Best Air Compressor

After a series of rigorous tests, we singled out the California Air Tools 10020C as the best compressor. What drew us to it was its high CFM, the large tank, powerful motor, and the oil-free pump.

Our step-up pick was the California Air Tools 6010LFC. We admired its quiet operation, oil-less pump, high CFM, sizeable tank and low amp draw for minimal breaker tripping.

For the budget pick, we chose the Dewalt DWFP55130. One of the best things about it is its low weight, which makes it highly portable. We also liked its durable, oil-free pump and the fact that it is easy to start and has minimal breaker tripping.

A Little Background

Air compressors are mechanical devices designed to convert power into potential energy which is stored as pressurized air. They use electric motors, diesel and gasoline engines, among other power sources.

Compressed air is crucial in industrial processes, where it is used for energy transfer. It is used in power tools like drills, wenches, and air hammers. It is also useful for atomizing paint, operating air cylinders for automation and in propelling vehicles.

Underwater divers use pressurized air to breathe underwater, carrying it in a high-pressure diving cylinder or being supplied with it from the surface at lower pressure using a diver’s umbilical. The same kind of breathing apparatus is also used by mine rescue workers, firefighters, and industrial workers operating in hazardous atmospheres.

These are just a few of the applications of pressurized air. In fact, it is so important that in Europe, 10% of all industrial electricity consumption goes to the production of compressed air: 80 terawatt hours consumption per year.

Most people use compressors for repairs around the house, mechanic work, and DIY projects. They are a must-have tool in every garage. They are also useful in carpentry. You can find them in your corner gas station as well as in big manufacturing plants.

The best thing about compressed air is that it cancels the need for every tool to have a bulky motor. Its motor converts electrical energy into kinetic energy which enables the tool to execute its given function. So instead of being heavy and unwieldy, tools are built light, compact, and easy-to-handle, running quietly. Best of all, it means that tools have fewer parts which need maintenance or replacement.

Types of Air Compressors

There are different parameters you can use to classify them.

According to the Quantity of Pressure Discharged:

1.  Low-pressure air compressors (LPACs) – These discharge a pressure of up to 150 psi (pounds per square inch).

2.  Medium-pressure air compressors (MPACs) – They discharge a pressure of 150 psi to 100 psi.

3.  High-pressure air compressors (HPACs) – They discharge a pressure above 1,000 psi.

According to the Design and Principle of Operation:

1.  Rotary-screw compressors

2.  Turbo compressors

According to the Compression Technique:

1.  Positive-displacement compressors – These can in turn be subdivided into three main types: Piston-type, rotary-screw, and vane compressors

2.  Roto-dynamic compressors

Parts of a Compressor

The basic components are:

1.  Electric Motor – It powers the pump: by driving a pulley and two belts which transfer power to the pump pistons using a flywheel and a crankshaft. The flywheel fan cools the pump.

2.  Pump –It compresses air, then releases it into the receiver.

3.  Receiver Tank – This is where the compressed air is stored. It includes a check valve at its receiver inlet that ensures the pressurized air does not flow back into the pump.

How They Work

The simple explanation: An inlet sucks air into the machine. The piston compresses it, after it is released through the discharge valve.

There are two phases to the process:

1.  Compression

2.  Release.

There are multiple techniques used in compression, such as centrifugal compression, reciprocating pistons and rotary screws. After compression, the air is discharged in a quick burst that releases kinetic energy which is harnessed for tasks such as tire-filling, activating pneumatic devices and cleaning operations. The quantity released after compression also varies, and is measured in cubic feet per minute (CFM). The greater your device’s horsepower, the more powerful its air delivery.

How positive-displacement compressors work: part of the device performs the air intake. The device minimizes the amount of space in the chamber, thus pressurizing the air molecules. Compressed air is discharged by the opening of a valve.

