Different Types of Air Compressors – A Detailed Guide

Not only large and heavy industries but also home-based DIY enthusiasts rely highly on air compressors today. These machines are one of the go-to solutions to generate energy for powering up numerous tools and devices.

From immovable heavy-duty compressors to small and portable ones, a compressor is always essential for construction works. However, depending on the purpose and size of the project, the size of the compressor varies.

Today, we will be looking at different types of air compressors to get an in-depth idea of what these are and how exactly these machines work. So, let’s get started.

Compressor Parts

Although there are different air compressor types out there, here are some general parts of air compressors. You may not find all the parts in all air compressors. However, these are pretty much common in different machines.

  • Cylinder head
  • Suction valve
  • Piston
  • Crankcase
  • Crankshaft
  • Delivery valve
  • Compressor casing
  • Connecting rod
  • Cylinder liner
  • Bearings
  • Foundation
  • Bedplate
  • Inter-coolers
  • Suction filter
  • Oil strainer
  • Stage relief valve

Different Types of Air Compressors

Primarily there are two types of compressors, Positive Displacement and Dynamic. These two primary compressors are further divided into two different types each.

The Positive Displacement compressor has two variants - Rotary Screw and Reciprocating air compressor. Again, the Dynamic air compressor has two variants - Axial compressor and centrifugal compressor.

Below, we are trying to break down each type of compressor in detail. Let's get into it.

  • Positive Displacement Compressor 
  • Dynamic Air Compressors

Positive Displacement Compressor

Positive displacement compressors. There are different types of PD compressors that work in the same method. Although the mechanism of different PD compressors may vary, the basic principle for the compressors remains the same. Basically, the PD compressors have a cavity inside.

The machine draws air from outside and traps it inside the cavity. Then, the cavity slowly starts to minimize, putting pressure on the already-trapped air and thus to convert it into potential energy.

Rotary Screw Compressor

One of the most common Positive Displacement air compressor types is the Rotary Screw Compressor. This is probably the simplest type of PD air compressor that you can use. This one comes with a cooling system that works internally to cool it down for long-term running.

Plus, you don’t need to think much about the maintenance as it requires low care, too. These compressors are basically used in industries, so these are typically large in size.

Being industry-grade machines, you may need to lubricate the machine with oil. However, there are some versions that run without the oil, as well.

The Rotary Screw Compressor has two different internal rotors that are placed exactly on the opposite side of each. These rotors run to generate the energy from the machine. Outside air is easily trapped between the rotors.

After getting trapped, the pressure inside starts to increase. This allows it to provide power as needed. It can be used without a break for a long time, thanks to its cooling technique. These machines can generate up to 350 Horsepower.

  • Rotary Screw Compressor
  • Reciprocating Compressors

Reciprocating Compressors

The Reciprocating compressor is the second type of PD compressor. These are mainly used in small-scale industrial works, for example, house construction and garage work. The reciprocating compressor is not designed to be used for a long, restless time.

It comes with a few more internal moveable components than the Rotary Screw one. You need to lubricate all these organs for a smooth operation.

The mechanism of the compressor is performed with a piston. This piston is placed in a cylinder. The cylinder works to compress the air and also displaces the air for building the air pressure. A Reciprocating compressor can be found in two variants - single-stage or multi-stage compressors.

Single-stage compressors are for small-scale works, while multi-stage compressors are for larger jobs to be done. A multi-stage Reciprocating compressor can generate up to 30 Horsepower.

Dynamic Air Compressors

The second major type of air compressor is the Dynamic Air compressor. It produces high horsepower by rotating blades at a rapid speed and immediately trapping the air to build pressure.

The static energy that is found in the compressor is the stored kinetic energy produced in this manner. Dynamic Air Compressors are of two types - Axial air compressor and centrifugal air compressor.

  • Axial Air Compressor 
  • Centrifugal air compressors

Axial Air Compressor

The Axial air compressors are hard to find in usual construction projects. However, you can find these compressors in engines of airplanes and ships.

These machines are highly efficient, so the rate is also quite higher than any other compressor. You can expect the horsepower to rise up to thousands using this machine.

Centrifugal air compressors

The second type of Dynamic air compressor is the centrifugal air compressor. These work by slowing down the air that comes via a diffuser. It also cools the air down and thus generates energy.

As the compressor follows a multi-level compression procedure, these compressors can produce energy in higher quantities within a very small machine. 

The best part is, you don’t need to spend much time and money on maintaining these air compressors. Compared to reciprocating or rotary compressors, these machines need less care.

These machines are typically used in chemical plants or steel-making plants. On top of all, these compressors can generate up to 1000 horsepower.

How to Choose the Right Air Compressor?

Apart from the power output and energy-generation capacities that we have discussed till now, there are several factors that need to be considered to pick the right air compressor. Here’re the details.

Consider Oil-free Air Compressors

Most air compressors use oil as basic lubrication that can eventually cause fumes that can contaminate the air. It also means you need to run more cleaning work. It’s better to use an oil-free air compressor for a cleaner output.

Energy-Efficiency

Try to go for the air compressor that comes with a variable-speed option. This way, you can control the speed depending on your output needs, thus saving energy.

On the contrary, using a fixed-speed compressor will burn the same energy at a lower output level, as well, which will waste energy for sure.

Natural-Gas Operated

Many industries use natural-gas run air compressors for better output. Going for natural gas instead of electricity or diesel increases efficiency and output. You can check out the

Portability

Lastly, if you plan to keep the air compressor with you while you move from site to site, it’s better to look for portability in it. Go for compact and lightweight compressors for efficient mobility. You can check out the best 6 Gallon air compressor list here to pick one.

How to Determine Your Air Compressor Size?

Determining the air compressor size is quite crucial. Here’s a step-by-step guide to find out the air compressor size you need.

Find out your air requirements. Check with the manufacturer for your average CFM need.

Once done, you have to add the total CFM required. Say you need 80 CFM.

Now allow some leak

Determine the duty cycle of the compressor. Say you want it to be 70%. So you need to use 80 X 70% = 56 CFM to pick the proper compressor.

Find out the psig requirement. Typical air tools will need around 100 psig. Check the manufacturers’ guide to determine the right amount.

Check the phase and voltage of the space where you are going to put the compressor.

Finally, find out the tank size based on the CFM of the compressor you have calculated. Usually, the size varies from 80, 120, and 240 gallons.

Final Words

As you can see, different types and sizes of projects demand different types of air compressors. Consider your project before picking up one. If you are a home-based DIY guy, you may want to go for a smaller version with excellent portability.

Then again, if large projects are what you are dealing with, not to worry. You’ve always got the choice to get your hands on some of the giants in the market, too.

All the very best for your next project!

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