How to Read An Air Compressor Gauge

You finally have the right air compressor for your industrial application, and it seems to be working flawlessly. However, unless you understand how to read the pressure gauge on an industrial air compressor, you can’t be sure if it’s doing the job it’s supposed to. If it’s not, you may not find out before it’s too late. Here’s the information you need on how to read an air compressor pressure gauge and what to do if you don’t like what you see.

In This Article

Air compressor pressure gauges measure pressure in pounds per square inch (PSI), usually ranging from 0 to around 250, depending upon the machine and the types of gauges on an air compressor. The PSI rating of a compressor indicates the amount of air pressure the unit will generate in a square inch. For example, if an air compressor has a maximum PSI rating of 125, the machine will produce 125 pounds of air pressure per square inch at times of peak performance.

Tank Air Gauge vs. Tank Pressure Regulator Air Gauge

Typical Industrial air compressors have two pressure gauges with needles that display the PSI levels of the two key stages in the pressurization process. The first of these gauges, on the left-hand side, is the regulator air gauge. The regulator air gauge reads the amount of pressure reserved for the tank. The second gauge, which is on the right, is called the tank air gauge. It shows the amount of pressure that gets generated within the tank.

So what do the two different air compressor gauges mean, and why do air compressors have two gauges? The two gauges of an air compressor are essential for a pair of reasons. On the one hand, each gauge lets you know if the system is healthy. Moreover, each gauge helps you determine flow rates and how energy gets generated inside the tank for use as air power.

If the pressure reading on the left gauge is weak, the compressor will not be able to pressurize the air to a sufficient level for your end-point applications. Consequently, you will not see a favorable reading on the right gauge. Ideally, you would be able to use an air compressor regulator according to the needs of your pneumatic applications and have the compressor generate the required level of air pressurization.

For the readings to be favorable on the right gauge, you will also need to have a healthy set of internal factors within the air compressor. In a rotary screw compressor, you will need to have an airtight, rust-free pair of rotors that can rotate adequately. In a reciprocating compressor, you will need to have airtight, rust-free pressurization chambers, and the piston will need to operate at the proper speed. If moving metal parts receive insufficient lubrication, corrosive friction will result. If condensation occurs within the compressor, rust could take root and eat its way through various metal parts.

A machine that reads favorably on both PSI gauges will generally be in a ventilated room with relatively cool, clean air. The room should be free of humidity, which makes it more difficult for air to pressurize. Even though most air compressors feature water and oil separators, these components can swiftly become hampered if too much moisture or oily mist enters the machine. The real objective is to keep moisture and dirt levels as low as possible within the ambient air, so the filters and separators can extract what remains of those elements within a healthy ambient setting.

Tips for Maximum PSI Output

The purpose of the two gauges is to differentiate the regulation of air pressure sent to the tank from the pressurization intensity that occurs inside the tank. If the pressure of the ambient air is at a favorable level of around 14.7 PSI, the compressor tank should be able to pressurize this air to the maximum PSI as indicated on the machine.

Of course, various factors affect the compressor’s ability to operate at its peak performance level. One crucial factor is the quality of the incoming ambient air, which will only pressurize at 125 PSI if the conditions are favorable from the outset. If the air is humid or dirty as it enters the inlet valves that lead to the compression chamber, the compressor will not be able to pressurize that air to the maximum level indicated on the machine specs.

Therefore, if you wish to run a pneumatic application that requires maximum PSI, you should be able to do so, providing the ambient air is cold, dry and clean. Likewise, if you run several air tools simultaneously and the combined PSI requirements take the compressor to its limits, it should still keep up with your demands as long as the inlet air is favorable.

For a task like sanding, you would need a constant high level of air pressure. For air-powered screws, riveters and nailing tools, you would need a more moderate level of air pressure, delivered at controlled rates. To meet these needs, the settings on the compressor would need to be within favorable ambient surroundings.

A machine will often give poor readings if the ambient conditions are unfavorable for generating air pressure. For example, if your compressor is in a stuffy room where the air is hot and humid, the inlet valves will not receive air supplies favorable for pressurization. The filters and separators will get overworked when extracting water and oil from the incoming air. Ultimately, the pressurization will become compromised, resulting in insufficient PSI levels in the outgoing air.

