Compressed air is widely known as the 3rd utility, the first two are electricity and water supply, respectively. Wherever you are, you will "see" their presence, in a car workshop the mechanic changing tires with an impact wrench by removing the nuts. When you see a fire extinguisher, what filled inside is compressed gas(carbon dioxide to be exact) served as propellant. Why the term 3rd utility? plainly because roughly all manufactures be it at a automobile, semiconductor, pharmaceutical or even dentists to run the drill, they need compressed air. Without compressed air, manufacturers or your mechanic will be changing tires with brute force and cannot work efficiently.
Most manufacturing machinery requires at least some sort of energy to power them. For normal application and non heavy duty jobs, compressed air is the best option due to cleanliness if compared to a hydraulic system.
Compressed air are generated by air compressors, many types of compressors are available in the shop these days such as piston type, screw element type, scroll type, vane type, and high volume centrifugal/turbo type just to name a few. However, we will clarify on the compressors type in the time to come topic.
Basically an air compressor gets its "source" from ambient, air traveling through inlet air duct and into a compression chamber. Inside the compression chamber, overpressure will be created by reducing the air volume rapidly.
For example, we refer atmospheric pressure as 1 atm or 14.7 Psi (pound per quadrate inch) which means there are 14.7 pound of force being exerted on our body and any objects per quadrate inch at sea level.
Formula:
Absolute Pressure(abs) = Atmospheric pressure(atm) + Gauge pressure(g)
For example, a normal mechanic air tool operates at about 100 Psig, which means 14.7 Psi(atm) + 100 Psig = 114.7 Psi(abs). Do note the variation and not to be confused by it.
Compressed air can range from as little as 30 Psi(abs) for artist air brush up to 20,000 Psi(abs) at some petrochemical, oil and gas, and mining application. For the advantage of our readers, compressed air are not to be taken lightly as they pack a lot of energy. A Bb gun with 150 Psi(abs) gas cartridge, firing pellets at this force can cause serious injuries if gamers do not have proper protection.
Therefore we utilize its compel to carry out inescapable jobs which are too dangerous for a person. With its safety asset like non electrical conductor and do not create sparks. This is why compressed air operated instruments are preferred in explosion prone area. For example, a compressed air controlled water valves in a natural gas plant, steam plant or even a nuclear reactor plant where it is best control remotely via a control system. With just a flick of a switch, compressed air can shut or open the valves with ease.
The Basic of Compressed Air