Here is a bit of info about your air compressor gauges

23
air compressor air gauges
(Last Updated On: September 19, 2020)

How to replace an air gauge, you say? Well the nature of the compressor air gauge that  likely comes along with a low-cost DIY type air compressor,  and they are just that…low cost. Both the compressor and the air gauge… cheap!

This means that the gauges are not built to handle heavy, prolonged use which might break a gauge needle,  and they will fail due to internal corrosion or mechanical fatigue. That might take months or years, depending on the use and the condition of the compressed air the gauge is monitoring.

Further, for many of us, our air compressors are relegated to the basement or workshop where things pile on them, other things run into them, and ultimately the gauge face gets cracked or the entire gauge might get broken off.

Time to replace your air gauge? It is pretty easy. Here is how.

There Are Two

First, know that most DIY type air compressors come with two gauges. One of the gauges is to give you a reading of the air pressure in the compressor air tank.

The other gauge is normally found as part of the regulator assembly on the discharge line from the tank to the outlet coupling. This gauge is to show you the pressure setting on the regulator, and shows the air pressure for your downstream application.

 

Air Gauge Configurations

Compressed air pressure gauge - understanding-air-compressors.com
Typical air pressure gauge. Photo: Northern Tool

As depicted in the photo the air gauge has a face on which the pressure range for that gauge is visible. That scale is protected by a carbonate or glass face, which is susceptible to breakage.

The diameter of the standard air gauge face is 1 1/2”. Another air gauge standard diameter is 2”. Yours is likely one or the other, and I would lean to the 1 1/2″ size as being typical, as it costs the manufacturer less money to install a smaller gauge on an air compressor.

The gauge will be equipped with a male thread fitting on the bottom or the center of the back. It does not matter to the gauge whether it is turned into  the air line from a male thread on the bottom of the gauge, or a back located male thread.

The different locations of the mounting threads are purely for the convenience of the installer or the location of the air line into which the gauge is threaded.

You can also purchase air gauges that are panel mounted to facilitate an industrial type installation. A panel mount gauge typically has a back mount, and comes with a space ring that allows the gauge to fit into a through hole on the panel, without dropping completely  through. An installer may have to run an air line to the back of the panel mounted air gauge.

 

Air Gauge Pressure Ranges

The typical DIY type compressor air gauge will have a pressure range of 0-160, maybe 0 to180 or even 0-200 PSI.

Air Gauge Pressure Ranges

As long as the air gauge you obtain as a replacement shows the normal cut in pressure level of your compressor, and the normal cut out pressure level, that it is a 180 PSI versus a 200 PSI really makes no difference.

Specialty application gauges will have different pressure scales on them, depending on the application for that gauge.

 

How To Buy Compressor Gauges

If your old gauge is in good shape  (or even if it is not) take it with you to the shop so that you can match-the-hatch and get the same size fitting, same sized face, and same pressure range.

If your new gauge is a back mount type, and your existing gauge has the fitting on the bottom, the new gauge may not fit. It is always good to get the same size and style if at all possible.

If your air gauge is totally gone, opt for a 1 1/2” face, 0-200 PSI pressure range, with a 1/4” male NPT fitting on the bottom. That is a pretty good fit for many DIY type air compressors.

 

How Much Are Compressor Gauges?

The new gauge will set you back somewhere between $5-$15 or so, depending on where you buy it.

If the gauge is priced more than that, it is possible you are buying:

  • a) an overpriced air gauge
  • b) a much better quality air gauge than needed
  • c) a specialty gauge of some sort
  • d) a different compressed air component entirely 🙂

How To Setup A Guage On A Compressor?

Make sure you unplug your compressor and open the drain valve in the tank to empty the air pressure completely. Else, when your air gauge gets down to the last thread, one final turn will shoot that sucker right up and out of your hands, as the air pressure in your tank blasts to atmosphere. Be careful!

Some gauges have wrench flats to use a wrench, some rely on you turning the body of the gauge to unscrew the thread. If the gauge is not broken before you do this, it quite likely will be after you do so!

compressor gauge

Anyway, unscrew the old gauge after you double check that there is no air in the compressor tank.

Use pipe dope or teflon tape (better the former than the latter as far as I am concerned) to coat the threads on the new gauge.

Turn the new gauge into the compressor boss until snugly-hand tight, and then turn if just further enough to orient the air gauge face to where you can best see it.

No need to over-tighten, as the pipe dope will seal the threads if they are screwed in just past hand tight and if you tighten too much, the gauge may break.

Plug in your compressor (after you have closed the tank drain valve) and away you go. You might want to put some soapy water around where the gauge threads go into the compressor just to satisfy you that the gauge fitting is not leaking.

Which Air Compressor Guage Should I Buy?

Out of different pressure gauges which one can be used on my air compressor?

A visit to the big box store or hardware store may reveal a host of pressure gauges, or not, depending on the store. Which one(s) then are the right air gauges for the typical do it yourself home or small workshop air compressor?

It is necessary to actually look at the face of the gauge you are considering buying, looking at whether the threaded part comes out the bottom or the back, and the size of the male thread fitting on the gauge.

