How Does An
       Air Compressor Work

How does an air compressor work?

This question was posed recently on the ASK page on this site by a student.

I suspect that this question crosses folks minds from time to time, so I am glad to share my answer with you.

The Question

I am in school and am doing a science project.

We need a pneumatic system and I chose the air compressor and I need to have a good explanation of how it works. I don't really need to know all the little things, just basically what happens.

I couldn't find the answer anywhere and we are supposed to look it up on a site. Thanks.

My Response

Hi Emily, and thanks for sending in your question.

Did you know that the air you walk around in, and breathe, is already compressed? The pressure generated at sea level by the weight of the air above itself generates 14.7 PSI of pressure.

PSI stands for pounds per square inch, and is a measure of force.

An air compressor takes free air (air at 14.7 PSI actual) into an intake port on the compressor pump, and using mechanical means (pistons, screws, rotary sliding vanes ) pushes that air into a smaller area. As more and more air is pushed into the smaller area (the receiver or the air tank on a compressor) the pressure continues to increase inside that tank.

There is a pressure switch which monitors the air pressure inside the tank. When the air pressure reaches the high pressure level setting on the switch it shuts the compressor off.

When someone uses compressed air from the tank, the air pressure inside the tank will start to fall. When it reaches the pressure switch low pressure setting, the switch turns the compressor back on allowing it to compressor air into the tank again.

This cycle continues as compressed air is being drawn from the compressor tank, until the pressure inside the tank again reaches the high set point, and the pressure switch shuts the compressor off again.

There is lots of information on this site about the different types of compressors, and the problems compressed air generates. Please help yourself to any of that information if it will help.

Cheers,

Bill