Air Compressor Types – Ultimate Guide
- Mar 17, 2023
The air compressor is one of the most crucial tools in the construction or rental industries. These machines power a variety of other tools, from air wrenches to nail guns to air sprayers and paint guns. However, not every type of compressor is suitable for every end use. Therefore, effective air compressor use depends on choosing the right type of machine for the job.
Below are seven common types of compressors and their ideal applications.
Rotary Screw Compressors
Air compressors fall into two broad categories based on how they operate: positive displacement and dynamic. Positive displacement options, such as screw compressors, provide a constant flow regardless of outlet pressure. In a rotary screw compressor, this is accomplished by compressing the air in a sealed chamber by a pair of counter-rotating screws.
One of the biggest advantages of a rotary screw compressor is that it can run continuously when you need it. They are also very durable, often a few years or longer than other types. As such, they are ideal for prolonged heavy-duty use, such as powering jackhammers or sandblasting operations.
Screw compressors’ primary drawbacks are their cost and upkeep demands. They typically cost more and demand more attention than other positive displacement options, so smaller operations may require alternatives.
Reciprocating Compressors
Another favourable displacement option is a reciprocating or piston compressor. As the name suggests, they use pistons to compress and displace the air in their chambers. These are among the most powerful home compressors, making them a popular choice.
While rotary screw compressors can generate more power overall, reciprocating compressors can generate a lot of power with low energy consumption. They are also more compact than rotary screw machines, making them more suitable for shorter, more flexible jobs. This low energy consumption and portability make piston compressors suitable for powering hand tools.
However, these compressors generate more heat and noise than other piston machines, so they are unsuitable for long-term continuous use. For many construction jobs, this is not a problem, but they may not be the right choice for heavy machinery.
Scroll Compressors
The third major type of air compressor is the scroll compressor. These machines use two circular scrolls, one stationary and the other rotating inside, to compress the air. This design reduces moving parts and vibration, resulting in a longer lifespan.
Scroll compressors produce the cleanest air according to ISO standards. Therefore, construction jobs or companies that must adhere to higher environmental standards may wish to use these machines. They are also versatile and operate at various intensity levels.
While quiet and easy to maintain, scroll compressors do not produce maximum power. Heavy tools and machinery may require a different compressor, but more passive applications are ideal for these applications.
Centrifugal compressors
Unlike the first three entries on this list, centrifugal compressors are dynamic. This means they draw in air from the outside rather than using an enclosed air reserve. In a centrifuge, this is thanks to a rotor called an impeller that spins inside a cylinder to force air in.
Some centrifuges use multiple stages to increase the pressure and provide more power. Multi-stage compressors can deliver extraordinary horsepower, making them ideal for powering heavy equipment. Like rotary screw compressors, these machines can also run continuously for longer jobs.
Centrifugal compressors are also very affordable compared to similar horsepower alternatives. However, their reliance on fast-moving parts makes them more prone to problems like stalling or choking.
Axial compressors
Axial compressors are another dynamic machine. These do not use an impeller but multiple rows of fan blades within the shaft. Higher pressure is produced as a result of the air’s continuously increasing velocity as it moves through each row.
These compressors are generally smaller, lighter, and operate at higher speeds than centrifugal compressors. This enables them to provide constant flow rates at large volumes, but usually at lower pressures than alternatives. Due to their consistency and energy efficiency, you will often find them in pumping applications.
Axial compressors are a crucial part of jet engine design, but in buildings, you’ll find them used for pumping or generating electricity. But these are generally rare on construction sites due to the high cost.
Oil-flooded compressors
Another way to classify compressor types is based on their lubrication into two categories: oil-flooded and oil-free. As the name suggests, oil-filled compressors have lubrication in their inner workings. More specifically, they have closed oil-lubricated compression chambers.
Rotary screws and reciprocating compressors are often oil-filled. The constant presence of lubrication means that oil-flooded compressors are generally more durable. However, they also run the risk of oozing lubricating fluid, which can contaminate the compressed air.
The FDA requires using oil-free air in certain industries, so construction teams adhering to higher cleanliness and safety standards should avoid oil-filled compressors. However, these are safe and cost-effective options for most low-power construction equipment.
Oil-Free Compressors
In contrast, oil-free air compressors do not have any oil in the compression chamber. Instead, they have built-in, long-lasting replacement lubrication on their moving parts. Therefore, these can produce air without any trace of potentially dangerous oils.
Centrifugal compressors are generally oil-free, and some oil-free rotary screws and reciprocating compressors also exist. These can be more expensive, but they produce cleaner air and generally work at lower temperatures and noise levels. These advantages make it ideal for construction in busy areas or environmentally friendly construction sites. Oil-free compressors are also better for continuous operation as they require less maintenance. However, they may require extra work to last a long time.
Fixed and variable air compressors
The main difference between an air compressor with a fixed speed system and an air compressor with a variable speed system is how the motor gets its power. The compression elements of all machines are basically the same, but the way the motor operates affects the availability, efficiency, and longevity of the machine.
Variable speed compressors, often referred to as VSD (variable speed drive) or VFD (variable frequency drive) compressors, operate by automatically adjusting the motor speed based on air demand.
First, it uses diodes to convert alternating current to direct current. The capacitor then cleans the alternating current and converts it to direct current using a transistor that acts as a switch. These switches control the frequency of power sent to the motor, which controls the motor’s speed.
Choosing the right air compressor for your business
As with any tool in construction, the efficacy of an air compressor depends on matching the right type of machine to the job at hand.
BISON has been engaged in the air compressor industry for many years. We are proud to manufacture a range of compressors that meet the expectations of our industrial customers.
Our experienced product experts can assist you in comparing several air compressors to choose the one that most closely matches your requirements for producing compressed air in an effective, dependable, and affordable manner. Contact us today to get started.
frequently asked questions about Air Compressor Types – Ultimate Guide
When should an oil-free compressor be used?
Some compressors are oil-free, which means the air they produce at the exit is clean. These compressors are more environmentally friendly. They are commonly used in the electronics industry, including semiconductor manufacturing, as well as in the chemical, pharmaceutical, medical, automotive assembly or food processing industries.
Make sure the compressor is ISO 8573-1 Class O if you require an oil-free one, as this is the only classification that guarantees complete oil-free. Higher ratings determine the maximum amount of oil in the compressed air, which usually requires an air dryer for them. These compressors, which do not provide very high pressures, are generally not designed for intensive use.
For piston compressors, lubrication can be replaced with a Teflon or silicone coating that protects moving parts. It can also be replaced with injected water or a closed loop water system. These compressors are usually louder but require less maintenance.