How piston-type compressors work: the piston’s motion brings air into the chamber by way of an intake valve. Take for instance, an automotive-type piston which comprises a crankshaft connected to a rod, and topped by a cylinder within another cylinder. The movements of the crankshaft and rod cause the cylinder to be in constant, up-and-down motion, which enables air intake and release. The exterior cylinder has an inlet port, outlet port, and two valves housed in three chambers; with one chamber being the inlet chamber, the second the outlet chamber, and the third the pistons cylindrical chamber. The repetitive rising and dropping of the piston leads to the forcing of more and more air into the outlet chamber, causing more compression. Air delivery happens when the user releases the outlet chamber.

Rotary screw compressors work by creating an air chamber between the helical screws and their housing. The turning of the screws causes a reduction of air chamber volume, leading to compression of the air between the screws.

Vane compressors comprise a slotted rotor inside a stator, which is the fixed housing area of the rotor.  The rotor’s blade orientation is such that the rotor’s revolution drives air into a chamber, compressing it with each blade rotation.

Centrifugal compressors use a spinning impeller, which is a type of rotor, to accelerate the air within. A diffuser decelerates the air, a process which raises the air pressure. In this process, the air heats up and must be cooled by an intercooler.

How We Picked

Airflow Rate

It is measured in units called CFM (cubic feet per minute). It is a measure of how fast your machine is supplying air. It is the most important factor to consider. Should your tool use air faster than the machine supplies it, you will have to pause and give it a moment to catch up. Manufacturers test their machines at a pressure of 90 PSI, which is the average setting for a nail gun.

Tank Size

Most small-scale compressors have tanks ranging in capacity from 1 to 6 gallons. The larger the tank is, the more air it can hold for use before there is a drop in pressure and the motor kicks on to refill the tank. A large tank will enable you to work for longer periods. With smaller tanks, you have to stop frequently and wait for the tank to refill.

Noise

Noise is measured in decibels, and some machines can be as loud as 90 dB. The difference between 70 dB and 80 dB is immense. A conversation between two people marks 60 dB; on the other hand, an 80 dB noise level in your workplace from 9 to 5 may lead to hearing loss. The best compression machines are quiet - make sure yours is below 75 dB.

Portability

Portability depends on weight and power source. The lighter the machine, the more portable it is. Electric compressors tend to have power cords, which hinders their portability. Gas-powered machines are more portable. Portability, however, is not a measure of excellence – it depends on your preference, environment and intention.

Our Pick

Our best compressor is the California Air Tools 10020C. One of the key features we scrutinized when searching for the best compressor is how much air each device delivers. Air delivery is measured in Cubic Feet per Minute (CFM), a unit which specifies how much air a machine can deliver at a certain pressure (90 PSI is the standard pressure setting). So CFM tells you how fast your machine can supply air. The 10020C does 6.40 CFM at 40 PSI and 5.30 CFM at 90 PSI.

CFM is the most important feature. This is why the 10020C managed to clinch the top position as the best air compressor despite not being as quiet as our second-best pick. It has an impressive CFM. Its noise level is 70 decibels.

Another feature we loved was the size of the tank. At 10 gallons, it can accommodate enough air to keep you working for longer periods. In addition, the machine has wheels, making it easier to cart around your work environment. Another plus is that the pump is oil free (less maintenance and costs) and the motor runs at 2.0 Hp, with a draw of 14 amps. The oil-free pump enables you to use the device in a variety of temperatures and in uneven terrains.

Flaws but not Deal-breakers

It is not as quiet as some of the other machines on this list. While the quietest ones on the list operate at 60 dB, the 10020C does 70 dB. But given its high airflow rate, that’s certainly not a deal-breaker.

Step-up Pick

We have reserved the second-best position for the California Air Tools 6010LFC. If you like working while watching TV or listening to music in the background, this is one of the best choices for you, since it is so quiet. Operating at 60 decibels, it is a quiet machine that enables you to work without being a nuisance to others.

It’s an oil-less machine. Such compression machines are the best, since they are easier to maintain. You don’t have to stress about changing or checking the oil in your machine. It also means they are free from contaminants, keeping the air cleaner.