Wika air gauge - what air gauge and I use on my air compressor?
Photo: www.wika.ca/

It doesn’t typically matter if the gauge is a 1  1/2″ diameter face, a 2″ face diameter or a different size gauge face entirely, yet buying the replacement gauge that is the same size as the one that you are replacing on your air compressor helps ensure that it will fit in the same space on that compressor.

Some gauges are used to display vacuum. Some are built to display extremely low pressure, or a limited pressure range. Some are liquid filled. Some are made with stainless steel parts which has an impact on cost.

It is important to consider your compressor air gauge specifics when heading for the shop to buy a replacement air gauge. One day you may have to for if you have your air compressor long enough, yes, the air gauges do wear / rust out.

Here are the things you want to look for when selecting a replacement air pressure, or air regulator pressure gauge for your air compressor.

  • same size gauge face ( if possible, not critical if a larger / smaller air gauge face will fit the space on your compressor)
  • same (or close) pressure range displayed on the gauge face (close means within 10 PSI of the range of the existing gauge)
  • same size mounting thread or style (as in a male as opposed to a female thread, and the same NPT or Metric thread size)
  • same mounting position of the threaded fitting (whether the threaded part comes out the back or the bottom of the air gauge)

For a DIY type home air compressor, another indication that you have selected the right gauge will be the price. Expect to pay under $15 for a typical air pressure gauge for use in a general purpose, low cost air compressor. You can spend more if you wish. For example, buy a stainless steel gauge versus a cheaper “just metal” one. It will still work just fine all of the other issues noted above are the same, you’ll just spend a whole lot more for a stainless steel versus a basic gauge.

The same for buying a liquid filled gauge versus a basic gauge. The liquid filled gauge will work just fine, but cost a gazillion dollars more (comparatively speaking) than the basic gauge… and both will work.

Replacement compressor air gauges are available at most decent hardware stores, bit box stores, on line, and certainly should be available in the air parts section of the store from which you purchased your air compressor originally.

 

What Happens If My Air Gauge Fails?

When I’m using my at-home compressor, doing an odd job around the house, the needle in the air gauge may move a few hundred times a day as the air pressure fluctuates through compressed air use and the compressor cycling. This is low cycle rate for an air gauge.

Compare that to the air gauge on a system, perhaps containing dozens of air cylinders or air tools, all cycling at a high rate of speed 24/7/365. The mechanical components in the air gauge may cycle hundreds of thousands of times a day.

broken air compresssor gauge

Eventually, mechanical fatigue will cause the moving parts of the gauge to fail.

You can lengthen the functioning life of an air gauge in high speed circuits by using a liquid filled gauge.  Normally filled with glycerine, the viscosity(liquid thickness) of the filling tends to slow by a small degree the speed with which the gauge’s internal mechanical parts  and the needle moves with air changes, reducing mechanical wear and impact damage as the internal parts of the gauge return to zero when the air is repeatedly exhausted.

If you have an application where compressed air gauge failure occurs, consider using a liquid filled unit to extend the life of your compressed air gauge.

 

I Don’t Have Enough Air Pressure

I don’t have enough air pressure, a visitor recently stated, and then asked how to turn up the cut out settings on their air compressor pressure switch.

The idea was that a higher pressure coming out of the compressor could, somehow, give more air flow.

Compressed air pressure gauge
Typical air pressure gauge. Photo: Northern Tool

Sorry. That’s not going to happen.

First off, the engineers that designed the air compressor designed in an upper pressure limit. That’s the high pressure setting that the compressor can produce, somewhere, typically in the 120-150 PSI range, though there are more industrially oriented air compressors that can generate more pressure than that.

Trying to turn up the pressure on the pressure switch so that the air compressor can build greater pressure than it was designed to will only mean that there may be an unsafe condition created – possibly too much pressure for the compressor components – or that turning the air pressure up past design limits will ensure that the air compressor will fail much sooner than it should.

If your air regulator is turned to the lowest air pressure at which the air tool works satisfactorily and in using the air tool at that pressure setting you keep running out of air, the problem is not one of pressure.  If your  air tool dies due to air starvation or you have to keep waiting for the air compressor to catch up – meaning it’s probably running all the time – then your air compressor is too small for the air demand of the tool(s) you are using. Period!

Adding a secondary tank will give you more run time for your air tool, but that will mean that the air compressor will run longer to try and fill two tanks, meaning you’ll wait twice as long between compressor fill-ups before you have enough air to run the air tool.

That will quite possibly mean that you will wear out the compressor sooner, particularly if you are exceeding that model’s duty cycle.

Simply, not enough air pressure to run the air tool means – assuming the air compressor is running normally – that your air compressor is too small for the job.

Over To You

Have a question about a replacement air gauge? Help yourself to the comment box 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 COMMENT

  1. My husband works in a mechanics shop and some of his equipment has gotten old, so I’m considering getting him some new equipment, particularly a new gage. Your tip to take it in to a shop to ensure that the new gauge will match his old one is a good one, and I’ll definitely keep in mind the 1 1/2″ face you mentioned as something to fall back on. His old one is a back mount type, as you mentioned. Thanks. RH.

Leave a Reply to Rhianna Hawk Cancel reply

Please enter your comment!
Please enter your name here