What is a 2-stage Air Compressor?

Compressors have sort of become a necessity in almost all industries. Air compressors help run pneumatic tools and inflate tires and pools using high-pressure air. There are two common types of air compressors, namely single-stage air compressors and 2-stage air compressors. In this article, we are going to focus on 2-stage air compressors and their work. Let’s go!

About 2-stage Air Compressors

2-stage air compressors are basically units that compress air in 2 stages. Fluid is compressed two times in these air compressors. This unit comes with two cylinders and each cylinder has a single piston. In total, the unit has two pistons.

One of these pistons is used for air compression while the job of the other piston is air transfer from one cylinder to the other. The major use of these air compressors is high-pressure applications. 2-stage air compressors differ from single-stage ones in the way that they compress air in two stages while single-stage units do it in one stage.

Working principle of 2-stage air compressors

In 2-stage air compressors, a connecting rod connects the crankshaft with the piston. The piston moves backward and forwards once the crankshaft begins rotating the piston. The crankshaft is connected to the crankcase. The cylindrical head has a valve cavity and is connected to the outlet valve as well as the inlet valve.

The following points describe the working of a 2-stage air compressor:

  • The crankshaft rotates when the prime mover that is coupled with it begins rotating. This leads to the reciprocating motion of the piston of the L.P cylinder.
  • Air is sucked through the filter and suction valve by the piston during this process. The low-pressure cylinder’s piston compresses air. This air is compressed to P2 pressure which is an intermediate pressure.
  • Once the air has been compressed to the required degree, it is sent to an intermediate pressure air cooler by the piston of the low-pressure cylinder. Here the air is cooled and then sent into the high-pressure cylinder. The required degree of cooling determines the ratio of the first stage compression.
  • In the high-pressure cylinder, the air is converted into high-pressure air using the up and down movement of the piston. This high-pressure air is then collected through the outlet valve.

2-stage air compressor components

Following are some of the major components of 2-stage air compressors:

1. Inlet valve

Also known as the suction valve, this valve is mainly used for sucking air into the cylinder from an external source.

2. Cylinder

This is a container that is used for air compression. 2-stage air compressors come with a high-pressure cylinder as well as a low-pressure cylinder.

3. Piston

This is used for compressing the air directly into the cylinder. It does this job by moving up and down inside the cylinder. The upwards movement leads to air being sucked in while the downwards movement compresses the air. Two pistons are used in a 2-stage air compressor, one with each cylinder.

4. Connecting Rod

A connecting rod forms a connection between the piston and the crankshaft. The movement of the connecting rod leads to the movement of the piston.

5. Intercooler

The intercooler helps cool down the air before it is forced into the high-pressure cylinder. This helps manage the temperature and stabilize the pressure.

6. Outlet valve

It helps discharge the compressed air and it is connected with the high-pressure cylinder.

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Uses of 2-stage Air Compressors

2-stage air compressors are quite useful in various industries. Following are some of the major uses of these units:

  • They have applications in bowling.
  • They can be used for running power tools.
  • They have major uses in the chemical and fertilizer industries.
  • They are also used in the plastic industry.
  • They also have some uses in petrol pumps.
  • These units are majorly used in the textile industry.

2-stage air compressors vs. single-stage air compressors Comparision

If you consider the cost, single-stage air compressors are much more affordable. However, when it comes to maintenance, two-stage air compressors are much easier to use as they have smaller parts so minimal maintenance is required.

The cost of operation for a 2-stage air compressor is also much less than that of a single-stage unit. This means that even though you are investing a slightly larger sum in the beginning, you will end up saving a lot of money in the long run.


2-stage air compressors have become very popular in the modern world. We hope our article helped you get an idea about these units and how they operate. We have tried to be as comprehensive as possible. Let us know if you have other questions.


How do I know if my air compressor is two-stage?

Answer: If your air compressor has 2 cylinders and 2 pistons then it is a 2-stage air compressor.

What type of air compressor do I need?

Answer: If you have frequent use for the unit and if you are working on heavy-duty projects then a 2-stage air compressor will work better for you. Otherwise, you can work well with a single-stage air compressor.