CFM is the first thing you tick of the checklist when shopping for the best compressor. Our second-best pick has a CFM of 4.0 at 40 PSI and 3.0 at 90 PSI, with a 125 max PSI. This is quite impressive. Other features include a 6-gallon steel tank, weighing 54 lbs. and a motor/pump that, according to tests, should give you a minimum life of 4000 hours before it wears, which is better than what many brands offer. The motor has a draw of 7.6 amps.

Budget Pick

Our choice for the third-best compressor is the Dewalt DWFP55130. At 71.5dB, you can work without having to put on ear plugs. It is almost like having a dishwasher running.

The Dewalt DWFP55130 is lightweight, weighing only 36 pounds. In addition, it is a slim device, measuring just 12.5 inches. This compact design makes it easy to handle and store. This also makes it portable, an important factor since these machines have such a broad range of applications.

The DWFP55130 requires a PSI of 90 PSI (pressure per square inch), which is the unit used to quantify the pressure of the air delivered by the compressors. It delivers 3.0 CFM at 90 PSI. Other features on the The DWFP55130 requires a PSI of 90 include a 2.5 gallon tank, a max PSI of 200, a durable oil-free pump and a 12-amp-draw motor. It is also easy to start and has minimal breaker tripping.

Best Compressor For DIY Projects

Our best compressor for DIY projects is the Campbell Hausfield DC080500.  Its best feature is its quietness. It operates at 68 decibels, ensuring a quiet working environment for your DIY projects.

The DC080500 has a tank size capacity of 8 gallons. The larger the tank, the more air it can hold, enabling you to use the machine a bit more before the pressure drops and the motor has to kick on to refill the tank. This allows you to work for longer periods.

However, a large tank should never be a substitute for airflow rate – the CFM matters more. The DC080500 delivers 2.4 CFM at 90 PSI. It has a max PSI of 125.

The DC080500 is the best option for DIY projects and small-scale tasks at home such as hobby painting, inflation, stapling, nailing and fastening. Other attractive features include its large wheels, rubber-grip steel handle, oil-free dual piston pump and a 17-piece accessory kit.

Best Compressor for Professional Use

We settled on the Industrial Air ILA3606056 as the best compressor for professionals. It is the best option for you if you run a mechanic shop, if you have a service truck, and other similar uses. It contains heavy-duty components that make it the best machine for use in the toughest, most demanding conditions. It has a cast iron, twin cylinder with oil-lubricated pump, thermally stable cast iron cylinder body and a one-piece cast iron crankcase among other heavy-duty components.

If you thought ten gallons made for a big tank, this one has 60 gallons. That’s what makes it the best compression machine for use on a larger scale. In addition, it has a CFM of 13.4 at 40 PSI and 11.5 at 90 PSI, a voltage of 208 to 240 voltages and a running horsepower of 3.7. The maximum pressure is 155 PSI. It comes with a pressure gauge and on/off switch.

Best Noise-free Air Compressor

If you work in an environment where noise pollution is frowned on, the best machine for you is the California Air Tools 5510SE. If a conversation between two people marks a noise level of 60 dB, then this machine must be one of the quietest because it also marks just 60 dB. You can work without distracting everyone else in your immediate vicinity.

Quietness is not its only impressive attribute. This being a best list, we made sure that the other features were just as appealing. The 5510SE has a 3.10 CFM at 40 PSI and 2.20 CFM at 90 PSI, with a 120 max PSI. You can also count on low maintenance costs and cleaner air for better tool operation since it has an oil-free pump. In addition, it has a thermal overload protector, which protects the motor.

Best Electric Compressor

Our pick for the best electric compressor is the WEN 2289. Electric compressors offer some distinct advantages. They are better than petrol and diesel-fueled machines for a number of reasons. They are affordable. They don’t emit hazardous fumes, so you can use them inside the house. You can connect using your car’s electrical system or battery. They are not as noisy as other types. They are easy to use. Best of all, you can get high-voltage ones for heavy-duty tasks.

