mike Ameling]

One note on those drain valves. Like anything that is supposed to be "automatic", check it occasionally. They usually work without problems, but it's just a good practice to check them every once in a while.

Just part of that normal ... preventative maintenance stuff.

Mikey - that grumpy ol' German blacksmith out in the Hinterlands

[Charlotte]

Just a thought, remember to check the oil level in your compressor regularly. Not having to drain it means you might not pay as much attention to it as needed.

[Avadon]

I installed the Air-Activated Moisture Drain Valve 4919K13 from mcmaster carr. It's pretty impressive. Essentially you remove the petcock valve from under your compressor, where you normally would drain it, insert a threaded nipple, then attach an 90dg elbow onto that. Now you can either extend it out or just leave it under the tank. I left it almost all under tank but it was tight clearance. From the 90dgs elbow you'll want to go into an on/off valve and then you go into the moisture drain valve and then from the drain valve you just hook its exit up to a threaded barb which is gonig to connect to some hosing/tubing which will lead to a bucket or a sink, in my case the washing machine drain. Works like a charm. Every couple of minutes it purges any water at the base of the tank. Don't ask me exactly how it does this but it works well.

Now you virtually never have to drain your tank ever again which is nice because you can keep it always full. Before I had to completely unload the tank or use up the air inside it with a tool. Kind of annoying to have to remmeber to do that every day or so and then get under their and unscrew the petcock and splash all the water into a rag, which inevitably gets all over the floor. This way is much cleaner and more professional. Hopefully more people will try this. Whoever came up with the idea was definitely onto something.


I do my compressor oil every 5-6 months and that is plenty.

[jimmy seale]

also remember. in cold/freezing weather to put a bit of methanol in the air system.it helps with line freeze, condensation freeze, and mix's with it to keep your tank from rusting.

[Compress This]

I would check out the Ingersoll Rand air compressors at Air Compressors Ingersoll Rand | Rotary Screw Industrial Compressor Parts

[acoop101]

I'd talk to your local truck shop. Trucks with air brakes have a mechanism that once the air brake tanks come up to preasure this valve collects all of the condensate, oil and any other liquid that has built up in the tank and expells it with a little bit of compressed air. I'm not sure if this is pressure operated or if it's electronic but it should be a simple install.

[johnptc]

I installed the Air-Activated Moisture Drain Valve 4919K13 from mcmaster carr. It's pretty impressive. Essentially you remove the petcock valve from under your compressor, where you normally would drain it, insert a threaded nipple, then attach an 90dg elbow onto that. Now you can either extend it out or just leave it under the tank. I left it almost all under tank but it was tight clearance. From the 90dgs elbow you'll want to go into an on/off valve and then you go into the moisture drain valve and then from the drain valve you just hook its exit up to a threaded barb which is gonig to connect to some hosing/tubing which will lead to a bucket or a sink, in my case the washing machine drain. Works like a charm. Every couple of minutes it purges any water at the base of the tank. Don't ask me exactly how it does this but it works well.

Now you virtually never have to drain your tank ever again which is nice because you can keep it always full. Before I had to completely unload the tank or use up the air inside it with a tool. Kind of annoying to have to remmeber to do that every day or so and then get under their and unscrew the petcock and splash all the water into a rag, which inevitably gets all over the floor. This way is much cleaner and more professional. Hopefully more people will try this. Whoever came up with the idea was definitely onto something.


I do my compressor oil every 5-6 months and that is plenty.

have been using these for about the last 5 years .. they are great

you get used to hearing them drain and you know they are working fine :)