What Is The Pressure Regulator For?

air compressor pressure regulator
(Last Updated On: September 19, 2020)

Whether you know it as the pressure adjustment valve, or as I and many others call it, the pressure regulator, why is there one on a compressor and what is the pressure regulator for?

You’ll spot the regulator. It is normally in the line on the air compressor through which tank air to flow from the compressor tank to the coupler into which connector on the air line is inserted. Once inserted into the coupler, the connector opens the coupler internal check, and air can flow into the air line.

The pressure regulator will look similar to the one shown on this page, though, on many smaller air compressors, the only part of the regulator that might be seen is the adjustment knob.

What Is The Pressure Regulator For?

When the compressor runs to fill the tank, once the tank is full, the compressor shuts off. Depending on the make of air compressor, the air in the tank might be at 125 PSI, maybe 150 PSI or even, on some compressors, 200 PSI.

There are very few air-using tools that require air at those pressures to work properly. In fact, by supplying too high an air pressure to the air tool, not only will it waste air, but it could also lead to early maintenance issues with the air tool.

Buy this air pressure regulator kit here.
The device that is used to REDUCE the tank pressure level to a pressure that is more suitable for the use is the pressure regulator.

The compressor pressure regulator allows the user to use the adjustment knob on the regulator to set a pressure level for air in the hose to the tool that is more in keeping with what that air tool requires to run properly.

If the air tool, for example, runs best at 90 PSI, then use the pressure regulator to turn the air in the air line down to 90 PSI from the higher pressure in the tank.

A compressor regulator that is working properly will maintain the air line pressure to the air tool at the set level, in this case, 90 PSI, as long as the air pressure in the tank is higher than the regulator set pressure.


What if the compressor tank air pressure is lower than the regulator pressure setting?

A misconception about compressor regulators is that they can, some how, increase pressure from the tank. That is false. A regulator can only reduce air pressure.

If the air tool begins running with 90 PSI pressure in the line, and with 150 PSI pressure in the tank, and that air tool uses more air than the compressor can supply, then the tank air pressure will drop.

At the start point of that compressor, the compressor will begin pumping more air into the tank. If, however, the demand is greater than the compressor pump can deliver, air pressure in the tank will continue to fall.

Once the tank pressure falls below the 90 PSI that the regulator is set for, then the pressure in the air line will fall too.

If the air tool continues to use more air than the compressor can deliver, the the tank air pressure and the air pressure to the air tool, could drop to zero.

If the air tool is stopped, then air in the compressor tank will rise to the normal stopping pressure, and even though once again the air in the tank may be at 150 PSI, the regulator will ensure that, once again, the air stream to the air tool through the regulator will be at the 90 PSI setting. Air will continue to flow through the air regulator to the air tool at the 90 PSI setting as long as the tank pressure stays above that 90 PSI setting.


Adjust the regulator often!

Compressed air is expensive to generate, and using it at a lower pressure means that the compressor does not have to run as often as if the pressure demand were higher. That reduced compressor cycling saves energy and reduces wear and tear on the compressor as well.

Get accustomed to lowering the air pressure, using the air regulator, to the best and lowest pressure suitable for the work to be performed.

And that answers the question “what is the regulator for”!

Check this regulator out; PneumaticPlus SAR400T-N04BG Compressed Air Pressure Regulator 1/2″ NPT with Gauge & Bracket (T-Handle)

Do you have a question about your air regulator? Perhaps someone can help. Why not ask for some regulator help by using the comment form below?

Hello, I am Bill, the Compressed-Air-Man. I have years of experience in industrial and residential compressed air applications, air compressors and general pneumatics. I created this site to help professionals, students, and DIYers understand and properly implement and maintain compress3ed air systems.


  1. I have a craftsman model 283150571 compressor/ paint sprayer and need part ;# 633820, pressure adjuster. Also owners / parts manual.
    Any help will be appreciated.

    • Bob, since you have asked about the Craftsman pressure adjuster, and since I perceive that to be the regulator, I’ve moved your question to the regulator information page.

      I was unable to find any information about your compressor / sprayer at all, so I can not tell what kind of regulator yours is. Assuming it’s anything like the one shown on this page, then simply find a non-OEM replacement that has the same hole sizes for the air line fittings, the gauge, and guy any brand that has the same range of pressure – or close to the same range – as the original.

      If I’ve got it wrong, please add a comment and a photo of the one you are looking for, and perhaps someone can help find the product and the manual for you too.


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