The WEN 2289 delivers an airflow rate of 5.0 CFM at 40 PSI and a 4.0 CFM at 90 PSI, which provides long runtime with quick recovery. It has a maximum pressure of 15 PSI. It has an oil-free pump, and therefore does not require any external lubrication, and has a longer life span.

It has a large tank with a capacity of 10 gallons. The tank is constructed with reinforced steel for durability. It also has an easy-to-reach quick drain valve, a rubber-gripped handle and two 7-inch wheels. It is a corded electric compressor.

Best Gas-Powered Compressor

Our choice for best gas-powered compressor went to the Bostitch BTFP02012.  One of the best qualities of gasoline-powered compressors is that they don’t need cords or cables for them to function. That makes them more flexible than electric ones.

This Bostitch machine provides an airflow rate of 2.6 CFM at 90 PSI. It is oil-free, which translates into lower maintenance costs. However, it is not as quiet as some of the other machines on this list. It has a noise rating of 78.5 decibels. It has a highly efficient motor which enables easy start-up, even in cold weather.

Best Portable Compressor

One of the best things about compressors is their versatility. There are so many things you can do with them, and not just in your house or garage. For instance, you can use them in tire-filling, which is something you might need to do from anywhere. In this case, portability is a critical aspect. Of all the machines we tested, we felt that the best portable compressor is the VIAIR 400P.

Portable compressors are usually small and underpowered. The best thing about the VIAIR 400P is that it combines the size of a portable machine with the power of a stationary one. With this machine, you can inflate up to 33-inch tires within a short time.

It has a 12-volt battery and also comes with alligator clamps. It also has an open-ended tire inflation hose with a 100 PSI pressure gauge. It has a maximum pressure of 150 PSI. Other important features include an 8-foot power cable and an inline fuse holder. It has a 40-amp inline fuse.

Best Stationary Compressor

Stationary compressors have several advantages over the portable ones. Since they are stationary, they can be as large in size as possible, which means they can be built to accommodate higher pressures and volumes. Horsepower requirements, electrical components, chassis construction, and pumping systems are bigger than those in lightweight, portable devices. After our reviews, we settled on the Briggs & Stratton 074040-0.

The Briggs & Stratton 074040-0 delivers an airflow rate of 2.4 CFM at 90 PSI.  It has an oil-free pump, solid, rugged wheels, an integrated control panel, a large on/off switch, a large regulator knob, an adjustable sliding handle, a built-in accessory storage box and a 4.5-gallon tank.

The Competition

The ten machines in the list are some of the best in the market. There are others almost as good, though they didn’t make into this best list. They missed out on the list owing to some unimpressive features such as loudness, a low airflow rate, oil-lubricated pumps and small tanks.

Other Frequently Asked Questions

Q: What is the difference between SCFM and CFM?

A: CFM stands for Cubic Feet per Minute, whilst SCFM means Standard Cubic Feet per Minute. SCFM is the volume of a gas’s flow rate when you put it in a controlled environment that has standard pressure, standard temperature and a standardized relative humidity. The standards can vary from place to place (for instance, the standards in Europe are not the same as the standards in America). CFM is air volume occurring at an exact pressure or temperature. While SCFM is volumetric flow rate against a standard, CFM does not involve any standard.

Q: Does max PSI (maximum pressure) matter?

A: It matters up to a point. So long as your machine has a max PSI that is equal to or above 90, it’s alright. 90 PSI is the standard used by most manufacturers. If your machine has a maximum pressure lower than 90, it will not be able to function properly with your tools. However, if your tool requires a higher pressure setting, you will need a compression machine that can deliver that higher setting. One advantage of a higher max PSI, though, is its ability to increase the carrying capacity of a smaller tank.

Q: Why would I use a compressor rather than an alternative power source?

A: Here are a few good reasons:

1.  Lighter tools – Air tools are lighter and smaller than ordinary tools. Since they do not require bulky motors or battery cells, they can be designed and built light and slim.

2.  It is safer than electricity – Electric-powered tools run the risk of starting electric fires, and they can even electrocute you. Compressors ensure your tools are safer, since there is no electricity involved.

