About Compressor Regulators

There is quite often a misconception about compressor regulators that we will try to dispel here, as well as giving you lots of information about how to best use your compressed air regulator.

While probably not all, most air compressors that have a tank will come equipped with an air regulator. It is typically located on the discharge line from the tank, upstream from the discharge coupler, which is the coupler into which you plug the connector on your air hose. Depending on the make and model of your air compressor, your compressor regulator will look something like the one in the image.

Fix My Compressor - About Compressed Air RegulatorsYour compressor regulator may be a different color. Your regulator may be bigger or smaller,  it may have a smaller or larger air gauge or the air gauge may not even be directly attached to the regulator, your regulator adjustment knob may look different, yet all air regulators are basically similar in function to the one shown.

Using Compressor Regulators

Using the regulator is pretty straightforward. If you turn the regulator adjustment knob in a clockwise direction, that normally elevates the regulator pressure setting. Turn the knob counter-clockwise and the regulator setting is reduced.

Whatever pressure is displayed on the regulator gauge – not the tank gauge since your compressor typically has two gauges – is the pressure of the air stream exiting the discharge coupler into your air hose.

Some regulator adjustment knobs lock by either depressing them or pulling them out. If you find that you cannot turn the regulator adjustment knob, try pushing down on it or pulling it up. If it has a built-in adjustment lock, that should unlock it.

About Compressor Regulators Misconception

The most significant misconception about compressor regulators is that they can raise the air pressure!

If your tank pressure is 100 PSI for example, you can increase the discharge pressure by turning the knob in a clockwise direction. If you try to dial the pressure up past the tank pressure of 100 PSI the regulator gauge needle will stop at and display the tank pressure of 100 PSI, and that’s the pressure that will be exiting the discharge coupler to the air hose.

The air regulator can only adjust pressure down. No air regulator can adjust the pressure up past whatever the pressure is in the tank or air mains.

What Good Are Regulators Then?

The compressed air regulator is an important device. Why? Because it allows you to dial the pressure down to the the absolute minimum required by the air tool you are trying to operate.

Running your air tool at the minimum operating pressure extends the life of the air tool, reduces the amount of air used – which cuts down on energy cost to compress the air – and reduces the cycle frequency of the air compressor, which has positive ramifications for the compressor life and maintenance cycle.

Always adjust the air regulator pressure setting to the minimum pressure level required to operate any of your air tools.

Can You Have Multiple Air Regulators?

Absolutely you can. Many industrial plants plumb their compressed air up to a ceiling mounted air main that circulates the plant. The air pressure in the air main is typically the highest pressure that the plant compressor can generate.

Drop lines are installed from the air main down to the shop floor to supply compressed air to various pieces of equipment. Each machine or piece of equipment may have a different minimum operating pressure, so there will be a regulator (and typically a filter too) installed just before each piece of equipment so that the pressure can be set to the optimal performance level.

So too, in your home shop you can adjust the pressure for your air line on the regulator in the discharge line from the tank, and if desired, you can install air regulators anywhere else in the line to be able to further adjust the air pressure if you have multiple uses of compressed air.

Compressor Regulator Maintenance

For most of us DIY type folks with home or small shop air compressors, the regulator that came with the compressor will be a cheap one, mass produced in some foreign land for pennies each, and sold to the compressor assemblers for not much more than that, we expect.

The diaphragm inside the regulator upon which the compressed air presses to control the downstream pressure will crack in time, through high cycle exposure, from contamination of the diaphragm by compressor oils, debris in the air stream, or drying out of the regulator diaphragm over long periods of inactivity. If the regulator diaphragm cracks, your regulator will leak all the time.

The regulator gauge is cheap as well, and over time the innards corrode, or an impact might shatter the gauge-face cover.

Industrial air compressor regulators typically have a good supply chain of spare parts. They are expensive enough to warrant dismantling and repairing rather than tossing them out.

The typical DIY compressor air regulator does not enjoy a good supply of parts. With the price of a new regulator being in the $20 – $30 range, it’s hard to justify buying a kit (if you can find one) for almost that amount of money and spending a couple of hours tearing the regulator down and trying to get it working again.

In other words, the low end regulators are basically disposable when they fail.

