By . Air Compressor. At Sunday, September 16th 2018, 04:24:15 AM.
A rotary vane air compressor uses a rotor and a number of blades in radial slots in the rotor. I do not fully understand how this works, but it has something to do with the rotor turning and the blades sliding in and out of their slots as they keep contact with the housing wall. This somehow creates decreasing volume.
Years later, I built a smaller woodworking shop in my home which only required one air sander running at a time. For that shop, I purchased an air compressor half the size and isolated it in a soundproof room in one section of the shop. I ran galvanized pipe under the shop floor to three regulators at three different connection locations. The machine I purchased for that shop as a 5 HP Ingersoll Rand model with an 80 gallon tank. At the 80 PSI required by my Dynabrade sander, the compressor would produce enough air from morning to night. I must say that that compressor was very well built. All I had to do was keep an eye on the oil level in the sight glass. At night, I would turn off the master air valve on the side of the air compressor, leaving the electricity on, to silence the compressor until the next work day.
Air output of a compressor is expressed in standard cubic feet per minute (SCFM) or just cubic feet per minute (CFM). Not all 5 HP compressors put out the same volume of air per minute. This is a function not only of motor horsepower but also the efficiency of the air compressor pump the motor is powering. The higher the CFM, the less your air compressor will have to cycle on and off to keep up with the demands you are putting on it. A small compressor pump on a huge tank will produce no more air than on a small tank. The only difference will be in the number of times the compressor cycles on an off each hour and the time it takes to recompress the tank on each cycle. In the final analysis, you need to pay attention to SCFM (or CFM) more than you do motor horsepower or tank size. Air flow is the end product of any compressor and the CFM must be sufficient to the job at hand.