I get a lot of questions about whether or not it’s a good idea to add-an-air-tank to a compressor, or is it even possible? The answers to both questions is… yes! With some qualifications, of course.

One way you can improve the function of a small air compressor is to add an air tank, building a greater reservoir of compressed air for you to draw on when you are using an air tool that outstrips the capacity of the compressor.

First Off

Pull the plug on your compressor, and void any compressed air in the tank to atmosphere by opening the tank drain valve.

Right Next Door?

Where do you put the extra tank? Right next door to the existing compressor tank, or on the other side of the workshop?

For most DIY type applications it really doesn’t matter. Just remember that you need to have a hose or pipe long enough reach from one tank to the other.

How long to fill an air tank - image of air tank

An extra tank can be any shape or size, depending on the capacity of the compressor pump and motor. Image: www.compressorworld.com

Tank Draining

You will have to drain both air tanks regularly.

Make sure you have access to the drain valves on both tanks to make this convenient for you.

How To Install?

You can “hard plumb” the new tank, but the easiest way is to connect the two tanks with a hose.

Use the existing coupler on the current air tank. This coupler allows you to plug a connector into it, and once you plug in the connector air will flow into the air line or hose.

You’ll need a length of air hose long enough to reach from the coupler of the main tank, to the inlet connector on the second tank. This air hose will have a coupler on one end, and a connector on the other.

Don’t plug the connector into the coupler until you have the hose connected at the new tank end.

Fitting It Up

Thread a Tee into the intake port on the new tank.

Into one side of the Tee thread a coupler.

You will push the coupler from your extension air hose onto this connect, effectively connecting the two air tanks.

On the other side of the Tee, consider adding a nipple, an air filter, another nipple, and then another checked coupler.

Fills Both Air Tanks

Now, every time the compressor pressure switch calls for air, the compressor will start and run until it fills both air tanks to the high pressure cut out level.

Just as the connector on your compressor tank has a checked coupling to keep air in the tank when there isn’t a connector attached to it, the coupler you’ve added to the Tee on the new tank will keep the air in both tanks until you’re ready to insert an air line connector into it.

And, with the second tank, you have a lot more air to use for your tools, between compressor cycles.

Check Valve

Where the air enters the tank on the compressor, there is normally a check valve installed. This allows air into the tank, but won’t allow air back out that way.

This is important, which is why the secondary tank is installed after the primary. Then air from the both tanks cannot escape back up the supply line from the compressor when the compressor is stopped and the unloader valve open to atmosphere.

Duty Cycle

Now that you’ve got your second (or third, or fourth???) tank installed for your one compressor, it will run longer in order to bring the pressure in all of your tanks up to the high pressure cut out level.

Be aware of a little thing called duty cycle. It would be a shame to have your compressor work so hard and so long to fill up the multiple tanks that it burned itself out because you didn’t give it a chance to cool off often enough!