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Back to Portable Air Compressor Comparison Last update:

Things to Know Before Buying a Portable Air Compressor

How do portable air compressors work?

image of Portable Air CompressorThe most common type of portable air compressor is reciprocating. Reciprocating models use a piston to drive air from the atmosphere into an air storage tank. Think of this like the air pumps used to inflate volleyballs except that a motor is driving the piston rather than someone’s hand. Most portable units will usually have just one piston. Models can also have more than one piston. However, the piston count is generally limited to two for all but the most demanding commercial and industrial applications.

This process can have multiple stages. If an air compressor has but one piston, then the process has but one stage. Note that featuring multiple pistons doesn’t necessarily indicate multiple stages. There can, for instance, be two air storage tanks with an independent piston assigned to each. Multistage is a specific configuration in which one piston is used to drive air from the atmosphere into a valve. A second piston then drives air from the valve into a tank. The concept of filling the tank and creating pressure remains the same, but the multistage model is able to create more pressure and more air volume faster.

Power Source and Lubrication

In addition to one or more reciprocating pistons, a portable air compressor will have a connecting rod, crankshaft, cylinder and valve head. The piston operation has to be powered, and there are two fundamental ways to do that: electric motors and fuel-based engines. Motors require electricity, such as connection to a wall outlet or a battery. Engines require fuel, such as gasoline or diesel. The power source does change the operation of the machine to some degree in that electric units have an auto feature that lets them turn on and off as needed. Engines, on other hand, require manual starting and stopping.

A piston generates a lot of heat due to friction. This friction needs to be offset in order to keep temperatures low and save wear on the parts involved. The conventional way to do this is through the use of compressor oil. Models that use such oil are categorized as oil-lubricated. An alternative to this is oil-free, which is sometimes called oil-less. These models have a cylinder that is coated with Teflon to reduce friction. This approach is less expensive for the consumer in the short-term but not necessarily the long-term.

Storage Tank, Volume and Pressure

image of portable air tank Air compression is a process through which air volume is decreased and pressure is increased. This is why the balance between PSI, SCFM, tank size and so forth is so important. The purpose of the air tank is to store air at a specific pressure until that air is required. The piston drives air into the tank. As more air is delivered to the tank, the pressure intensifies, and a sensor is used to gauge the current pressure.

While such a machine is in use, achieving the ideal pressure, which is dictated by dialing in the desired PSI, is an ongoing process. Consider a scenario in which a homeowner is using a nail gun to put up a fence. Each time a nail is fired into a board, air is removed from the tank. Therefore, the pressure changes. The piston then activates to deliver more air and bring the tank back to the target PSI. This is where the auto feature of an electric model comes into play since it can conserve energy during this process.

Adjusting Pressure and Engine Temperature

image of 225 PSI High Performance Crew Electric Portable Air CompressorPortable air compressors have a cut-out pressure, which is the default pressure for the machine, but can support a pressure a range above that default. Most units have a gauge that indicates PSI and SCFM as well as a dial that lets the user set the desired PSI. The purpose of the dial is that not all applications require the same PSI. That nail gun mentioned earlier certainly has greater demands than will be require when reaching a desired PSI for automobile tires, for instance. In fact, an air compressor is at its most efficient when you use as little pressure as needed.

As mentioned earlier, the piston action generates a lot of friction and therefore heat. This heat is exacerbated by the heat that the engine or motor itself generates. Compressors designed for pneumatic tools and more demanding jobs will often have an air cooling system in place to help alleviate that heat buildup. Most models have thermal protection as well. This safety precaution triggers when the heat is too high and shuts the machine off to protect it. Although not common on modern machines, if a compressor lacks such safety features, then engine temperature has to be monitored by the user as part of operation.

Use and Accessories

A portable air compressor has to be started. With an electric model, this is generally as simple as plugging it in and flipping a switch. Compressors with engines will feature a pull-start or other mechanism. These machines don’t store air while off, so once the machine starts, it will begin to fill the tank. Once it reaches the cut-out pressure, it will stop. The machine is now safe to use. A hose should already be connected. Set the PSI to the desired level, and the air is now available for whatever purpose.

An air compressor without an attachment simply blows air. To get the most out of these machines, attachments are required, and attachments are added via coupler fittings. These fittings can be as simple as a tire inflator attachment or an air tip that makes it easier to perform detailed cleaning.

There’s also a wide range of fittings that let users connect various tools. An air compressor at its most powerful not when inflating something but rather when providing the energy necessary for air ratchets and the like.

