How to Choose an Air Compressor, According to Science
Buying an air compressor, for the first time, can be challenging in many ways. There is a lot going on behind this power tool that offers faster and more efficient performance. Before we get to know about the details of an air compressor then, let’s understand how it works. How do air compressors work?
An air compressor turns electrical energy into powerful kinetic energy. It is a lightweight and portable tool for powering other compact and handy tools such as impact wrenches, sanders, drills, and such. The purpose of an air compressor lies in factories, garages, and even in homes. For appliances that need a constant supply of a higher volume of air, an air compressor is very useful.
For professionals completing a job, operating other handy tools with the help of an air compressor comes with many benefits. It is not all about an air compressor’s quick and efficient deliverance.
The following factors will give you a clear understanding of how air compressors work. With this knowledge you can stay rest assured when choosing the best air compressor for your needs.
1. Piston or Portable Air Compressors - Which is Best?
The most basic types of air compressors are piston and portable. The former depends on a functioning motor, which promotes air pressure during the depletion process. This means it relies on the air pressure increases with an increase in usage. It comes with a tank that keeps it grounded in one place for as long as you use it.
Portable air compressors come without tanks; they carry out the same function of a piston air compressor, but are portable enough to move around the house.
The air compressed in a piston compressor’s tank requires heavy-duty maintenance. And when compared to portable air compressors, they are a better fit for high-end, commercial jobs than menial work.
The advantage of portable compressors is that they deliver continuous air pressure, with minimal footprint. This makes them more suited to light household use.
You will find two sub-types of a piston air compressor: single-stage and dual- or two-stage. Compressors with single-stage functionality exhaust only a single piston for air compression. And they go as high as 150 psi.
Two-stage air compressors make complete use of 2 pistons, delivering constant air pressure at 200 psi. A single-stage compressor is perfect for small to bigger tasks, but for home use. Meanwhile, two-stage compressors suit commercial jobs that require continuous air pressure.
For a single-stage air compressor, the motor draws in air and compresses it with air pressure in every rotation. So it requires a higher CFM rating than a dual-stage compressor.
For a dual-stage air compressor, the first step sucks the air in and compresses it immediately. This is followed by the compressed air being piped with the help of an intercooler to be released in its final stage.
In hindsight, a two-stage air compressor is more energy-efficient and effective than a single-stage unit. This is because in a two-stage compressor the higher air pressures are cooled in-between stages for better air pressure release.
If you are using a portable air compressor, it has certain applications such as for powering pneumatic tools, pumps, pipes, and common home-use equipment. You can use one to increase efficiency and speed, in lesser time, as compared to using a single-piston air compressor.
At the end of the day, using any one kind is a matter of convenience and personal preference. Both types are easy to use with practical usability.
As for the price, buying a piston air compressor is more expensive than a portable one. The main reason being that a piston air compressor comes with an air pressure storage tank and a portable on is mostly handheld.
Several pneumatic tools require more or less compressed air. This factors in the cubic feet per minute measure of an air compressor. When sizing an air compressor in terms of functionality, you can determine the ideal type based on its CFM range, and not the horsepower range. This saves time, space, and money.
After considering all these factors, it is safe to say that you get what you pay for when choosing an air compressor. Based on the cubic feet per minute, maximum air pressure, motor settings, and storage tank size of an air compressor, it is easier to find the right fit for a unit.
You need to be able to determine whether you can roll or push or pull the air compressor easily. It is true that there are portable and compact air compressors like the best pancake compressor, but they might not possess the features you are looking for. If you are investing in a model for longer use, buying a higher capacity compressor is more appropriate.
Finally, you need to ask yourself whether your compact air compressor will be able to power a nail gun as effectively as fill tires in your garage?
2. Don’t Forget The CFM Measurement
To keep things going, considering CFM or Cubic Feet per Minute is equally important. It is the final volumetric flow measure of an air compressor. But here’s the catch, determining the CFM of any unit depends on its psi range.
When you are calculating two units’ CFM measurements, it is important that both possess the same psi level. If they are different, your calculation will be wrong. To make things easy, Here is a simple run-through for taking the CFM measurement of an air compressor.
Check the standard cubic feet per minute measure of an air compressor. Note that SCFM is generally measured as 14.5 PSIA, at 68 degrees Fahrenheit, and 0% humidity level. Just in case this is too complicated for you, use only the CFM measure of various air compressors. But all should remain the same.
Once you have the SCFM measure of each tool, add up the numbers and increase by 30%. This is so you have plenty of room to work with. The final calculation will give you an exact measure, the number you need to work on and check for when choosing an air compressor. You might not find an air compressor of the exact measurement, but it is important to get as close to the number as possible.
