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Thread: Install a water drain spigot in an air compressor tank

  1. #1
    Join Date
    Dec 2016
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    Atlanta, GA, USA
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    Default Install a water drain spigot in an air compressor tank

    I have an air compressor with a tank that is from the 1970s. It has little use, but when I need it, I need it. The problem is the drain plug has become unmovable, probably from rust. I am considering drilling through the plug, threading the hole, and screwing in a drain spigot I can open and close. The maximum air pressure ever used is 150 psi. I would love to hear the opinions of everyone if this is feasible and if so, recommend a spigot.

  2. #2
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    Jan 2014
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    sounds fine to me. I put a T with a close nipple in the bottom of my upright, and screwed the original drain valve into the bottom of that. Then I put a long nipple in that with a ball valve on the end. I still have to get down on one knee to drain the valve, but no more wrenching my shoulder out to reach under the tank to drain the water. I drain mine every morning as part of my start up routine. Put an elbow with a long nipple and a ball valve on my roll around for the same reason. Much easier to bleed off water.

    Use whatever you have to make your job easier.
    *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

  3. #3
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    Remove the water that is in the tank somehow, then pour some penetrating oil in there so that it sits on top of the drain plug. Wait a day or so and see if you can unscrew the plug. Add pressure to the tank again to help the penetrating oil.
    Work hard play hard

  4. #4
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    S.E. MI, Metro Detroit
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    Install a remote valve.
    https://www.amazon.com/Compressor-Mo...70_&dpSrc=srch
    No more bending over.
    Larry

  5. #5
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    And drop a couple sodium hydroxide pellets in every so often. That will keep the rust down.

    Just make sure you are not going to get a spray of water out of the air hose or the drain.... might not be nice.
    1601

    Keep eye on ball.
    Hashim Khan

  6. #6
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    May 2013
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    Lancaster County PA
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    I put a brass street ell in the bottom so I don't have corrosion problems with it in the future if it needs to be removed. Then as Bob La Londe did added a long stainless nipple so the ball valve is easy to get to.

  7. #7
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    Since 1970 and never been drained? The first thing to do on a new air compressor install a bottom drain line, with a ball valve out where you can reach. I always use brass fittings, and never need to worry about a pipe nipple rusted. My guess when you remove whatever access fitting you can get to, the tank will be nearly full of water!

    Good luck getting the old fitting out at the bottom, the suggestion with penetrating oil and a few days to soak is a good one, and my suggestion at least a 18 inch pipe wrench.
    Retired - Journeyman Refrigeration Pipefitter - Master Electrician - Fine Line Automation 4x4 Router, MakerGear M2 3D printer- 20 Watt Ray Fine Galvo fiber laser, LightObject 40 watt co2 Laser Engraver

  8. #8
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    Mar 2013
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    West coast of Canada
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    Interesting that you should bring this up now. I just serviced my air compressor yesterday. It is a portable that is permanently connected to the shop air system.
    I disconnected it and pulled it out to check everything, and change the oil and top up the air in the tires. While I had it out I opened the air tank drain. To my surprise it was perfectly dry.
    It has been pretty warm and dry around here lately but I don't think I have ever opened the drain cock and got nothing but air out before. Some times it is days before I turn the compressor on again.
    It takes quite a while to run the tank down if you just blow off the odd thing now and again.
    While I was at it I removed the drain cock which is a 1/4 NPT drain cock you would find in a vehicle radiator. I cleaned it up and resealed the threads before putting it back.
    Larry

  9. #9
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    Nov 2013
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    My 80 gallon vertical tank had a needle valve in the center of the bottom. Difficult to reach. I finally had enough of it and replaced it with a street ell and a long nipple (10", maybe), both brass. On the end of the nipple is a ball valve with a 2" long handle that I can operate with my toe. My knees are much happier.

    -js

  10. #10
    Join Date
    Dec 2016
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    Atlanta, GA, USA
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    Thanks for all of the help guys! I like the idea about the remote valve. I may do that. This compressor is an old Sears with a tank mounted horizontally. The pipe type drain plug is mounted on one end a ways up from the bottom of the tank so you have to tip the entire compressor up to pour any water out. I would like to drill the new hole, not through the existing plug, but on the bottom of the actual tank and install that remote valve. Anybody see a problem in that?

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