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Pressure drop while spraying with HVLP spray gun

Published Categorized as Air Compressor Troubleshooting, Air Tools 5 Comments on Pressure drop while spraying with HVLP spray gun

Robert Matthews

I am running a Craftsman Single Cylinder Oil Free 6hp 30 gal compressor (8.6 scfm at 40 psi 6.4 scfm at 90 psi.)

My gun is rated at 9 scfm at 35 psi, 12 cfm at 43 psi. I have used this set up for over a year with no problems.

In the middle of spraying the other day the pressure of my gun started to drop while i was spraying. I released the trigger.

When I pulled it again the pressure was there but only for a sec or two. Then it would drop to almost nothing and paint would barely come out of the gun.

Every time I released the trigger for a few seconds and then pulled it again the same would happen. I hooked another gun up and the same.

My blow nozzle does the same but not as drastically.

Why is this happening?

Robert, it seems that something is blocking the orderly flow of compressed air to your HVLP paint gun.

I suspect that your regulator is failing.

Typical air regulator - this one installed with the adjusting knob on the side
Typical air regulator – this one installed with the adjusting knob on the side. The regulator will work in any orientation.

That, or, the ability of the compressor to maintain flow has been compromised… something else is blocking the air, but I still think it’s the compressor regulator failing.

You may have a regulator problem, but since I don’t know what else you have in the discharge manifold of your compressor, that’s only a guess.

I would remove the regulator from the circuit and see if that made any difference to the flow to the gun. If you have another regulator, replace the existing one as a test, perhaps?

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By Bill Wade

About Air Compressors has been helping folks with their Air Compressor Problems since 2002 online. We're a community of DIY and Compressed Air professionals who are keen to support everyone across the globe with their air compressor issues and troubleshooting. Whether you're trying to identify an old air compressor, or troubleshoot an error code on a sophisticated new industrial air compressor - the community at About-Air-Compressors.com is here to help you

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