In other words, the CFM range can determine how much air pressure the air compressor delivers, per minute. This rating is important because it lets you know the air output for proper performance of any unit.
So how can you use the CFM to power multiple tools at one time? This we shall determine on a range of small to large tools. If you are operating multiple larger tools at one time, you will need more CFM ratings. On the other hand, for smaller pneumatic tools, the compression operation varies based on its psi ratings.
But the best and most convenient way to make the most of your air compression is by its SCFM ratings. Because here you calculate all the necessary details, including the psi ratings back to its standard settings. So you can use the air compressor for your desired purpose without compromising on quality.
The last thing I woud like to mention regarding CFM is comparing different ratings of different units. Looking for other CFM-related factors such as temperature, altitude, and humidity is important. This helps to look at different air volumes and pressures.
Other factors such as heat dissipation, atmospheric pressure, and friction do not fall under CFM ratings. These variables can be taken into consideration when looking at individual features of an air compressor. This differs from unit to unit.
3. How Much Space Does It Need?
Every machine on the market comes in either a large and more powerful design or a small and portable version. That’s the way technology works, isn’t it? No wonder we, as humans, are so spoiled for choice!
Getting back to the size of the air compressor, it all depends on what you need the most. Are you going to lift the fixture off the floor or roll it? In any case, portability always brings more convenience to the table.
But if you are absolutely sure that the air compressor is going to rest in peace in a single corner of your garage, then the situation doesn’t demand portability. Instead, what you need is a comparatively longer hose. And this particular feature is only present in high capacity compressors.
Before I discuss the tank size, let me tell you something crucial about portability. The factor is not concerned with just the weight of the machine. Even a lightweight air compressor might be difficult to carry if it is too wide in shape. So don’t forget to take the shape of the unit into consideration as well. Slim compressors are easy and convenient to carry with you. But their broader-designed counterparts aren’t.
Now it is time to discuss the size of the tank. In the case of tank-mounted units, you have to decide how large the tank would be, and this depends on the use of the air compressor. For example, if you need a compressor for short-lived tasks, a small tank size might be an ideal choice for you. On the other hand, bigger tanks are more suitable for heavy-duty purposes.
The longer the process, the higher the gallons, am I right? And it works the other way around for shorter or lighter tasks.
Since the purpose of the tank size is set into place, I can move on to talking about efficiency. What I mean to say is that the size of an air compressor’s tank helps in determining the amount of time the air tools run without the unit turning back on.
Tanks come in gallons, right? So you get size options ranging from as small as one gallon to as large as 80 gallons.
When working with air tools or equipment that demands high air volume for continued use, nothing beats the efficiency of the larger-sized tank. Alternatively, intermittent use of the tools doesn’t require an air compressor with a big tank. A small size is more than enough for such jobs.
Here’s something you ought to know about large tanks. These feature the useful compressor pump with a SCFM tool requirement that exceeds the normal value. Such a composition allows the unit to cool down between cycles.
Tools and equipment that demand a quick, short round of air tend to exhaust the tank relatively slower. So it is safe for me to say that for such purposes, anything between two and six gallons is perfect for the job. This means finish nailers and pneumatic brad don’t demand the use of large air compression tanks.
4. Checking The Pump Settings
In this category, there are two basic configurations. Reciprocating air compressors have single stage and two stage pumps. These two are primary settings, so let’s discuss them before I talk about the other secondary pump types.
Air compressors with the single stage pump setting draw in and compress the air in one piston stroke. This means that the air reaches the final pressure with a single stroke. These types of units have the ability to achieve pressure as high as 150 psi.
Normally, the single stage machine has a comparatively higher CFM value than its two-stage counterpart. And why do you think that is? It is because each cylinder of the unit not only draws in the air but also compresses it with every rotation.
By now, I am sure you understand the difference between the two different pump settings. With a two-stage machine, the air is compressed in not one, but two steps. During the initial stage, the unit draws in the air and compresses it down to the intermediate pressure. Soon after, this air travels through the intercooler to get ready for the second or final stage.
You should know that the two-stage pump setting is an ideal choice for pressures that reach 200 psi. It is considered to be more efficient than the single stage pump when using higher pressures. And that is because in the case of the former, the air goes through the process of cooling between the first and second stages.
Now that you know the primary settings, it is time to discuss the secondary ones. These are oil-free and oil-lubricated air compressors. Roll cages, air-cooling systems, and thermal overload switch are the kinds of features that protect both the machine and you from accidents or damage while working.
To make it easier for you to understand the different pump types, I have listed all of them below.
Oil-free air compressors: The oil-free units use unique piston rings built with materials that are similar to those required for manufacturing non-stick cooking pans. These rings lubricate the machine’s cylinder.
