Air compressors are machines that create and use compressed air to power pneumatic tools like nailers, staplers, impact wrenches and paint sprayers. Contractors and technicians use pneumatic tools for framing, roofing, finish work, automotive repairs and bodywork. Homeowners also use compressors for home-improvement projects and lighter applications like inflating tires or sports equipment.
There are many types of air compressors, each designed for specific applications. Our guide should help you determine which air compressor is best for you.
Air compressors can be used for a variety of jobs and applications, but for the sake of simplicity, we've broken it down into two categories: consumer use and professional use.
Consumer use: Consumer-grade air compressors are typically single-tank, oil-less models and are affordably priced. These types of compressors are made for minor household tasks, like inflating tires, toys and sports equipment. They are also suitable for occasional pneumatic tool use. If you do a lot of home-improvement projects or have a hobby that requires frequent use of your pneumatic tools, a consumer-grade compressor will not be sufficient.
Professional use: If you use your pneumatic tool frequently or need to power multiple tools, go for a professional-grade air compressor. There are many types of professional-grade compressors, but one common factor is they tend to be “oil-lubricated”, not “oil-less”. They have higher hp and cfm ratings, and they typically have twin tanks or large single tanks. They are usually more expensive than consumer-grade air compressors, but they are also more powerful and have a longer life. Portable compressors are usually suitable for contractors and skilled do-it-yourselfers. Stationary compressors are best for the workshops and garages of serious hobbyists and professionals (woodworkers, automotive repair, etc.)
|Runs on standard household voltage between 110 and 120 volts. (Compressors with 2HP motors need a 220- to 240-volt outlet). Ideal for indoor tasks because electric air compressors don't emit exhaust. Shop Electric Air Compressors.|
|Ideal for job site applications. Requires gas to run and emits fumes, so should be used for outdoor applications or at well-ventilated work sites. Shop Gas-Powered Air Compressors.|
Oil-Less or Oil-Free
|Low-maintenance design that doesn’t require the user to add oil. Oil-free models tend to burn up their engine more quickly, and the “oil-free” sealed housing makes them next to impossible to service when they are in need of repair. Oil-free air compressors are typically louder and less expensive than other compressors, and they tend to have a shorter life. They perform well for small to medium-scale applications. The low cost makes oil-less compressors ideal household compressors.|
Pancake or Hotdog
|Smallest and lightest model. Usually has one tank, lower CFM and a less powerful motor. Pancake or Hotdog compressors are best for occasional, small scale jobs and household applications like inflating tires and sports equipment.|
|Most non-stationary compressors are considered “portable,” but the degree of portability varies wildly. For instance, a 10 lbs pancake compressor and a 60 lbs wheelbarrow compressor are both considered “portable”.|
|Has one piston that compresses and transfers air to tank. They are less efficient than two stage compressors at acheiving higher pressures, and are typically used for applications where a lower PSI is needed, (at or less than 120 PSI).|
|Compressors with one air storage tank. Single vs Twin tank is primarily a product design issue, twin tanks are sometimes more portable, but having one or two tanks doesn’t seriously impact the compressor’s performance. Single-tank compressors can hold just as much air as twin tank compressors. The important issue is to look at the total volume a compressor can hold.|
|Typically stand-up compressors installed in workshops and garages. Used for heavy-duty or commercial applications.|
|Compressors with two air storage tanks. Twin tanks can allow the compressor to have a lower profile and a lower center of gravity, making it easier to transport. Aside from portability, the number of tanks doesn’t impact the compressor’s performance. The important issue is to look at the total volume a compressor can hold.|
|Has two pistons that compress and transfer air to tank. The first piston compresses air and pushes it through check valve to the second piston. The second piston compresses air further and transfers it to the storage tank. Two-stage compressors are typically found on heavy-duty/commercial compressors with max rating above 150 PSI. Ideal for continuous use or in shops.|
|Portable air compressor with wheels and handles, similar to a wheelbarrow. Having wheels doesn’t significantly impact a compressor’s performance. It is simply a design feature, intended to make heavy compressors easier to move.|
For professionals, Rolair's "BULL" compressor (FC2002) gives you the best value. It has a 2 HP motor with a single-stage, splash lubricated pump. It features the standard Rolair craftsmanship: stainless steel reed valves, ball bearings and cast-iron cylinder, and it's very competitively priced. Essentially, you get a top-of-the-line pump without breaking the bank. You can run 1-2 roofing or framing guns off of this compressor.
