Compressed Air Piping Systems

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Flow Rate Calculator

Values for this calculator are based on:

  • smooth wall inside the pipe
  • pressure drop across the length of the pipe as 5 psi

Loop system: the entire length of the loop divided by 2
Straight line system: distance from the compressor to last outlet


THEORETICAL CFM

Take the calculated CFM and compare to the compressor output.
Adjust pipe size accordingly.
Typical compressor output is 3.8 cfm per horsepower.
Example:
(7.5 hp x 3.8 cfm= 28.5 cfm)

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Air consumption of common air tools in CFM at 90 psi
Tool
Brad Nailer 1
Blow Gun 5
Body Polisher 5
Cut Off Tool 12
Air Drill 10
Spray Gun 10
Impact ½" 15
DA Sander 15
Air Ratchet 5
Product Inside Diameter
Inches
RapidAir 1/2 .375
Maxline 1/2 .50
Maxline 3/4 .80
Maxline 1 1.03
Maxline 2 2.00
FastPipe 3/4 .690
FastPipe 1 .870
FastPipe 1-1/2 1.430
FastPipe 2 1.810
Fastpipe 3 2.990
FastPipe 4 3.67
FastPipe 6 5.57

When choosing the correct diameter for your piping system, remember that a larger size does increase air flow. However, a larger diameter will drive the cost of the system up. Size your air system for the tools you will use, the compressor horsepower and the size of your building layout.

The thread size of the port on your air compressor tank does not determine the pipe size for your piping system. It is calculated with the length of your piping (building size) and air compressor cfm output. Even though the port on your tank may be small, the air is only traveling through a short distance, so the restriction is minimal. Air is only restricted over a long distance with small piping.

For recommendations on system choices and building sizes, please see our CHOOSE A SYSTEM page.

To maximize the flow rate for any of our piping systems, it is best to install your system as a loop. Starting at the air compressor and looping around your shop back to the compressor. This will increase flow rate, decrease pressure drop, and allow smaller line size to be used.

Compressed Air Calculations