Only a Short Burst of Air?

You squeeze the trigger on your blow gun, you get only a short burst of air, and then the air flow dribbles down to almost nothing. What’s wrong with the compressor?

To understand that, we want to discuss the flow path of the compressed air from the tank.

The schematic below takes the convoluted (possibly) flow path of the compressed air on your air compressor, and turns it into a straight line for easier understanding.

In this compressed air flow graphic, the compressed air flows in a left-to-right direction. Air flows from the tank, through the regulator and to the discharge air coupler.

air-path-from-tank

Air typically cannot flow past the discharge coupling until there is a connector inserted. Inserting the connector opens the check ball inside most “checked” air couplings and  allows air to flow through it. That is why all the air in your compressor tank doesn’t flow out the coupling all by itself.

Let us assume that farther to the right, at the end of the connector and air hose you have a blow gun installed. You pull the trigger, and you get only a short burst of air. Here may be why.

Compressor Tank to Regulator

In the drawing there is nothing shown in the pipe between the compressor tank and the compressed air regulator most smaller air compressors come equipped with. The absence of another component in the line from the tank to the regulator is typical, and it is then reasonable to assume that if you have air in the tank, you will have compressed air flowing to the regulator.

Is there air in the compressor tank?

Of course, if there is no air in the tank, you will not get air flow to the regulator. Your compressor typically will come equipped with two air gauges. One will display the tank pressure, and the other, again typically installed on the regulator, will show the regulated pressure.

So, identify the tank gauge and read the pressure. If the tank is full, that gauge should read 100-150 PSI on a smaller air compressor.

Regulator gauge reading

compressed air gaugeAssuming that there is lots of air in the tank, the next thing you want to check is the reading on the regulator gauge.

The gauge in the photo is typical of gauges seen on smaller compressors. This one has a bottom mount. Yours may be a back mounted gauge, or it might be a panel mount gauge. If a panel mount, typically it will have a label identifying it as the regulator gauge.

Note the pressure on the gauge.

Whatever the reading is on your regulator gauge, that is the pressure that will flow downstream to your air tool. If this reading is low, lower even than the 50 PSI seen on the air gauge in the photo, that may be a reason why your air tool runs with only a short burst of air. If this setting is too low, then there will not be enough air to run the tool.

If your tank gauge indicates a pressure of 100 + PSI, turn your regulator knob to increase the setting on the gauge to, say, 90 PSI. Run the air tool. Did this solve the problem? If not, you have eliminated one potential roadblock of the compressed air flow from the tank to your air tool.

Is it the compressed air regulator causing only a short burst of air?

If you dialed the pressure setting on the regulator up and down by turning the adjusting knob, and the pressure reading on the regulator gauge changed up and down as you rotated the knob, then the odds of the problem being the regulator are lessened.

Since checking the regulator will involve a bit of plumbing changes on your air compressor, let’s leave the air regulator for a second, as long as the pressure display on the regulator gauge moves up and down with the turning of the adjusting knob. We’ll come back to this area if need be.

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Here is where we continue discussing resolving the air compressor problem of only a short burst of air coming out of the air hose.

 

Comments

  1. so after reading your article and doing my own trouble shooting i think it is the discharge coupling. Here is why, if i push the the hose connector harder into the coupling, i hear air go past the coupling into the hose, i get a short shot of air, as in whats charged in the hose, and hten it dies off. I pushed the connector harder into the coupling again, and again, i hear air pass, and the hose fills up..

    Based off of this, should i replace the coupling, and are the simple to replace??
    Thanks for your article and diagram, it really helped.

    • Glad it helped. As noted in the couplers and connectors section, all are NOT interchangeable. It sounds to us as though you have a coupler to connector mis-match. Find a coupler and connector that works, and use that make and model on all your air connection needs and discard the ones that are mismatched. Replacing them is easy. Empty all air from the tank, remove the existing discharge coupler with a wrench, and replace it with a coupler for which you have the right connector. Or, find the right connector for that coupler, one that allows free air flow when it is inserted, and use that connector on all your air tools, air lines, etc.

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