Portable air compressors were invented for the convenience of contractors who need to move their compressor from one place to another. Traditional industrial types of this machine were very large and very heavy, which makes transporting them a very tiring task. That is why when smaller and lighter versions of compressors became available; many contractors had a very positive reception on them.
There are many models of easily transportable machines available today, with different horsepower, pounds per square inch (PSI), tank size and cubic feet per minute (CFM). All these factors determine the functionality and the power output capabilities of the machine.
When we speak of horsepower in a portable air compressor, we mean its raw power. It can range from 0.3 in a small machine to a maximum of 5.5 in a bigger one. PSI readings usually range from 135 to 150, while CFMs range from 100 PSI to a low point of 0.75 to 8.9. There are also different sizes of tanks. DeWalt D55140 has 1 gallon capacity while Alton 25 has 25 gallons in capacity.
The sources of power may come from an electrical source or a gas-fed machine. In general, bigger machines are gas-powered since it can produce more power compares to electrical sources.