What do you do when your air line pressure drops?
You’re spraying wood, plastic, metal, or whatever … then suddenly your pressure drops so badly your spray is inconsistent. Maybe the guy next to you mumbles a curse. That’s happened to you, right? Those air line pressure drops and dynamic air pressure readings (where the pressure bounces around) are important, especially when using the air-atomizing settings.
We have a few ideas on what to check.
Do you have the right hose size?
It’s typically a hose size problem. Those losses in pressure occur when there’s an insufficient hose size and quick disconnects are the main culprits.
One factor could be the amount of length and air line travel time. Air line pressure drop is affected by; length of travel, CFM, and air pressure at the source. The chart below illustrates the pressure drop in a 35 ft. hose at various CFM’s and output air pressure.
Pressure drop in 35′ rubber hose
(not including pressure drop from fittings & Q. D.)
| 6 cfm @ | 10 cfm @ | 15 cfm @ | ||||
| Hose I.D. | 125 psi | 30 psi | 125 psi | 30 psi | 125 psi | 30 psi |
| 1/4″ | 5 | 15.7 | 12 | N/A | 26.8 | N/A |
| 5/16″ | 1.6 | 4.9 | 3.7 | 11.5 | 8.9 | N/A |
We would recommend the more flexible 5/16” air hose up to 25’ when the spray gun requirements are about 10 CFM, and the 3/8” hose for spray gun requirements over 10 CFM and up to 35’.
To set the desired gun incoming pressure without having to pre-determine your actual pressure drop use this technique. Just pull back the gun trigger ¼” so as not to omit fluid, however air is exhausting. Then adjust the air regulator at the other end of the hose to the desired air pressure which we have labeled as dynamic air pressure.
Are your hoses worn?
Give a visual inspection to ensure there aren’t tears or kinks in the hose. Sometimes those can cause pressure drops and may be small enough that you don’t immediately notice.
Is there a problem with the connection?
Cracks in your gun, worn valves, and the like may prevent a good connection between your spray gun and hose, which can cause pressure problems. Visual inspection of your gun and the connectors should help clarify if that’s the case. If it is, we can help you replace those parts.
Is it a compressor problem?
For bigger shops, you may be using an air compressor to help spray projects. The compressor makes a big difference in getting that perfect spray. It could be several things, including needing maintenance. In South Carolina, Michigan, and Ohio, we have compressed air service technicians who can help. They work on all major compressor brands, including Kaeser, Ingersoll Rand, Gardner Denver, Quincy, Sullair, Chicago Pneumatic, and Atlas Copco.
And if you’re really stuck, the entire compressor shutting down and halting production, those locations offer 24/7 service, 365 days out of the year. They’re even working on Christmas.
Contact us!
Although we’re not there, we may have a few ideas and some products to replace compressors, valves, and hoses to ensure you’re spraying perfectly every time.
