Calculations and Formulas

CFM Calculator

Pipe Velocity Calculator

Receiver Selection & Sizing Analysis 

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  1. CFM of compressed air required to raise a known system pressure
    to a desired system pressure:C2 = Required CFM total
    C1 = Existing or known CFM
    P2 = Desired pressure
    P1 = Known PressureformulasEXAMPLE: A 75 HP Compressor rated at 320 CFM t 125 PSIG will hold only 85 PSI and we desire 125 PSI.

    C1 = 320 CFM
    P2 = 125 + 14.7 (139.7)
    P1 = 85 + 14.7 (99.7)
    C2 = 448.39 Total CFM required

    We need an additional 128.39 CFM to raise system pressure to the desired level.

  2. Simple Energy Formula:Motor Efficiency = Cost per KW X .746 (Power Factor) X Hours of operation X Brake horse power*Note: No electric motor is 100% efficient, most will average 92-95% efficient.
  3. PSI VS. BHP (Rule of thumb):For every 1 PSIG pressure drop, BHP (Brake horsepower) goes down ½ %.