You can  replace the gauge on a regulator for around $7 – $10, however. If it’s the gauge that goes, do get a replacement.

If the regulator starts to leak, sure, try to find a diaphragm for it and fix it if you can. For us, it’ll be time for a new compressor regulator at that point.

Since most replacement regulators come equipped with a display gauge, if the old gauge is still working, keep it for a spare.

Got a question about your air compressor regulator? Use the comment form below to ask it, and we’ll help if we can. If you see a question about air regulators here, add your comment if you can help. Only questions and comments about compressor regulators will be approved for this page.


  1. Ray Boylan says:

    I have a Campbell Hausfeld WL802600AJ, 155PSI, 29 gal tank. The Regulator and both gauges and outlet valve receivers are ll one unit. When I turn my regulator knob counter clock wise (lower), the pressure releases from both the tool outlet and the tank gauges. I cannot remove the regulator and turn it around to face the outlet valves, it does not come apart. Do I need to buy an entire new unit?

    Additionally, the regulator comes attached to a manifold. It is part # WL024502AV or WL022500AV. I will try to add a PIC. All regulator knob settings, adjusts both gauges to the same pressure level. It sets the Tool valve pressure quickly, then continues to bleed air from the tank, the air comes from under the regulator knob.

    / Ray

    • I’ve put your two posts together. Thanks for the added info. It does sound as though the regulator diaphragm has cracked, or a seal has let go, Ray. If you search for parts for your compressor, you will see the much of what is attached to the “manifold” can be removed. You can, then, make the base manifold from brass parts from a good plumbing wholesaler, and add the removed parts to that. You can add a new regulator then, and they aren’t too expensive. If you want to keep it simple, and you can find one, yup, you can replace the whole manifold too.

  2. Hi,

    I am pretty new to the world of air compressors and I am trying to better understand how I can utilize air regulators. Here is my question. I have a very large towable air compressor that produces around 185CFM at 100 psi. I have a dessicant air dryer that has a three stage filter that is connected inline between the tool and the compressor. This dryer is rated at 142PSI and about 40CFM airflow. My tool requires at least 30 cfm at 100psi. My questions is whether or not an air regulator installed between the air compressor and the dessicant air dryer would allow me to safely use the air dryer with this large air compressor. Do air regulators allow you to use tools and filters that are rated way lower than the compressor in terms of PSI and CFM? I hope I am making sense. I have heard of tools and filters exploding from too much pressure. Thank you

    • Sorry John. I’m not getting it. Your compressor is putting out 100 PSI, yes? Your desiccant dryer is rated for 142 PSI. The air tool needs 100 PSI. So what is the problem? Is it that the 185 CFM coming out of the compressor will overwhelm the dryer? That being the case, you’ll want to put a manual valve (not a regulator, but a valve) to be able to reduce the flow to the level necessary. The regulator is there to adjust the downstream pressure, the valve is there to adjust the flow, even though, in some cases, the regulator does both, it wouldn’t in my opinion in this case. You’ll need some way to measure the flow, or just take post luck, and see if cutting the flow in half, for example, allows enough drying of the air that the air tool isn’t encumbered.

  3. Hello All,

    I have an Ingersoll and Rand water trap regulator. It has been working well for 8 months until today. The regulator still does it job at lower psi’s, but once I try to spray at higher pressures, it shoots straight to 150psi and stays there. I don’t want to buy a new one as they run around $100, any ideas about how dire this problem is and what I could do to fix it?

    • By water trap regulator, I take that to mean that it is a combination filter/regulator?

      If 150 PSI is the upper pressure output of your compressor, then I would suspect either the spring in the regulator is going and / or the diaphragm is failing too. The flow capacity and port size will be the deciding factors in replacing it, AJ, though some of these better quality regulators do have repair kits that cost less than a replacement regulator. If you google repair kit for XX (port size) IR regulator, you may find sources.

  4. kurt brees says:

    I bought a used DeVilbiss Pro Air 2, model # 430-1 , max pressure 125. When I turned it on the first time, it built up pressure to about 125 and air started coming out of the small relief hole below the pressure line on the regulator.

