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Which Air Compressor Is Right for Your Job?

By In Information On July 15, 2016


Air compressors are among the most useful pieces of equipment in any industry. They meet diverse needs in chemical manufacturing, aerospace engineering, and mining jobs, as well as in the medical and food and beverage industries.

Because air compressors serve such varied clients, they come in many shapes, sizes, and types. If you want your air compressor to help you succeed in your industry, you need to choose the right one for the job.

Below, we’ll discuss the most common types of air compressors. Once you finish our blog, you should have a much better idea of how to choose the perfect air compressor for your commercial or industrial job.

Rotary Screw Compressors

Rotary screw air compressors have two rotors that spin in opposing directions. The rotors turn closely to each other, and as they turn, they pull in air from the air end of the rotors. Then, air travels through the rotors to the pressure side of the rotors.

When the air first enters through the air end of the machine, a filter removes dirt and dust to ensure that clean air enters and cycles through the compressor.

If you have an oil-injected rotary screw compressor, oil gets released into the machine while it operates. As the machine compresses the air, the air heats up and the oil cools the air down to a safe temperature. Oil also ensures that all of your compressor’s moving elements work together smoothly.

Once the oil cools the air, separator elements inside the compressor filter oil out from the air. The filter removes any dirt that the oil could have picked up inside the compressor. After a cooling element cools the oil down, the oil cycles back into the compressor. Once the cooling element cools the air even further, the air leaves the compressor, ready for use.

Oil-injected rotary screw compressors work perfectly for most industrial applications. However, some applications require entirely oil-free air-although most oil is filtered out of the air in an oil-injected machine, a tiny percentage escapes with the air.

Oil-free rotary screw compressors have to use a different method to cool the air. It cycles through the unit in two stages instead of just one, so the machine is more difficult to repair, and more expensive than oil-injected compressors.

No matter which type of rotary screw compressor you choose, you can expect a relatively quiet machine that provides you with the required amount of compressed air. These machines are more energy efficient than other types of air compressors, so you can save more money over time by investing in one.

However, in the smaller horsepower range, 5-25 hp, rotary screw compressors are more expensive piston compressors.  Servicing them as needed is crucial and maintenance is more complex (and therefore more costly), but you need to fix any problems early on before they turn into more expensive repairs.

Finally, you need to run your rotary screw compressor for a certain amount of time each day or week. Otherwise, the condensation that forms in the unit could cause oil contamination, which could lead to premature compressor failure.

Reciprocating Piston Compressors

Unlike rotary screw compressors, these compressors use pistons to pressurize the air.  Generally these compressors are used in the lower, 5 – 25 hp, applications or where higher than 150 psig is required.  The piston simply moves back and forth quickly to compress the air. Piston compressors generally have more moving parts than rotary screw compressors, and you can find oil-free varieties as needed (though they’re more expensive than systems that use oil).

Reciprocating piston principles are similar to an automobile engine.  The air enters through one valve and exits through the other. Electricity or gas powers the compressor and turns a crankshaft that enables the piston to work.

This type of air compressor is less expensive and easier to maintain than a rotary screw compressor. However, it’s also much louder-if you’re in the same room as the machine, you won’t be able to operate it without wearing some sort of ear protection.

Scroll Compressors

These types of compressors are generally used in medical and in industrial applications where oil free air is required. They produce a lower air flow than the two other types we’ve mentioned here, and they’re generally small in size.

Scroll compressors use spirals to rotate the air. One spiral-shaped component stays still while the other spiral-shaped component spins. The spinning motion traps the air, which is pressurized in the middle of the unit.

Scroll compressors are small and simple, which makes them easy to maintain. They’re quiet and usually oil free. However, they’re expensive and get much hotter than most reciprocating piston or rotary screw air compressors. If a part of your scroll compressor breaks, you’ll likely have to replace the whole unit instead of just one component.

Which Air Compressor Should You Choose?

The type of air compressor you need depends on your budget and air flow requirements.

If you work in a lab and only need a small amount of clean air every once in a while, a scroll compressor might be your best bet. If you need quite a lot of air that doesn’t need to be 100% oil-free, choose a rotary screw compressor. If you need a less expensive, lower horsepower unit that requires less technical maintenance, choose a reciprocating piston compressor.

Now that you’ve read through our general information, you have a better understanding of which air compressor will best suit your needs. To get a more in-depth analysis, get in touch with the professionals at Compressor-Pump & Service, Inc. We’re happy to evaluate your requirements and pair you with the perfect air compressor at the right price.


About the Author

enelson@compressor-pump.com

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