If you are looking into piston air compressors, then you will undoubtedly have come across the distinction between 1-stage and 2-stage piston compressors.
One of the most important things to remember (and we will cover this in more detail below) is that the number of stages has nothing to do with the number of cylinders. It’s a common misperception that makes the selection of the right compressor more confusing than it has to be.
If the difference between 1-stage and 2-stage piston compressors is unclear to you, or you want to know how a piston works in the first place, then this article will hopefully provide the information you are looking for.
Most people have probably seen a model of how an internal combustion engine works. A piston compressor functions in a similar way and also has the same components, namely a crankshaft, a connecting rod and piston, as well as a cylinder and a valve head.
The cylinder is filled with ambient air. When the motor starts to drive the crankshaft, it pushes the piston down into the cylinder and a vacuum is created above it. When it moves back up, that air is compressed and pushed into a tank. With each stroke, the pressure in that tank increases as more air enters with no place to go.
The difference between 1-stage and 2-stage piston compressors
The main difference between a 1-stage and a 2-stage piston compressor is how often the air is compressed between inlet valve and tool nozzle. As the name indicates, in a 1-stage (or single-stage) compressor, it is compressed once and in a two-stage compressor twice.
In the former, the air is routed to a storage tank after being compressed in a single stroke. In the latter, however, the air is moved to a smaller piston via a cooling tube that reduces the air temperature. There it is compressed for a second time, which results in an increase in pressure.
Uses for 1-stage and 2-stage piston compressors
Because the pressure of the compressed air generated by a 1-stage piston compressor is lower (a maximum of 10 bar), these less expensive models are usually the right choice for smaller jobs that do not require a continuous air supply. That not only includes compressors used at home but also those in many small businesses. Typical applications include nail guns, sanders and drills.
Conversely, 2-stage piston compressors are used for jobs requiring high-powered tools and a continuous supply of compressed air. They can generate an air pressure of up to 30 bar, which is sufficient to power lifts, paint sprayers, ratchets and other heavy-duty pneumatic tools typically found in production facilities.
An important note
As mentioned above, a common mistake people make is that they confuse the number of cylinders with the number of compressor stages. The designations of 1-stage and 2-stage piston compressors has nothing to do with the number of pistons. A single-stage compressor, for example, can have one, two or even three pistons. These terms merely describe which process is used to compress the air.
However, if you still have questions about this or any other issue related to 1-stage and 2-stage piston compressors, then an Atlas Copco specialist stands ready to support you.
Ask an air system professional about the best options for your needs.