    I was able to find a new regulator and installed it. Same thing. It built up pressure until about 125 and air started coming out of the small relief hole at the base of the metal pressure line attached to the regulator. It will continue to bleed off until the tank is empty unless it is turned on again. It holds the pressure will running but not while not running.

    Any ideas what is happening? Thanks, Kurt

    • Hi Kurt. My guess is that you’ve got a leaking tank check valve. Perhaps you might remove it, clean the seats, and replace it and then check and see if the problem persists? Make sure you’ve dumped all the air before disassembling the fitting on the tank. Let me know how it turns out would you?

  5. hi everyone my question is i set my compressor outlet @2.5bar but when it compress down to 2 bar when it use from tank it rise to the previous so how can i fix it

    • A bit more clarification please. If the regulator is set for 2.5 bar, that’s the pressure that the air tool will see, as long as the air pressure in the tank stays above 2.5 bar. If the tank pressure falls below 2.5 bar, the regulator can no longer maintain the downstream pressure. That would suggest to me that whatever you are using air for is pulling more air than the compressor can generate. Is this what is happening?

  6. I have an air compressor that I just purchased. When I decrease the air pressure the regulator leaks until the pressure of the entire tank matches the setting on the regulator. Any idea what is wrong?

    • It sounds as though the regulator is installed backwards. By that we mean that the arrow on the regulator is pointing towards the tank, and not towards the discharge coupler. Try – with the tank empty and the power cord pulled from the socket – removing the regulator and reversing the flow. Let us know if this helps, will you?

    • Jack Schnabel says:

      It’s working correctly. It’s just bleeding off the pressure in out going side of the line.

      • Okay. So you say the regulator is “working correctly”? Nope, not if it’s bleeding air. Did you determine if the arrow on the regulator is pointing to the discharge coupler or towards the tank?

  7. Hi,
    I have an Iwata Smart Jet Pro that has developed a problem. I was unable suddenly to turn the pressure regulator knob. At the same time the pressure gauge stopped working, not budging from zero despite the compressor blasting air to my airbrush. I assumed that the problem stemmed from the pressure knob. I took advice and removed the knob cap and loosened off the nut. I can now move the knob again, however the dial still does not adjust the pressure and the gauge still does not move. My airbrush blasts air, but I have no control over the amount. Any advice on how to solve this will be gratefully received,

    • Short of tearing down the existing regulator, trying to determine what part(s) has failed, trying to find the part(s) and then reassembling, replacing the whole regulator would be the choice as far as we’re concerned. These regulators are not expensive. Just make sure when you install the new one that you point the arrow on the body of the regulator towards the discharge coupler – the coupler into which you plug your air line.

  8. My air regulator knob is very hard to turn. Is there a lubricant that should be used? It’s not leaking.

    • No lubricate that we know of. If pushing or pulling on the regulator knob provides no benefit, we can only assume that some air borne debris has created a friction issue inside and it may be time to replace the regulator.

  9. Hi Willyr,

    first off, thank you for this site and the wealth of information shared! i’m a compressor newb and learning along the way. Anyway, my question is with regards to my old sears/craftsman compressor (model 919.717521 2hp) from 1980 (bought from the original owner and it’s in beautiful shape!). I think there’s a leak somewhere in the regulator. I’ve tried googling for parts kits and ended up talking to a bunch of compressor repair guys who keep referring me to someone else!

    anyway, can i still rebuild this regulator or should i just try and get an aftermarket one to try and fit in? will there be any issues with that? with the compressor off, there are no leaks, it only hisses/leaks when i spin the regulator on and it sounds like it’s coming from around the regulator itself. i’ve heard cracked diaphragm from the same guys above. just wanting to confirm this diagnosis first and your thoughts on the fix.

    ‘preciate any tips/advice! (hope pics work)

    • just to add, i’m looking at part 69/70. guess i can take a real pic with the cover off. also would like to the new parts (if needed) to at least fit as closely as it can through the 3 holes in the plastic cover (or am I asking too much?! )

      one of the techs i spoke to even suggested skipping or plugging the regulator and just running straight off the tank. but i’m thinking that’s probably not a good idea (wasting air, and running too high PSI through the tools/recommendations and wearing them out)

      i got this compressor for a song and would hate to see it go to waste. i also forgot to add that i’m still about to run a 220 V outlet in the garage to run this baby. it’s been sitting there for a couple years so plan is to drain tank of water and to change the oil and give her a good clean. cheers.

