Modern compressors are small, powerful technical marvels that are easily accessible to homeowners. This was not always the case. In the past, reaching 8 bar capacity require much larger equipment, which usually ran on heat or require large amounts of electricity, which only professionals could do.
How does a compressor work and what are its tasks?
How a compressor piston works
An air compressor works on a very simple principle: when air is compress, its volume decreases as the pressure increases, so that the compress air is store in the compressor.
This is most often done with a piston compressor, the most common type of compressor in the world. If you are familiar with the workings of an internal combustion engine, you will easily understand how a very similar piston compressor works.
How a piston compressor works
Each piston compressor has a crankshaft, connecting rod, piston, cylinder, and valve head. Energy is require for the entire operating mechanism.
Industrial Air compressors are usually power by electricity or natural gas, depending on the model. Most compressors are also equip with an air accumulator to maintain stable air pressure and extend their life.
But back to the mechanics: here’s a diagram that explains how the pistons in the cylinders work.
At the top of each compression cylinder is a valve head that contains an intake valve (inlet valve) and an exhaust valve (outlet valve). They open and close at regular intervals and are locate at the top of the valve head. As the piston moves downward in the cylinder, a vacuum is create in the space above the piston in the same way that the plunger of a syringe is pull.
The pressure difference in the cylinder creates a vacuum that draws in outside air after the intake valve opens. The air entering the cylinder is then compress by the rising piston, the intake valve closes and the exhaust valve opens. The compress air accumulates in the tank, increasing the pressure.
Double Piston
Dual piston compressors are also very common. They operate in the same manner as their single-piston counterparts. The only real difference is that there are two strokes per revolution instead of one. The most common variation of a dual piston compressor is a two-stage system, where one piston pumps air into the second cylinder to create more pressure.
To keep the pressure within the require limits and prevent the tank from exploding, each air compressor is equip with a switch that cuts off power to the motor when the pressure in the tank reaches the limit (usually around 8.6 bar). To calibrate the pressure to the power tool connect to the compressor, the compressor is equip with a regulator and pressure gauges on the front and back.
There is a safety valve as well as a bypass valve to reduce the pressure in the tank when the compressor is not in use.
Lubrication
Another important thing to know about air compressors is how they are lubricate. Oil-lubricate pumps have an oil reservoir in the cylinder to lubricate the bearings and cylinder walls. The air and oil are separate by piston rings, but they are not reliable. As a result, air and oil sometimes mix when you use a compressor to apply paint, which can be troublesome.
There are different forms of grease, the most common being aerosol grease, . But there are also special greases for oil pumps, hermetic compressors, or screw compressors.
