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This page will provide you with the frequently asked questions about draining a compressor tank, how often to do it and reader questions and answers.
Table of Contents
FAQs About Draining An Air Compressor Tank
It is recommended that you drain your tank daily to erase water build up in the bottom of your tank. This will help you tackle rust and stop you from needing to invest in a new tank.
Yes you should certainly drain your air compressor after every use. This will stop the possibility of water building up in the bottom of the tank and corroding or weakening the inside walls.
A lack of periodic water draining can lead to condensate buildup downstream, causing corrosion to the compressed air system.
To ensure that water does not build up inside the tank and cause corrosion of the inside wall which will result in rust/debris getting into the air stream and causing damage further down the line.
Reader Questions & Responses
Drain or Do Not Drain a Compressor Tank
About draining an air compressor tank. Do it or not? I have a 60 gallon tank compressor and plan to use it occasionally in my home garage. How often should the tank be drained?
Is there any potential damage to be done if I leave moisture in the tank in freezing weather?
Thanks for your help.
To questions one, the answer is that it’s best to drain the tank after every use.
To question two, there is potential for problems. If there is water in the tank it will freeze. If any of that water gets into the air exit of the tank, it will freeze, as it will in the air lines, air tools used in the cold, etc.
Draining a large tank
While I agree that you should drain the water from a tank every night as you turn the lights out in your shop, the article referenced speaks of completely draining the air and leaving the drain valve open. With a 60 gallon tank, that can take quite a while using the 1 inch dump valve, and draining it through the water drain cock can take a very noisy long time and is very wasteful of air. So i just open it long enough to remove the water, then close it.
For my 60 gallon tank, I have found an old (non-electric and automatic) compressor tank drain valve that I hope will be a better solution. (Or maybe a different solution? ) It comes on for a few seconds each time the compressor starts and stops to drain the tank automatically.
Thanks for this. I assumed that most of the questioners on this topic are owners of smaller compressor. You know what they say about assuming?
Your comments about the time to dump a larger tank, not to mention the energy waste, are spot on.
On a few pages on my site I refer to an electronic auto-drain for compressor receivers. These are very useful devices that regularly and automatically drain the tank of water, use minimal energy, and waste as little compressed air as possible.
I had not heard of the product you refer us to, and it is indeed very interesting.
Thank you again for your useful comment, and for visiting my website.
There are two common types of auto-drains. One is a solenoid with an electronic timer that opens the valve for a short preset period every so many minutes or hours.
The other is connected to the tube that runs to the pressure switch and opens the drain valve every time the compressor shuts off, and does not require any electricity to operate. They’re both effective.
Mine’s only a 21-gal “smaller” unit and as such also comes with a 1-stage motor, which I know from experience the longer it runs, the hotter it gets.
As a rule they can run continuously for 15-20 minutes without too much trouble, but let it run much past 1/2 hour and you could be asking for a fried commutator (that would be the wound central axle of the motor, requiring a motor replacement).
For this reason I always monitor the unit and as I use it daily for maybe 5-10 minutes I simply can not afford to drain it completely.
With light daily use there simply isn’t enough water build up, hence I drain it every so often and as another person pointed out, only until the water stops coming out.
This takes practice one, and if you decide to follow my advice you take your chances with a possible corroded tank interior two, but then again way I see things either way we’re taking our chances (a fried motor costs as much as the entire unit, $140+).
So, that’s just my .02
If you have any questions regarding draining the compressor tank then please comment below with a photo if applicable so that someone can help you!
I plan on mounting an onboard air compressor with a 2.5 gallon tank under the bed of my truck. I understand I need to drain frequently but I am looking for a good way of doing that without having to climb under my truck each time. Will a hose hooked up to the bottom of the tank but ending at a point higher than the tank still drain well?
You can do that, and it will work so long as there’s pressure in the tank.
Trucks with airbrakes sometimes use a spring loaded normally closed valve and run a cable to the body work so you can just reach under and pull the cable. This minimizes getting rusty, oily water sprayed all over yourself.
Either way, you’re really supposed to collect that stuff and dispose of it properly.
I’m curious; what you plan to use for a pump?
Awesome thank you. I picked up a Viair 10007 kit with a 2.5 gal tank and I plan on putting it in the dead space between the body panel and the bed side (compressor on one side, tank on the other). Thanks for the heads up about disposal. I’ll probably just run the drain valve to inside the gas flap and drain it into an empty water bottle or something when I need to.
Cool. Take pix and post your work, if you like!
Well Doug, I finally finished my install, while I was originally going to remote route the drain valve I was concerned about the hose being the lowest point on my vehicle as well as kinking so I opted to mount it directly to the tank. Turned out pretty ok imo.
You gonna use it just for tires, or did you get an air horn, too? 😉