    • Okay, the image came through fine Romney, and we see the regulator. We expect that you will have a hard time finding parts for this regulator, though the people to ask about this for sure are at Sears service. Assuming you cannot, we expect with some manipulation a general purpose, panel mount regulator can be fitted into the hole in the cover, and plumb into the discharge line from the tank. Take the old regulator to the big box store if you cannot find an OEM regulator, and try to find one that is similar in panel mount size. Don’t worry about the plumbing, in as much as straight and elbow fittings which are readily available can be used to plumb the regulator into the line. It, however, may not maintain the dignity of “the old girl” but it should come close. As to the leak, the regulator should vent while you are dialing the pressure down if you have an air hose attached to the discharge coupler. It should not normally leak when you are dialing the pressure up, so we concur, that if that’s what is happening, it’s most likely a cracked diaphragm.

      • Thanks for the speedy reply WillyR! very much appreciated! Yes, definitely leaking when dialing up. looks like it’s a one piece unit with the tank pressure gauge off the manifold so i’m guessing i’ll be needing to replace both with some dual unit and or separate units with like you said, figuring out the best fit with some plumbing. guess i can even live without the plastic console cover on worse comes to worse

        piece 74 is a pipe plug on the manifold so i’m guessing that’s a possible option for relocating a certain aftermarket piece where i just use that outlet and plug the old location for the regulator?

        will see what i can find at Sears too but i’m guessing it’ll be an aftermarket/modded piece which is a-okay!

  10. Loni Wulff says:

    Hi, I just installed a Kobalt 3/8 in regulator on my twin tank Central Pneumatic wheelbarrow compressor. I bought it used and when I ran it it would pop off at 150 tank pressure. This regulator continuously bleeds off pressure and won’t let me get any higher than 60 psi and tank pressure can’t build any higher than 70; did I just install a broken piece of junk?

    • Loni, we’re a bit confused. You speak of the Kobalt regulator, and then refer to it popping off at 150 PSI. The regulator does not “pop off”. Are you, perhaps, referring to the PRV?

      If you are referring to the regulator, please confirm that you have installed it with the arrow on the regulator body pointing towards the discharge coupler, and NOT towards the tank. If it is pointing to the tank, remove the regulator and install it with the correct flow path. That should stop the leak.

    • I’m having the same issues with the cobalt regulator, it continually bleeds ( seems to be out of the handle)

  11. I have a mini air compressor are the air tank pressure and the air regulator suppose to read the same . My tank reads over 200 in the red the regulator shuts off at around 100

    • We are a bit confused by your question. The regulator does not shut anything off. It is adjusted by a knob to set the downstream air pressure at the level you want for your air tools. If the regulator is set for 100 PSI for example, and the tank has 150 PSI in it, then the downstream air tools will get a steady stream of air at the 100 PSI you have selected on the regulator dial.

      If the air compressor is running tank pressure up to 200 PSI, and the normal cut out point of the compressors is, for example, 150 PSI, then it’s pretty certain that your pressure switch has failed, and we would recommend that you do not use the compressor again until that is repaired.

  12. Howdy, I have an old Emglo MK5HGA-8P compressor and the regulator screw broke. It is an old enough unit that I can’t find parts anywhere for it. The regulator screws into a manifold and comes apart easily, do you know of anywhere to get parts or do you know of a screw in replacement that will go in the manifold?

    • Indeed, it seems that the regulator repair kit for this wheelbarrow compressor is no longer available. The further issue is, we do not have access to the compressor to unscrew the regulator to see how we could effect a replacement. We would not expect that the regulator is too unusual, and you may be able to install a replacement. The first thing to do is to remove the control panel cover and get a look at the regulator plumbing. We would expect it to be a normal regulator, and if so, any comparably sized regulator should work. If you wish, please start a new thread in this forum and add some closeup photos of the regulator area with the panel cover removed. Let’s see what’s under there.