If you need to run several guns at the same time, we recommend Rolair's 4090HK17. It's a gas-powered, single stage compressor with a 5.5 HP Honda engine. The pump is made to Rolair standards: ball bearings, cast-iron twin cylinders, hardened steel valve plates, aluminum alloy connecting rods, etc. This compressor has very large capacity (8.9 cubic feet of free air at 100 PSI) and can run 3-5 framing guns or 4-7 roofing guns.
Makita's 2.5 HP air compressor (MAC2400) is a reliable choice for professionals. The cast iron pump is oil-lubricated and puts out 4.2 CFM at 90 PSI. It operates reletively quietly (79 db) and the twin tanks store a total of 4.2 gallons. The unique gauge set up is easy to read and monitor.
Rolair's JC10 Oil-Less compressor is top pick for Toolbarn customers. It has a 1HP motor and single stage pump with ball bearings, cast-aluminum cylinders and stainless steel reed valves. It's highly portable (only 39 lbs), and runs very quietly for an oil-less model (60 db.) It has an output of 2.35 CFM at 90 PSI.
Makita's MAC700 air comrpressor is a good little hot dog compressor. The 2 HP motor is very quiet (80 db) and has a quick recovery time. The oil-lubricated pump produce 3.3 SCFM at 90 PSI. This model is a favorite among beverage industry professionals for running soda carbonation guns.
Absolute Pressure: The existing gauge pressure plus atmospheric pressure measured from absolute zero
Aftercooler: Part of an air compressor that dissipates heat caused by compression and allows for the removal of moisture from the compressed air or gas
Air-Cooling System: Cools the pumping machinery to extend motor life
Air Receiver: The tank where compressed air is stored and delivered
Atmospheric Pressure: Pressure at a specific altitude; this is a factor for people working at high altitudes
Brake Horsepower: The total power input required to compress and deliver a given quantity of air
CFM: Cubic Feet per Minute, a measurement of air volume over time
PSI: Pounds per Square Inch, a measurement of air pressure or force
Roll Cage: Protects the compressor from being damaged, crushed or battered
SCFM: Standard Cubic Feet per Minutes, a measurement of air volume over time at 60° Fahrenheit (15.6° Celsius). Because air expands and contracts at different temperatures, some manufacturers use scfm rather than cfm to establish consistent measurements.
Thermal Overload Switch: Automatically shuts off motor if it overheats. This increases the length of tool life and increases strength
Unloaded Horsepower: The power that is consumed to overcome the frictional losses when operating in an unloaded condition
Before you decide which type of air compressor to buy, ask yourself these questions:
How will you be using your compressor?
If you just need to inflate tires and handle occasional home projects, stick to less expensive consumer models like oil-less and pancake compressors. If you need one for regular or heavy duty use, opt for a professional grade model with a more powerful motor and larger air tanks. (Either twin tanks or a large single tank will do.) Check the owner’s manual of your tools to find out the air requirements.
Where will you be using your compressor?
Will your compressor remain in one spot in your workshop, or will you need to move it from project to project? If you need a portable compressor, be careful you don’t sacrifice performance for portability. Smaller models are easier to carry around, but they may not be able to sufficiently power your tools.
From our experts: “The number one mistake people make when choosing an air compressor is going with too small of a model. Everyone wants ultra-portable machines, but smaller compressors have lower cfm and smaller tanks, which means the motor will run more frequently, use more electricity and burn out more quickly. It’s better to spend $400 on a larger model that exceeds your requirements, rather than $150 on a compact model that can’t power your tools and won’t last very long. That compact model won’t save you time or money in the long run.”-Patrick
What size air compressor do I need?
There are two basic steps for choosing the right size air compressor:
1. Figure out your tool's air requirements
All air tools have a force air requirement, measured in pounds per square inch (psi), and a volume requirement, measured in cubic feet per minute (cfm). Air requirements vary between types of tools and even between manufacturers. You should always check the owner's manual to find a tool’s air requirement, but the chart below gives a general range of the pressure and volume requirements of different classes of tools.
2. Check the compressor’s cfm rating
A compressor must at least meet the maximum cfm of your specific air tool. This capacity should be sufficient for occasional use of most air tools, and frequent use of tools that “burst” like nail and staple guns. If you need your tools frequently, use multiple tools simultaneously or have “constant use” tools like random orbit sanders, then increase the cfm requirement.
Most compressors will list their cfm at 90 psi or 120 psi. These are simply baseline values that represent using an “average” tool. If your tools require significantly less or more than the displayed psi, check the compressor’s owner’s manual. It should have a complete list of the compressor’s cfm at different psi’s.