Which portable air compressors are best?

Best is a matter of perspective and depends greatly on how a person intends to use the machine. The person who’ll use pneumatic tools needs a more powerful machine than the person who’ll just fill automobile tires and inner tubes. It’s certainly best to choose a portable air compressor manufactured by a leading, established brand that stands behind its work with a strong warranty and other guarantees. Choosing an ASME-certified product is also a good idea. Such approval means that the air compressor has met the standards of the American Society of Mechanical Engineers.

One of the major determinations a consumer will have to make in deciding which model is best for them is oil-lubricated versus oil-free. Oil-free or oil-less machines have a Teflon coating rather than lubrication. These machines are less expensive and targeted at casual use. Oil-free is generally regarded as inferior. However, it’s worth noting that oil-less compressor design has come a long way in the last decade or so. Oil-lubricated pumps require more maintenance since the user has to top them off and even change the oil periodically. Nevertheless, the lubrication increases life expectancy considerably, and these machines can last 15 years or more.

Electric versus Fuel-Based

There are two fundamental types of air compressors: those with an electric motor and those with an engine that requires fuel. The electric variety is quite common for home use due to the convenience. Most models are corded.

They have an integrated cord, which has a plug at the end, and that plug fits into any standard wall outlet. Note that these appliances are generally not designed to supported extension cords. There are also options that use rechargeable batteries, but these may be inconvenient, and it’s often necessary for the user to have multiple charged batteries on hand. Hybrid models support batteries but only access the battery charge when the appliance isn’t connected to an outlet.

Portable air compressors with engines tend to be much more powerful. They can deliver more horsepower after all. The downside to an engine is that it creates fumes. That means ventilation is required for indoor use, and the machine often needs an attachment to direct the fumes. Engines that use gas are most common, but there also engines that use diesel instead. Diesel tends to allow for a lower total cost of ownership, but the fumes produced are even thicker than those created with gas. It’s also worth noting that the added hp provided by fuel is often overkill for residential applications.

PSI, SCFM and Tank Size

There are various styles as well, including pancake, hot dog, vertical and so on. However, what’s best may more likely come down to factors like PSI and SCFM as well as HP. There’s a correlation between all three of these characteristics. The average consumer may want to focus on PSI, which stands for pounds per square inch and indicates how much pressure an appliance can produce, but certain tools may demand a specific SCFM or even HP level. SCFM stands for standard cubic feet per minute and indicates the air volume that the product can provide.

Another crucial consideration is tank size. Inexpensive pancake units may only have a six-gallon tank. That may be best for the person who just tops off their tires from time to time, but it certainly won’t be enough for the user who wants to operate the machine uninterrupted for any length of time.

A big tank lets the user work longer but also have access to a stronger airflow. When using pneumatic tools, experts often recommend a 30-gallon tank at minimum and a 60-gallon tank ideally.

Tank Orientation and Multistage Operation

Tank orientation may not be as crucial a consideration as tank size, but it can be important nonetheless. Vertical tanks, for instance, are less stable but take up a lot less space. Pancake and hot dog models are very stable and easy to move around. A twin-stack model is like a hot dog compressor, but it stacks two air storage tanks, which can mean the different between 30 and 60 gallons in a relatively compact form factor.

Something else consumers should consider is whether they want a standard single-stage portable air compressor or a multistage model. A single-stage unit uses a piston to drive air from the atmosphere into the tank.

As more air is added, the tank becomes more pressurized. A single-stage unit may have multiple pistons, but they work independently. With a two-stage setup, the first piston drives air into a check valve. The second piston then drives that air into the tank. This two-stage process allows for more air at a great pressure faster.

Accessories and Safety Features

image of Oil Free Portable Electric Air CompressorA common safety feature on portable air compressors is thermal protection. This is a switch coupled with a sensor. The sensor monitors engine or motor temperature. If the temperature goes beyond the upper threshold, the switch is triggered and the machine shuts off. This prevents an engine from overheating and being damaged. Users are advised to test the thermal protection on a regular basis so that they know it’s working. Without such thermal protection, the user has to monitor engine heat manually, and that can be quite the inconvenience during an extended task.

Noise is another consideration. It may not matter for occasional use but could be a big consideration for extended use around the home or on any site where a noise ordinance is enforced. DIYers who’ll use multiple pneumatic tools may want to consider multiple couplers. This allows for connection of multiple tools simultaneously, which avoids the inconvenience of having to swap back and forth. Other useful accessories include work gloves, padded handles, air tips and various other attachments. Some models offer starter attachment kits, and these are available separately as well.

