by Tom Gaylord
Writing as B.B. Pelletier

Umarex ReadyAir portable compressor

Part 1

This report covers:

  • Setting up the compressor
  • Setting the pressures
  • Test plug
  • Not set and forget
  • The tests
  • Test One — BSA R10
  • Bleed valve
  • Test two — AirForce tank
  • Runtime
  • Test 3 — AirForce tank outdoors
  • Summary

Today we look at how the Umarex ReadyAir portable compressor operates. I’ve devised three tests that should demonstrate the operation quite well. Let’s go.

Setting up the compressor

To get the compressor ready for the first two tests I attached the 110 volt household power cord and the flexible air hose that comes with a female Foster fitting on the end. If only all airgun manufacturers would use the male Foster fitting for all their guns the world would be abetter place!

The other end of the hose that attaches to the compressor is a properly sealed 1/8 BSP threaded adapter that has a rubber seal inside. I tightened it hand tight for all the tests and it held air perfectly.

Setting the pressures

The compressor comes with the control panel set to run in English, the pressure reading in PSI and temperature reading in Fahrenheit. The languages can be changed to French and Spanish with the push of a button. Pressure can read in bar and temperature in Celsius if you prefer.

Your first task after plugging in the compressor is to set the desired fill pressure. When the compressor gets to that pressure it will stop pumping, though if the cooling fan has come on it will continue running. You need to leave it running until the temperature drops below 87 degrees F. The fan never switches off until you push the off button.

Test plug

In the maintenance video that we watched in Part One, Rick Eutsler wondered whether there would be a test plug for the air hose in the compressors that are shipped to the public. There is one in the test compressor. It came to me plugged into the Foster fitting on the hose.

ReadyAir test plug
The ReadyAir does come with a test plug to check out the system before pumping an airgun.

Not set and forget

I told you in Part One that the ReadyAir is not a set-and-forget compressor, but I’m telling you again. However, because it operates so quickly, that really won’t be a problem for you. I had this one running in my office and could hear when it shut off. I kept an eye on the display, but that was more because I was curious than for any other reason. It’s a good thing I have to return this one to Umarex USA because if it was around my place I would never get to use my big Air Venturi compressor or my carbon fiber tanks.

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The tests

The first two tests are indoors, using house current, which in the U.S. is 60 Hz 110 volt current. I’m plugged into a 15 amp outlet. Before the first test I checked the compressor with the test plug installed in the end of the air hose. The plug seals the air hose, allowing pressure to build quickly. It’s a simple test that the whole system is running as it should. I set the test pressure at 4500 psi and started the compressor. It read 72 degrees when it started, with the house temp reading 69 degrees. It got to 4500 psi and shut off in under a minute and the temperature increased to 75 degrees.

Test One — BSA R10

My BSA R10 Mark II has a 200cc reservoir. That’s 12.2 cubic inches. The reservoir gauge read 110 bar/1595 psi when I started the test and the compressor was set to stop at 232 bar/3365 psi. When it is plugged into the wall the compressor’s display lights up. That’s when you make any adjustments and set the fill or cutoff pressure.

ReadyAir R10/product/umarex-readyair-portable-compressor?a=9732
The BSA R10 was the first to be filled.

When you are ready, push the start button and the compressor begins to pump. Don’t forget to close the bleed valve before starting the compressor.

Bleed valve

I love the handle on the ReadyAir bleed valve. It’s large and grippy and was obviously made by someone who understands what we are doing when we bleed the line.

ReadyAir bleed valve
The brass bleed valve (arrow) is closed when the compressor is pumping. The large grippy handle makes bleeding very easy.

On a carpeted floor the compressor jiggles back and forth about a quarter inch each way with the rhythm of the pump. 

The compressor’s starting temperature was 82 degrees F. When the pump stopped pumping at 3365 psi after 4 minutes, the temperature read 120 degrees F. The fan cooled the pump back down to 87 degrees F in another 5 minutes and then I shut it off.

That’s how it went. The ReadyAir was efficient and quick to fill the BSA. Like I already said, if I owned a little compressor like this one I doubt my big compressor would get much of a workout.

Test two — AirForce tank

Now we’re going to put the ReadyAir to a real test. I took an empty 495cc/30.21 cubic inch reservoir from an AirForce Escape and attached it to the compressor. I set the fill to 3,000 psi and started her up. This time I noticed something that I hadn’t seen with the smaller BSA reservoir that was 2/3 full. The pressure in the tank would rise and then sink back down by several psi. It did that throughout the entire fill.

The compressor started at 84 degrees when the air tank was empty and 17 minutes later when it stopped pumping at 3,000 psi, the temperature was 140 degrees F. I was so faithful to time the fill with my watch, but this time when I disconnected the air tank I noticed that the display on the compressor was also timing the fill. It said the same 17 minutes I had just recorded.


The manual has an explanation of everything on the display and now that I know what to look for I see a runtime indicator. I didn’t see it before, nor was I aware it was there. Not only does it tell you what the compressor has just done, if you keep a logbook for your compressor it gives you the amount of time to enter, so you’ll know when those 20 hours are up and the maintenance cycle (piston rebuild and charcoal filter replacement) is required.

ReadyAir runtime
The runtime is the yellow numbers in minutes to the left of the max fill pressure.

So, 17 minutes is a longer time. But I went from zero psi and you won’t do that very often. You’ll go from 2000 psi and fill to 3000 in a few minutes.

Test 3 — AirForce tank outdoors

Test three is a test using the 12-volt cables attached to a car battery. I first attached the battery cables to the compressor and then clamped them to my truck battery. The same AirForce tank was used and I had emptied it all the way before this test. The battery cables are very long and the pump can sit on the ground. The manual advises that you leave the vehicle running while the compressor is running.

ReadyAir truck
The battery cables are long enough that the compressor can sit on the ground.

Obviously this test was outside, and it was in 50 degree F weather. Umarex says to operate it in the shade if possible, to keep it cooler. The pump never got above 105 degrees F in the 18 minutes that it took to fill the tank and shut down. The temperature of the compressor dropped below 84 degrees within five minutes after the pump stopped but the fan kept running. I then pressed the on/off button and the pump started as the entire compressor shut off. It’s a strange sensation, but the pump stops right away when the off button is released.

This was a second test of filling from empty. Normally a tank this size will take 6-8 minutes to top off becauise you will never go below 2,000 psi.


What more can I tell you? The ReadyAir runs just like it should and the fill times are relatively brief. The instructions are straightforward and everything you need comes with the compressor.

I think the ReadyAir gives us a reliable and supported air compressor at an affordable price for many more airgunners.