If you need to power several different pneumatic tools, use the tool with the highest force air requirements when picking your compressor. If you need to power several different tools at the same time on the same compressor, then you should use the total sum of the tools’ force air requirements when picking your compressor. (For instance, if you need to run a 4 cfm @ 90 psi air gun and a 5 cfm @ 90 psi sander at the same time, then you need a compressor that produces at least 9 cfm @ 90 psi.)
Note: When checking a compressor's cfm, look at the “Delivered cfm” or “Free cfm” rating. Do not use the “Displaced cfm”. Displaced cfm is the air flow the compressor produces in a perfect environment working at 100% efficiency. But no compressor is 100% efficient, no matter how new, and most jobs sites aren't “perfect environments.” The “Delivered cfm” rating will give you a more reliable representation of how the compressor will typically perform.
What size air tank do I need?
There are no hard and fast rules for choosing a compressor’s tank size, but we suggest you get the largest, practical tank you can afford. There are two main reasons why bigger is better when it comes to air tank size: motor strain and condensation.
A compressor uses its motor or engine to help fill its air tanks with compressed air. When the volume of air in the tank falls to a certain point, the motor will switch on and begin to fill the tanks again. Frequently turning off and on strains the motor, and shortens the life of the compressor. Because smaller air tanks hold a smaller volume of air, they need to be filled more frequently, and so they switch on their motors more frequently. A larger tank means you can use your tools for longer periods of time before the motor must switch on again. This reduces strain on the motor and prolongs the life of the compressor.
When air is compressed, it becomes hot and holds more moisture. If compressed air is used when it’s still warm and full of moisture, condensation can build up in your air lines and damage your compressor and tools. If the air tanks are too small for your needs, the compressed air will be used right away, before it has cooled. Larger tanks hold the air for longer, giving it a chance to cool and release moisture before entering the air lines.
We should note that a larger air tank adds bulk, weight and cost to a compressor. Despite these issues, we still recommend getting the largest practical size tank you can afford. (A 20 gallon tank will hold a lot of air, but it will also be hard to move from job site to job site. You must decide what “practical” means for you.)
While there are several factors to consider, don’t get caught up in trying to calculate the “perfect” size air tank. Remember, cfm and hp are the most important elements when comparing compressors. Once you’ve narrowed your selection, tank size may be one of the factors that help you make your final decision.
Note: The drawbacks to smaller tanks are important for people who use their air tools frequently. If you plan to use your compressor for household tasks and occasional small projects, these drawbacks are not significant concerns.
Does an air compressor's horsepower rating matter?
Yes. In a nutshell, horsepower can improve a compressor’s recovery time, but it won't make your nailer any faster or more powerful.
Horsepower (hp) in a compressor refers to the power of the engine or motor. The motor powers the compressor pump, which fills the tank with compressed air. Higher horsepower can help the pump fill the air tank more efficiently, reducing your recovery time. However, horsepower does not affect airflow from the tank to the tool. The cfm and psi ratings are more important when it comes to powering your tools.
The bottom line: when selecting your compressor, don't sacrifice a good cfm rate for lots of horsepower; you won't get the performance you need.
Note: When checking a compressor's horsepower, look at the “Running Horsepower” and not the “Peak Horsepower”. Peak horsepower represents the surge of power a motor has when first starting and can be 1.5 to 3 times the amount of power generated during normal operation.
Can I run an air compressor on a generator?
We do not recommend using a generator to power your compressor. Air compressors can be seriously damaged by the generator’s sudden fluctuations in power. This is considered “improper use” by most manufacturers, and it will void the warranty. If you routinely work in areas without a reliable power supply, a gas-powered air compressor may be the best option for you.
If you are having difficulty powering your electric air compressor, make sure you are using the correct length and gauge of power cord. (The owner’s manual should provide this information). Cords that are too long are less efficient at supplying power. It’s always better to use a shorter extension cord and a longer hose.
I have more questions!
We'd love to help. Give us a call at 866-597-3850 (Monday - Friday, 8am to 5pm CDT). Or email us at firstname.lastname@example.org.
Rolair provides a list of things to check when dealing with air compressors. To find the owner's manual for your specific compressor from Rol Air click here and download the manual. Below is Rolair's troubleshooting suggestions for air compressor users. NOTE: before attempting any changes or repairs to your compressor, familiarize yourself with each system control component. Rolair suggests that before checking for troubleshooting, always drain the tank pressure completely, make sure the power cord is unplugged and the unit has time to cool.