What are portable air compressors used for?

A portable air compressor provides air. More importantly, it provides pressurized air, which means that the air is released in a forceful manner. That can be used to power something via kinetic energy, but users can also target that air jet in a very precise manner. The fact that these particular appliances are portable also implies convenience. Users can bring them to the task whether that means across the garage or in the RV. The DIYer isn’t limited by the length of the hose plus the power cord, if applicable, and these units are generally compact and lightweight.

Among the most practical and common uses for an air compressor is to fill things with air. Anything that can hold air and has a seal can be filled. However, it’s important to note that there’s a difference between a compressor, an air pump and an inflator. A compressor has an air pump, but the term air pump can also refer to the handheld variety used to pump bicycle tires and footballs. Inflators are generally handheld but differ from a hand pump in that they’re powered and differ from a compressor in that there’s no storage tank to collect air.

Automobile Tires and Inner Tubes

Perhaps the greatest argument for owning a portable air compressor for anyone who owns a vehicle is being able to fill their vehicle tires as needed. Tires will lose air over time as that air expands and contracts. It’s recommended to check the tires on a vehicle once a month. It’s also recommended to test the air pressure when the tire is cold, which can be a challenge if a person has to drive down to the local gas station in order to fill those tires. With this tool on hand, a vehicle owner just has to remove the valve caps, test the air pressure with a gauge and fill as needed.

Automobile tires don’t have inner tubes, but there are many items to be found around a home that do. If children have bikes or the adults use bicycles for exercise or trailing, then these machines make tire maintenance a breeze. It’s even possible to fill balloons for a birthday or other celebration, and parents will love the convenience with which they can fill basketballs, footballs, soccer balls and more. Parents can also fill bouncy castles, inflatable pools, pool toys and so forth.

Detail-Oriented Cleaning

Perhaps the most underappreciated aspect of owning a portable air compressor is being able to clean items that are otherwise difficult to clean. The only caveat is that the thing being cleaned must be able to withstand the force of the air at the lowest PSI that a particular machine supports. Not only can the air jet eliminate caked-on grime and other particles, but it can really get into those nooks and crannies. This is particularly useful in those scenarios where water and other cleaning methods just aren’t practical.

An air compressor is often used alongside a vacuum when auto detailing, and it’s even possible to clean out electronics and other items that can collect dust. Computers users can even save a lot on canned air and avoid buying a separate air duster by using a compressor instead. However, it’s important to point out that pound per square inch is a serious consideration when dealing with electronic components. Additionally, water vapor in the air can damage electronic components, so it’s necessary that the machine have a moisture trap and that the trap be properly cleaned and maintained.

Painting and Sanding

Another area where these machines can come in hand is painting. Whether a homeowner is repainting his or her entire house or refinishing a set of handcrafted kitchen chairs, spraying rather than brushing and rolling makes these tasks more cost- and time-efficient. A standalone paint sprayer is an option, but at that cost, that’s simply a luxury that most people don’t have. If, on the other hand, a person already owns an air compressor, then all that’s required to have a paint sprayer on hand is an air-driven paint gun.

This usefulness isn’t limited to just the final finish but all manner of surface preparation as well. If there’s any wood or other surfaces that have to be sanded down before priming and/or a paint application, then these machines can ease that process as well. Simply attach an air-driven sander and cut the amount of effort and time required by a significant amount. By setting the PSI appropriately, the sander can even ensure that the sanding isn’t so powerful that it damages the surface.

Pneumatic Tools

Paint sprayers and sanders aren’t the only options when it comes to pneumatic tools. Pneumatic tools are also called air tools, air-driven tools, air-powered tools and so forth. Rather than being powered by a battery or connected to an electrical outlet, these tools are driven by the kinetic energy created from the pressurized air.

Not only are these tools often more convenient than electric tools but often more powerful as well. An air ratchet, for instance, can loosen nuts that are almost impossible to loosen otherwise because they’ve been stripped or rusted.

There are many types of pneumatic tools that a DIYer can purchase to go along with his or her portable air compressor: hammers, drills, impact wrenches, nail guns, screwdrivers and much more. The nice thing about pneumatic tools is that they’re always ready to go when you need them. During any downtime, the compressor refills the tank. In addition, with multiple couplers, the DIYer can have multiple tools attached simultaneously, which is really convenient, for instance, when going back and forth between a drill and a screwdriver. Note that air-driven tools will generally have specific requirements for PSI, SCFM and HP.