How to Read a PSI Gauge

Why It's Important to Know How to Read An Air Compressor Gauge

Reading your compressed air pressure gauge is as simple as reading a temperature gauge or a car odometer. All you have to do is:

  1. Determine the units your pressure gauge uses and the difference between each numerically marked unit. For example, your gauge may show measurements for 0, 100, 200, etc., PSI, which means there is a 100 PSI difference between each major unit.
  2. Count the spaces between the marked units to figure out how many PSI units each space represents. If the example gauge has 10 spaces, then each space represents 10 units.

While it’s easy to get a read on your PSI gauge, you should make sure you study all gauges before you start using them so that you can quickly note the pressure amount while your compressor is working. This strategy can save you a lot of time and stress in the future by helping you understand every part of your compressor from the moment you set it up.

What Are Proper Air Compression Levels?

Optimal industrial air compression levels will depend upon the size of your air compressor and the specific application in which you are using the air compressor. If you call Fluid Aire Dynamics, one of our experts can help you establish what the right compression levels are for your air compressor.

Air compressors are useful in a range of industries for various applications. In the automotive industry, air compressors power the robotic arms that piece heavy auto-body parts together along production lines. Pressurized air also powers the pneumatic tools workers use to fasten auto parts into place. At the end of the line, compressed air plays a critical role in the sanding and painting functions that place the finishing touches on newly assembled automobiles.

A similar set of complex processes come into play at factories that produce home furnishings and bottled beverages for consumers. For example, a bottling factory will use compressed air to mold each bottle into shape. From there, bottles get filled, sealed and labeled with air-powered equipment.

For large-scale industrial processes like auto assembly and bottling, factories usually use rotary screw air compressors. Rotary screw models draw air through an inlet and pass it through the rotors of two counter-turning screws, which pressurize the air into power. Rotary screw compressors are generally large units that yield maximum PSI levels for demanding applications.

Large factory settings employ various pneumatic processes with varying needs of time, pressure and consistency. Powering fastening tools requires pressure on a moment-by-moment basis as workers pass successive parts down the assembly line. Applications like air drying, sanding and painting require a more continuous supply of air pressure. Rotary screw compressors are the best option in these environments because the cooling systems in screw compressors come optimized for constant use.

What Are Proper Air Compression Levels?

Depending on the number of processes at hand, a factory might need two or three rotary screw compressors of considerable size and capacity. To ensure a nonstop air supply, most factories will have one backup compressor in addition to the one or two primary units that power various pneumatic applications during each shift. For best results, factories place rotary screw compressors in ventilated rooms, sectioned off from the factory floor. Most pneumatic tools receive pressurized air through an arrangement of hoses and tubes that connect to the unit.

Not all professional air-powered processes necessitate the use of large compressors. In auto-repair shops and other small settings, reciprocating compressors are often the preferable option. Reciprocating models are smaller and usually portable units that can fit into narrower spaces.

In a reciprocating compressor, a crankshaft sucks air into the unit and compresses it with a piston within a pressurization chamber. Single-stage models release the air to hoses for use in various end-point applications. In a two-stage reciprocating compressor, the pressurized air moves to a second, smaller chamber for double pressurization at a higher level.

Reciprocating compressors are valuable because of their portability and compactness. However, reciprocating compressors generally require more frequent maintenance than rotary screw models due to the number of internal parts involved.

Regulating Your Air Compressor Levels

Every time you attach a new tool to your air compressor, you should adjust the pressure levels to ensure you’re using the right PSI levels for that attachment. To learn how to do so, check out our comprehensive guide on compressor regulation.

If your regulation process goes smoothly, you can get right to work with your tools. However, sometimes you’ll discover that the pressure levels aren’t where they should be no matter what you try. In that case, you may need to do some troubleshooting.

What Do I Do If My Air Compression Levels Are Too High or Too Low?

If the pressure levels in your air tank are not at the PSI you need them to be, you can adjust the compressor regulator until you are getting the proper flow and pressure. If this does not work, you may need a more powerful air compressor unit, or your unit may need repair.


Before you attempt to correct your compressor’s pressure levels, be sure you check out the gauges themselves. There are many reasons why a gauge might become inaccurate or stop working at all, such as:

  • Corrosion, usually caused by excessive humidity.
  • The needle or gauge cover breaking.
  • A needle shaft failing.

