Home Air Compressor Tank Drain Modification

When I got my 30 Gallon air compressor, I knew that I would have to occasionally drain the tank of condensation.  But draining the tank with the provided stopcock was a pain and a better device was needed. 

The tank is carbon steel and even with a corrosion allowance, the thought of my tank rusting from the inside out just didn't sit well with me.  I wanted it to last as long as possible.  To make it last as long as possible, I needed a way to drain the tank, drain if often and drain it easily.  The method of draining the tank provided by the manufacturer was a pain at best - ie a stopcock at the very bottom of the tank (see picture).  Having to crouch down and dig thru the spider webs every time I needed drain the water out from the compressor was less than desirable (i'm no sissy, but sometime the little critters give me the willies).

Do I really have to make a disclaimer here about how to not mess with stuff that you don't know how to do like pressurized and electrical systems?  I guess so - PROCEED AT YOUR OWN RISK.  READ THE MANUALS.  CONSULT THE STARS.  TAKE A CLASS.  SPEAK TO A SPIRITUAL DIRECTOR.  DO WHAT EVER IT TAKES TO NOT KILL, MAIM OR OTHERWISE HURT YOURSELF. OR OTHERS.

Step 1: The Valve

 I knew that a quarter turn ball valve would be the best item to use to replace the current valve.
I wanted to put the valve where I could reach it easier, so that meant installing some piping.  I ended up running it out to one of the legs for protection and ease of operation.

I went with flared copper tubing because the copper was corrosion resistant, you can flare it which makes for easy installation and the flare tool was relatively inexpensive.  Another nice thing about the copper tubing, is that the water no longer sits in the vessel, but it sits in the tubing which can handle water better than the carbon. 

The current valve was 1/4" NPT, so I stayed with that.  The assembly consisted of (in order of appearance):

1/4" MNPT by 1/4" Flare 90º
1/4" Copper Tubing
1/4" Flare x 1/4" MNPT Adapter
1/4" quarter turn ball valve - 1/4" FNPT x FNPT
1/4" MNPT x Hose Barb 90º (so the water can be run else where - I just let it blast on the floor)
Zip Tie

Don't forget your teflon tape!

Step 2: The Actuator

I put the valve in and then realized that the setup still needed something.  I was still having to crouch down to get at the valve.   It needed something that could allow me to actuate the valve from a standing position.  It needed an actuator arm.  A simple dowel rod would do.  How it was attached to the valve was shown in the previous step.  I also wanted to have a handle to try and make it look good.  But I did not have any large stock nor a lathe.  So I glued some small scraps of 1x4 together and put it into my drill press.  I used a wood rasp to shave the body down and sand paper to clean it up.  Actually came out decent for an on the fly build.  Sprayed it down with several coats of clear coat and is still going strong for over 5 years.

Well, this how I did it.  Your setup will probably be different but the main thing to learn from this is that if you build it so that you use it, you will USE it and your tank will last a long time.

I think I probably spent $30 or 40 on this  ( but that's including the flare tool).  It's been a while since I did this so don't remember exactly.

Pretty easy if you are familiar with running pipe and fittings.

Pax yall.



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    9 Discussions


    3 years ago on Step 1

    I made mine in a similar manner, but with a ball valve for under sink. It has a 1/2" NPT input and I used a 1/2 " MIP to 1/4" FIP adapter and a 6" copper nipple to the right angle adapter in the bottom of the tank.

    2015-07-21 17.47.01.jpg
    1 reply

    Reply 3 years ago on Introduction


    I still get "clean" water out of the spout - so it looks like my copper tubing is doing the trick.


    5 years ago on Introduction

    Great idea. I like what charlieb000 says about why it might help prevent rust...have you noticed whether the water that comes out this way is less rusty?

    3 replies

    I don't think I've ever seen rust come out of there. I will go check it later and take a pic of the drain area.


    7 years ago on Step 2

    this address another problem i see, the long tube allows all the water to drain into the pipe before you shoot it out (resovior), rather than needing to leave the under-tap open and wait for the drips to evacuate with the air. i tell others about this but nobodys interested.