Harry caught our cameras in a renovation centre and asked the simple question: "How many pneumatic tools can I run off of a single compressor at the same time?"
Technically the answer is simple, in reality much more complex.
Every compressor has a rating on it stating that it can give a constant maximum supply of "X" SCFM at a given pressure, usually 90 psi.
An SCFM, Standard Cubic Feet per Minute, is a standardised way of measuring air flow. In principle, every pneumatic tool has a SCFM rating. So in principle, you simply add up all the tools you want to use at the same time, add together the SCFM ratings and get a compressor that is as big or bigger than the sum.
The first catch is that none of our tools had a SCFM rating anywhere we could find. This may be because sizing a compressor is not really that simple.
Impact tools like nailers use a certain quantity of air with each nail, but it's overall air requirement is highly dependent on how fast you are driving how many nails.
Rotary tools and sprayers use much more air because the air continues to flow as long as they are operating.
So the demand on the compressor varies a great deal with real usage. You can hook up a lot of tools on a small compressor if they are not all consuming air at the same time or not working flat out.
Secondly, the size of the compressor can be confusing since more and more compressors are holding air at higher and higher pressures. Rather than 125 psi, our compressor holds air at 175psi. That simply means that you have more air in a smaller tank.
In reality the best measure of the size of the tank against the tool usage is the actual in the field cycling time. If the compressor is running more than 50% of the time, you will shorten the life of the compressor. It is working too hard and will burn out. Occasional short stints of short cycling is not so bad, but if it is always short cycling, you need another tank, or a larger capacity tank.
If it can't even keep the pressure up at the tool that means that it is running 100% of the time and it will die shortly.
Unless of course low pressure might be caused by long 1/4 inch hoses and standard couplings. Full flow couplings, and larger hoses, at least up to the last length, allows all the air of the tank to get to the tool.
The compressors in the photos are made by Porter Cable.