3.  Cheaper – The tools are cheaper than electric or hydraulic tools. Additionally, you can use a variety of tools with just one power source.

4.  Less maintenance – The tools have fewer parts requiring regular maintenance or replacements after they wear out.

Q: What’s the difference between oil-free and oil-lubricated pumps?

A: Oil-free pumps are all the rage for a reason. Oil-lubricated pumps have an oil bath that keeps the bearings and walls inside the cylinder lubricated. Piston rings keep the air and oil separate; but since they are not foolproof, some mixing does happen, which may cause problems.

The oil in the air stream may spoil your finish when you are working in woodworking or painting. That’s why oil-free pumps are the best. They have permanently lubricated bearings which require no maintenance, and so there is no oil to contaminate the air stream.

Q: What is the difference between a pump and a compressor?

A: Pumps move fluids (whether liquids or gases) from one place to another, whilst compressors squeeze a gas into a smaller volume and pump it somewhere else. Sometimes these functions may overlap – for instance, in the case of a tire pump, which can both move air and squeeze it into a tighter compartment.

Q: What causes breaker tripping?

A: It happens when you are using a tool, and the pressure in the tank drops to the cut in pressure setting, prompting the machine to restart. In this attempt to restart, the breaker trips or the fuse blows.

If the motor fails to restart for some reason, it continues to draw power, and in doing so may draw enough amperage to overwhelm the capacity of the breaker, and this results in the tripping of the breaker during restart.

Q: What should you check in the event of breaker-tripping during restart?

A: Here are some of the things to check in case the breaker trips during a restart.

1.  The unloader valve - Is the unloader valve working? When the unloader valve fails, compressed air gets trapped over the cylinder, increasing the load which the motor encounters during start-up. That extra load may force the motor to draw excess amperage, which would cause either breaker-tripping or fuse-blowing. To test this hypothesis, unplug your machine, open its tank drain and release all the air within. Plug the machine back in, and flip the ON/OFF switch to on. If no breaker-tripping happens and the machine is able to start, it means that the unloader valve is not working properly: fix it, or replace it.

2.  Check if you are plugging the machine into a power bar or extension cord – Both of these are notorious for throttling power. If so, that would lead to an under-powering of the motor, resulting in an overheated motor that ultimately ends in breaker-tripping during restart. Let the machine cool for about 15 minutes, after which you should attempt to plug it directly into a wall socket – the best being one with a 20-amp breaker and no other electrical devices using power at the moment. Should the machine successfully restart this time round, then you know what the problem is. It is better to add an air hose to your work station than use an extension cord to get the machine closer to your work station. With a long hose, no part will get damaged if it does not get enough air. Electrical devices, on the other hand become overworked if their power supply is not up to the task, and this can lead to electrical maintenance issues.

3.  The pressure switch – Breaker-tripping can be caused by a shorted pressure switch. A drop in the tank’s pressure causes a diaphragm inside the pressure switch to move. The moving diaphragm causes points inside the switch to touch, creating a circuit. This creates a power flow to the motor, which starts it, causing the pump to pump more air into the compressor tank. You should unplug the machine and drain its tank, then close the tank. Keeping the live terminals within the pressure switch in mind, pull off the cover, reset the breaker, and looking inside the pressure switch to observer if any arcing or sparking takes place when you turn back on the machine. There should not be any arcs or sparks. If there are, it might mean that your pressure switch is the problem, and you have to replace it.

4.  Capacitors – Capacity failure may cause fuse-blowing or breaker-tripping at restart.

5.  Motor windings – If they (or any of the electrical connections within the motor) short-circuit, they cause a sudden flow of electricity to the ground, drawing too many amps. Ultimately, however, it is far better to take your machine to an expert skilled in electrical motors and circuitry. Take it to an electrical motor shop to have a load test done; that might explain what part of the motor is shorting.

Q: How does overload relay (thermal block) protect my machine?

