What are air compressors? Technically, air compressors are machines that convert one form of energy into another form, which can then be stored and used at a later point in time. But neither that brief explanation, nor the more detailed description below do this invention and its profound impact on our lives.
That is why it is "The machines that have changed our world more than almost any other invention.”
What may sound like hyperbole is actually a very accurate description of the impact air compressors have had on our society – and especially the industrial sector. In less than 150 years since Austrian engineer Viktor Popp built the first compressor plant, compressed air has become so indispensable that it is now referred to as the “fourth utility” along with electricity, water and gas.The numbers back up this bold statement. It is estimated that 10% of all electricity consumed by the manufacturing industry is used for compressed air.
To understand the importance of compressed air and the compressors that generate it, let's first take a closer look at the physics of it. Compressed air is simply regular air that is forced into a much smaller space. When this happens, its molecules speed up and so-called "kinetic energy" is created. That kinetic energy can either be used right away or it can be stored and released later.
One of the reasons compressed air has become so indispensable is its versatility. Just about every industry relies on compressed air in some form – from manufacturing plants to cars, ships and trains, construction sites to hospitals, compressed air is used all around it.
However, the many options also make it difficult for laypersons to find the compressor that is right for them. To make things easier, here is an overview of different compressor types and technologies.
First, let’s take a look at how compressors work. There are two main compression technologies. Positive displacement compressors have a cavity that is filled with regular air (or another gas at atmospheric pressure). That cavity then becomes smaller, which means the same amount of air has to fit into a smaller space and its pressure and kinetic energy increases. Dynamic compressors achieve the required rise in pressure by accelerating the air (or gas) with an impeller and then slowing it down in a diffuser.
Positive displacement compressors are much more frequently-used and they feature different technologies to displace the air. Piston compressors use a reciprocating motion, rotary screw compressors a single rotor and the more seldomly utilized scroll compressors feature a double rotor.
Each of them has their different benefits and uses. Piston compressors, for example, are fairly simple machines that are inexpensive to buy. They are often the right solution for operations with a low compressed air demand. Rotary screw compressors are more advanced and offer a low total cost of ownership. They are more energy efficient and can produce a lot more compressed air. Dynamic compressors, on the other hand, are primarily used for operations and applications that require very high volumes of air.