Due to the absence of oil, these types of compressors are relatively lighter and smaller than their oil-lubricated kin. This means they are suitable for home and work applications as the portability factor comes into play here.
Oil-lubricated air compressors: The engine of a lawn mower or car requires oil to function, right? This also applies to certain kinds of air compressors. What the oil does is lubricate the unit’s moving parts present in its pump. It also contributes to preventing excessive wear.
Oil-lubricated air compressors are heavier and larger than the oil-free version, and they require regular maintenance. If you don’t change and monitor the oil, it can lead to premature failure.
Single stage air compressors: More often than not, these come with a single cylinder that compresses air using the same output strength.
Two stage air compressors: The two stage units have two cylinders. The first one feeds air and prepares it to enter the second cylinder; it is in the second cylinder that the process of air compression takes place.
Two stage compressors have tank pressure that reaches 200 psi. They have the upper hand when compared to the single stage machines. That is because two stage pump settings store more air, which allows a longer tool-working time. Such a characteristic is suitable for heavy-duty tasks like continued tool operation when working in any auto shop.
5. What Kind Of Features Does It Offer?
If you want to get an air compressor that meets all your needs and requirements, then you have to know all about its features. This way you have a better understanding of what you might require to make your job easier.
Thermal protection: This component comes in the form of a thermal overload switch and is responsible for stopping the motor. The switch turns off the motor automatically when it overheats.
So you get an increased tool life, don’t you? In fact, thermal protection prevents the unit from damage due to overloads. If you wish to safeguard your investments, please make sure that you get an air compressor with the thermal overload switch.
Oil-free pump: When the compressor has an oil-free designed pump, what does that mean? It reduces the cost and effort of maintenance. Such a composition also eliminates the possibility of the oil and compressed air mixing together.
Multiple couplers: A unit with multiple couplers gives you the fantastic opportunity to handle many tasks, without having to connect and disconnect the tools to achieve the desired results.
Belt-drive system: As opposed to direct-drive systems, the belt-drive versions offer a quiet operation. This is why the majority of people opt for belt-drive instead of direct-drive.
Air-cooling system: This is pretty much self-explanatory, isn’t it? With an air-cooling feature, your pumping machinery remains cool throughout the procedure. It also contributes to extending the shelf life of the motor.
Adjustable exhaust: Such an element directs the exhaust of the air compressor away from the working area. And we all know how beneficial that is.
Roll cage: The roll cage is responsible for protecting the unit from severe damage on your job site. Compressors are often subjected to being battered or crushed. But the chances of accidents like this taking place are highly unlikely if you buy an air compressor with a roll cage.
ASME certification: It is always a better idea to look for a certified model as that indicates the use of high-quality craftsmanship and materials. You can look for the certification label on the unit’s tank. This label states that the machine lives up to the standards and requirements of ASME (American Society of Mechanical Engineers)
Cord wrap: Many air compressor manufacturing companies provide tons of convenience when it comes to wrapping up the invaluable power cord. Easy carrying and storage are essential, adding more comfort to the whole experience.
Ball valve drain: When water is subjected to condensation in the tank, it causes pinhole leaks and rusting. To prevent such a tragedy from taking place, it is important to drain the compressor’s tank regularly.
All the tanks of air compressors come with drains, right? But the type of drain matters. The drain cock design is slightly complicated and requires the use of pliers. On the other hand, the ball valve drain offers more comfort and convenience when it comes to usability.
Other accessories: These include inflation components, hoses, blow guns, and nailers. What they do is add more value to the purchase.
Now that the technicalities are all settled, the responsibility to choose the best air compressor falls on your shoulders. It is always good to exceed your own expectations when it comes to buying large appliances. But with the right kind of information by your side, buying a stable and energy-efficient appliance that will last for years isn’t undemanding.
This handy guide will keep you well-informed about the way an air compressor functions, its best features and significant benefits. You will be able to operate an air compressor more effectively after you are done with this guide. And if that is not enough, I would advise you to print it out and ask a local shop owner some technical questions to get the right model.
The most important consideration for choosing air compressors is the performance ratings. Is the compressor energy-efficient? Can it handle multiple pneumatic tools at once? And is it durable?
While there are single and double stage compressors, finding your ideal unit will take time. And sorting your budget out to fit in some extra features such as a roll cage, thermal switch, durable cover, and a cooling system isn’t a bad idea.
Investing in an air compressor for your home projects will cost you for years to come. So choosing wisely and with proper know-how is essential. You won’t believe how modern air compressors are finding their true calling in more and more workshops and home garages. They are fit to handle all sorts of tasks from power tools to inflating toys. You can buy your ideal type right away from a local home centre, for the right cost!
Text: Jen Miller at Jenreviews
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