A: By continuously sensing the current the electric motor draws, the thermal relay is able to protect the motor (when the current is too high for a long time). It usually comes with these settings:

1.  Dial knob to set the rated motor current

2.  Manual/automatic reset selector

3.  Test button

4.  Reset button

Most people set the trip current at 1.15 to 1.25 times the machine’s normal operation current. The setting must not be so high that the current can damage the motor or wiring in the event of a failure. Should there be a case of breaker tripping, it is better to investigate what caused it before you use the manual reset setting to reset and restart your machine.

The thermal relay has bimetal tripping elements inside it. An increase in current flow through the relay causes the bimetal tripping elements to start getting hotter. Bimetal bends when it gets hot, and becomes straight again when it cools. In case of an overload, a large amount of current is drawn, making the bimetal all hot and bent, causing the thermal relay to trip.

The thermal relay is built in such a way that it trips quickly in the event of a huge overload – within a second. It also trips in the event of a small overload, which takes longer. In this way, the thermal relay is the best thing a motor can have. It protects the motor from damage.

Q: How often should I change the oil?

A: If you own a rotary-screw, you should change oil every 7000 to 8000 hours, and if it’s a reciprocating compressor, change the oil every 3 months. When changing the oil, ensure you turn off the machine, but you don’t have to decompress the tank. The oil may be located either in the sump or in the crankcase. Empty the oil by opening a drain that is below the case. Find the opening through which you are supposed to pour in new oil, and do so. You should change the oil at least once a year, since oil filters are typically only found in larger compressors.

Q: What should I do to maintain my compressor?

A: We will provide you with some tips we have found useful in our own experience:

1.  Study your machine’s manual. It contains tips on how to take good care of it, including some that may be specific to that particular model. Remember that failure to follow the instructions in the manual may cause you to void your warranty.

2.  Drain all moisture from the tanks. Moisture from the air tends to collect in the receiver tank, especially if you live in a humid area. The best tanks come with a valve for draining this moisture, and it’s your job to drain it regularly. Before draining, remember to release the air pressure from the tanks.

3.  Keep the intake vent as clean as possible. Failure to do so will lead to a gradual degradation of your tool. This is especially important when working in dusty or dirty environments.

4.  Regularly check the hoses. Hoses are the veins of your machine. When cracked or corroded, they leak, putting undue strain on other components. Replace them when you discover that they have become cracked or damaged.

5.  Tighten all fasteners. The vibrations of the engine will, over time, loosen the nuts, screws and bolts of the machine. Check on them periodically, and tighten them if any have jiggled loose.

6.  Clean the fuel tank. Periodically cleaning the fuel tank ensures the engine has the best operating conditions. Do so at least once every year to remove any residue that has built up from the fuel. This preserves the engine’s life.

7.  Check the air filters and change them where needed.  Dirty filters allow dirty air to come in. They also force the machine to work harder at air intake. Check the filters regularly, and in case of a heavy dust or dirt buildup, change them. Change them at least every six months, if you are an infrequent user.

8.  Test the safety shutdown system. Some machines have a built-in safety shutdown system. This system shuts off the machine if it starts to get too hot, or when the engine’s oil pressure runs too low.

9.  Clean the heat exchangers. Dirty heat exchangers cannot adequately perform their given task of reducing the machine’s operating temperatures. Clean them regularly to keep the operating temperatures down and increase the machine’s lifespan.

10.  Check and change the oil (see the question preceding this one).

11.  Change the separator element. The separator element prevents excessive use of oil. It must be periodically replaced. Replace it every 1000 hours of operation so as to ensure your machine remains in tip-top condition.

For more tips on how to maintain your machine and keep safe in the process, check out these instructions.

Q: What should I look for in a compressor when shopping?

A: We did an article that listed every factor you should consider when looking for the best compression machine. Check it out. While you are at it, check out our reviews of the best pancake compressors.

Wrapping It Up

We restricted the products in our testing process to those that our regular readers can afford. Otherwise, the very best machines are out of the price range of most people. With that in mind, our pick for the best compressor is the California Air Tools 10020C, which we admired for its relatively large tank, high rate of airflow and its oil-free pump, among other attractive features.

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