A good way to tell if your gauge is reading properly is to disconnect it from your equipment. When you do this, it should read zero, as it’s not currently measuring air pressure. While this method may not solve the issue, it’s a good starting point if you want to know how accurate your gauge is.

If you’ve noticed that your air compressor isn’t working as well as it used to, though, then the issue is likely more comprehensive than a broken gauge. Once you determine whether your air pressure is too high or low, there are several steps you can take to resolve it.

What to Do If Air Compressor Pressure Is Too High

Each pneumatic tool requires a certain level of air power to work correctly. If you have several tools in use simultaneously, the compressor will operate at a PSI level that accommodates the tool with the highest-pressure application. That can be problematic if a major disparity exists between the highest- and lowest-pressure applications. For the latter use, the excessive air pressure could send too much power through the pneumatic tool in question, which could also prove wasteful from an energy standpoint.

How to Fix High Compressor Pressure

To stop the pressure from overpowering your low-pressure applications, attach your high- and low-pressure tools to different systems. Connect the high-pressure tools to a compressor with maximum PSI, and attach the low-pressure tools to a separate unit programmed for moderate highs.

On a newer system, the easiest way to save energy is to set it for output pressure requirements. If you operate a multiple-use system with new and old equipment, you might need to retrofit some of your older equipment for lower pressure settings. If it isn’t possible to retrofit specific components, you might need to move those parts to a separate system designed to operate at higher settings when necessary.

To save energy and increase the lifespan of your air compressor, set the system pressure level to the minimum limit required for your operations. Contrary to popular belief, maximum pressure levels do not boost system efficiency. On the contrary, setting your system to its maximum pressure level will merely shorten its lifespan. A minimum setting will save energy and increase the service life of your air compressor.

What to Do If Air Compressor Pressure Is Too Low

When air compressor pressure is too low, it will often be due to an unfavorable set of environmental factors. Most commonly, this concern comes down to an issue with pressure dew point. Pressure dew point refers to the temperature at which the air becomes too saturated with moisture and begins to condense.

If the unit is in a humid setting with no ventilation, the air will generally contain too much moisture to pressurize sufficiently. If internal parts within the compressor have eroded because of age or corrosion, that could also be an inhibiting factor.

How to Fix Low Compressor Pressure

To eliminate external factors that might inhibit your machine’s performance, move the unit to an area more ideally suited for an air compressor. For example, if your compressor is currently in a hot, foggy room, arrange a space in a cooler, ventilated area and relocate your compressor to that spot.

The air that goes into the compressor should be cool, clean and relatively free of moisture. If necessary, install desiccant air dryers in the room to prevent condensation buildup. If your machine doesn’t have one built-in, it may also be helpful to invest in a monitor gauge that displays the pressure dew point of your compressor so you can quickly adjust when it falls out of normal range.

If the pressure is still exceedingly low despite a favorable set of external factors, the issue might be down to the internal parts of your compressor. Inspect the machine for any dirt or problems, such as gunky filters or rusty parts. If a new filter and a clean tray do not do the trick, it may be time to contact a professional.

Contact Fluid Aire Dynamics for Your Air Compressor Needs

When it comes to air compressors, Fluid Aire Dynamics has all the knowledge you will ever need. All of our superior system designs meet Compressed Air & Gas Institute (CAGI), Compressed Gas Association (CGA), ANSI and ASME standards so you can feel safe and confident while operating them. If there are ever any concerns, we provide 24/7 emergency service so you can get back to business immediately.

We have been solving compressed air and gas tank problems for customers in businesses throughout Pennsylvania, New Jersey, Maryland, Delaware and Virginia for over 30 years. We have a wide range of quality air compressors and know how all the best air compressors work, what they can do and how you can best put them to work for you and your business. Industries ranging from pharmaceutical production to hospitality management can benefit from these top-of-the-line machines and our comprehensive understanding of air compressor function.

If you have any questions at all about air compressors, all you have to do is contact us online today or give us a call at 610-913-9100. We’ll be in touch as soon as possible to answer any air compressor questions you may have. We pride ourselves on our excellent customer service, and we won’t stop working with you until we’ve resolved your issues. Get your free estimate now.