Where should a portable air compressor be purchased?

image of portable air compressorConsumers shopping for portable air compressors have a number of options. Locally, there are mom-and-pop hardware shops, big hardware chains, larger retailers who cater to DIYers and even large retailers who have garden and home improvement departments. Consumers also have the option to buy online. While many shoppers may not think of the Internet first when purchasing large appliances, this practice is becoming increasingly more common. Market experts expect the trend to continue, and it won’t be long before most homeowners are buying major appliances online rather than locally.

There are many greater reasons why Web-based retailers are attracting more and more customers. This includes enticing buyers to make purchases that were once not considered feasible online. In addition to home and DIY appliances, people are using the Internet to buy clothes, food, televisions, automobiles and much more. We’re going to explore all of the factors leading to these increased sales in greater detail. These include selection, convenience, price, personalized customer service and much more.

Selection and Convenience

One of the challenges facing the homeowner or small business that wants to purchase a portable air compressor locally is choice. There are many leading manufacturers offering a lot of different models and features. The problem is that local retailers don’t move such appliances in great volume. They have to maximize available storage space. That means that local retailers tend to limit their stock to models that are popular in the region and most likely to sell. What’s popular isn’t necessarily best for any particular consumer. Online, the buyer instead has access to all makes, models and configurations.

It’s also a matter of convenience and time-savings. Locally, a shopper may have to spend hours going from one location to another. Online, buyers have the option to shop after local stores have closed and even in the middle of the night if that’s what they prefer. All of the data and other information that a shopper may need is consolidated and available at his or her fingertips. This makes research much easier. Call up owner’s manuals with ease and find experts on a particular model or feature with just a mouse click or two.

Price and Manufacturer Support

Even if a particular model that a shopper wants is available down the street, chances are that product will be available at a cheaper price from multiple retailers online. There just isn’t much margin in such products and so the local shops only have so much flexibility. Online shops, on the other hand, have much less overhead. The cost of a virtual storefront is just dramatically less than an actual storefront, and those reduced fixed costs can be passed on to the consumer without taking a hit to profits. Drop shipping can even reduce costs further because manufacturers can offer products for less.

It’s also important to point out that manufacturers that stand behind their products do so whether a consumer purchases locally or online. It doesn’t matter to the manufacturer. The warranty provided with a particular product will be the same whether that item was bought online or downtown.

If a brand offers an extended warranty, that same extension can be claimed through the online retailer or the manufacturer website. All advertised guarantees are the same as well. Additionally, if a consumer needs manufacturer support, such as technical assistance or an RMA, that process is the same as well.

Delivery, Returns and Exchanges

A portable air compressor bought locally may or may not have to be delivered depending on the buyer. These products generally weigh between 30 to 60 pounds. Even if not required, delivery is a matter of convenience. Unfortunately, delivery from a local shop is generally going to cost more and thus increase the upfront and total cost of ownership. With large purchases, most online retailers ship free and can have an air compressor to a customer’s doorstep in just two days and sometimes sooner.

Returns and exchanges are a common concern among consumers who aren’t yet used to making purchases online. The good news is that Internet-based retailers have recognized the services that they need to provide in order to be competitive. Many of the big online retailers will even allow return of a non-defective product with no questions asked and without a restocking fee. That takes a lot of pressure off the consumer. Exchanges are also supported, and many e-shops offer 30 days or more to make a decision. Another nice touch is the exchange of a defective product. Many companies will ship a new product in advance of receiving the return so that the customer will have a working item as soon as possible.

Budgeting and Customer Service

When making a large purchase like a portable air compressor, a budget is often involved. That budget not only covers the main product but any supplies and accessories that are needed as well. This can be a lot to deal with while walking around a shop and perhaps visiting various stores. Online, there’s a lot less pressure. The website will even tally your total shopping cart and can add taxes and other fees. Consumers also don’t need to worry about high-pressure or a salesperson not available when you need him or her. Website users can access live chat to speak with an expert on demand, and the process is very low pressure since the shopper can leave and come back to the chat as needed.

Where should an air compressor be purchased? It’s difficult not to recommend the Internet. The allure of local shopping is certainly understandable for the person who hasn’t yet acclimated to online shopping, but the advantaged to e-commerce are just too great. Consumers pay less and get what they need with a lot less time spent.