  13. Chris Larson says:

    Aloha. I have an old military compressor, probably 80 gallons or so. It’s set to shut off at 147psi and turn back on at about 117psi. The tank has its own gauge, the regulator has a gauge and I put one after the regulator before the tool’s hose. I drained all the air out of the compressor and the hose end, unscrewed the pressure set knob all the way to the stop and filled the compressor tank. All three gauges read 147psi. Shouldn’t the out pressure be much lower than the tank with the pressure set knob backed off all the way? I’m thinking I bought a faulty regulator. I’m not hearing any air leak from the regulator.

    (UPDATE: Disregard the question. I took it apart and found that the adjustment screw was stripped.)

    Chris, we’ve included both your question and upates as your findings will, we are sure, help others with a similar regulator problem.

  14. So I’m not much a DIY’er, but a couple Christmases ago my father-in-law bought me a Porter Cable 150 psi air compressor. Embarrassingly I just tried to use it for the first time today to air up a low tire on my car. I followed the instructions about attaching the tube and proper fitting, turned the regulator pressure knob fully counter-clockwise and turned it on. When the tank air pressure reached about 140 psi it shut off and I turned the regulator knob clockwise and was going to set the regulator pressure to about 100 psi. As I turned the regulator knob the tank pressure decreased and the motor started running again, before the pressure in the regulator reached even 20 psi. That’s not normal, is it? Any help is appreciated.

    • Please shut the regulator off, run the compressor until the tan pressure reaches the cut out setting and the compressor stops, then dial the regulator back up. Monitor the TANK air gauge. How fast is it dropping?

      In order for the compressor to start, assuming the pressure switch is working properly, the tank pressure must drop to below the cut in pressure setting of the pressure switch.

      If the tank pressure is dropping while you are dialing up the regulator, and if your regulator is installed correctly, then typically the only place the air can escape is out the regulator relief hole. If that is happening, it is the regulator at fault and a repair or replacement is in order.

  15. I have a ABAC Pole Position Compressor 2HP / 24Lt – It is just a cheap model and fairly old.
    My question is regarding the Pressure gauge and regulator – this seams to be 1 unit on my item and only has 1 gauge which shows the pressure of the tank, The regulator only has numbers round a twist knob however it has come loose and so the numbers do not match the reality i.e. when on number 3 air is only just escaping.
    Do you have any ideas how to fix this? Can I repair it, if so how will I know if the pressure is correct.
    Another option will be to replace the regulator – any help identifying the right one would be helpful.

    • We tried to find an image of the compressor to better understand the problem. No luck, we’re afraid. Simply put, air from the compressor tank flows to the base of the pressure switch so that it can “read” the tank pressure and turn the compressor on an off as needed. That plumbing typically has the tank air gauge installed as well, so the compressor user can monitor the air pressure in the tank. The air then flows typically to a regulator that has its own gauge. The regulator gauge displays the pressure setting the downstream air tool or air-using application will receive. We would suggest that you install a tee upstream from the regulator and install a gauge there. Replace the regulator on your compressor will a general purpose mini-regulator, that will come with a gauge, and then plumb your compressors discharge coupling into the downstream side of the regulator. That should solve your problem.

      • Hi thanks for the reply I think it makes sense. To help here is picture of the offending item.

        ABAC Pole Position compressor regulator

        • After much searching found this which is the actual part.

          I think it is time to replace 🙂

          • Yes, it’s easier to acquire the exact same item. Yet you can also acquire a regulator like this, Karl, which will do the same job and you see the pressure setting on the gauge which might be easier.
            General purpose mini-air regulator

  16. Chad Murrow says:

    I have a Craftsman air compressor model number 919.167280. It has pressure regulator D27253. The nut on the inside of the regulator has stripped out and now the regulator won’t keep pressure. Does anyone know of a place to get a replacement nut for the regulator. I know they are most likely disposable, but a new regulator is around $60 and I can’t bring myself to pay that when all I need is a $.05 nut. Any help would be appreciated. Thanks.

    • Craftsman air compressor model 919.167280
      Chad, when we look at the image of your model of Craftsman air compressor, it seems clear that what your compressor needs is a low cost regulator, to replace your damaged one, since parts for mini regulators are almost impossible to find. The replacement air regulator need not be an OEM regulator which, you say, will cost $60. If you Google mini air regulator, you will find many sources for one that suits your compressor, and they cost $15-$20.

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