How do you repair a portable air compressor?

image of Fixing a Porter Cable C2002 RegulatorThe first step in fixing a portable air compressor is determining why it has failed or is malfunctioning. This is the troubleshooting phase. It often helps to disconnect the appliance, disassemble accessories and major components and then approach the machine as if it had just been removed from the box. Clean it, perform basic maintenance and then follow the steps to connect everything and use the product for the first time. If that does not alleviate the issue, the manual provided with the product by the manufacturer will often have a troubleshooting section that the user can follow on a step-by-step basis. Working through these steps will often identify the issue.

Some of the common issues users may encounter include the machine not turning on, pressure not building up and air not blowing from the hose. How to repair a portable air compressor will depend on the specifics of the problem and in some cases may require a professional technician. With that in mind, we’ll look at some of the most common troubles as well as how DIYers can take care of those problems on their own rather than seeking assistance elsewhere.

Restoring Power

A common problem that occurs with electric models is that the user flips the on/off switch and then nothing happens. Check to make sure that the cord is firmly attached to a wall outlet. If the power cord is modular rather than hardwired, check the connection at the machine as well. Try the switch again. If nothing happens, then locate the Reset button, which will usually be located on the side of the motor near wear the power cord connects. It will usually be red or black, and pressing this button will reset the internal circuit breaker. In most cases, this will restore power.

If this does not work, then trace the power cord to ensure that all connections are snug. Try a different wall outlet. Locate the circuit breaker panel at the home or site and ensure that the breaker for that particular outlet or the entire zone has not been tripped. If it has, flip it from the Off to the On position. Try a radio or other small device in the outlet. If it works, then there is a problem with the electrical system of the appliance and a professional repair person will generally be required.

Replacing an Unloader Valve

Another common issue with such machines is that they will start up just fine but eventually stall. On subsequent attempts, the machine will make a loud humming noise. When this happens, it is a clear sign that the unloader valve has gone bad. This part is common to piston-based compressors, and it exists to blow off any pressure inside the discharge pipe when the compressor stops. If the valve isn’t working properly, then whenever the compressor starts back up, the pipe will still be under pressure, and the motor will not be strong enough.

The good news is that this is a relatively inexpensive part and the installation is simple as well. The unloader valve is usually part of the pressure switch assembly, and DIYers can either purchase a new assembly or buy the valve itself, which will be cheaper with the trade-off that the install will be a little more involved. Unplug the machine. Open the drain valve to unpressurize the tank. Remove attachments from the pressure switch, such as the regulator and gauge. At this point, remove the old valve and replace it, or remove the wires from the old assembly and connect the new assembly.

Building Pressure

A portable air compressor will sometimes be unable to build pressure in the tank. Turn the machine off. Detach all hoses, tools and ancillary attachments. Prepare a spray bottle by mixing water and dish soap.

This mixture will be used to identify air leaks near fittings by the bubbles they create. Locate the air outlet, which will generally have an attached pull ring along with a small valve that may be plastic or metal. Spray all of the fittings with the prepared mixture, and then, release the pressure from the tank by pulling the air release valve.

Use a wrench to remove all fittings that have active bubbling present. This require counterclockwise action. Once removed, wrap the threads of those fittings using Teflon-based plumber’s tape. Thread those fittings back into the machine. Tighten by hand with a wrench. Test the compressor again using the soapy water. If there are any fittings that still leak, then those fittings will need to be replaced. Finally, check the bleed valve at the bottom of the tank. Charge the compressor. Loosen the valve and allow the air to blow out all condensation. When the escaping air is dry, tighten the valve.

Replacing a Check Valve in a Portable Air Compressor

A check valve prevents air from flowing back to an air pump. This part will wear over time and is a common item that requires replacement. Users will know that it’s time to replace the valve because the machine will operate fine until the tank has filled, but once that happens, the motor will no longer be able to start. Note that these valves can be rebuilt; however, this part is relatively inexpensive for most residential-grade models and thus the time expense of rebuilding usually isn’t worth it.

Unplug the machine and drain the air tank. Disconnect the pressure switch tube as well as the outlet pressure tube. Using a wrench, unscrew the check valve and remove it from the tank. Install the new check valve. Replace the outlet and switch tubes. Clean the work area. Plug the device into a wall outlet. Let the tank pressurize. Test to ensure that the machine can now run once the tank has filled.

Disclosure: Some of the links in this post are 'affiliate links.' This means if you click on the link and purchase the item, I will receive an affiliate commission.
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