Compressor Formulas : A Free Cheat Sheet

Compressors are an essential part of many industrial processes, and understanding the formulas related to them is crucial for achieving optimal performance. Below are some important industrial compressor formulas that can help you improve the efficiency and effectiveness of your compressor systems.

Compressor Formulas

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1.Compression Ratio Formula: Compression ratio is the ratio of the inlet pressure to the outlet pressure of a compressor. Compression Ratio = P1/P2.  Where P1 is the inlet pressure and P2 is the outlet pressure.

2.Volume Flow Rate Formula: Volume flow rate is the amount of air (or gas) that flows through the compressor in a given amount of time. The formula for volume flow rate is: Volume Flow Rate = (Q x 60) / (T x 14.7). Where Q is the compressor flow rate (CFM), T is the time (minutes) and 14.7 is the standard atmospheric pressure.

3.Power Formula: Power is the rate at which work is done by a compressor. The formula for power is: Power = (Pressure x Volume) / Time. Where Pressure is the compressor pressure (psi), Volume is the compressor volume flow rate (CFM) and Time is the compressor time (minutes).

4.Efficiency Formula: Efficiency is a measure of how effectively a compressor converts energy into work. The formula for efficiency is: Efficiency = (Output Power / Input Power) x 100%

5.Compressor Specific Power: Specific power is the power consumed by the compressor per unit of mass flow rate. The formula for specific power is: Specific Power = Power / Mass Flow Rate

6. Compressor Adiabatic Efficiency: Adiabatic efficiency is a measure of how effectively a compressor converts energy into work without any heat loss. The formula for adiabatic efficiency is: Adiabatic Efficiency = (1 – (T2/T1)^((k-1)/k)) x 100% where T1 is the inlet temperature, T2 is the outlet temperature, and k is the specific heat ratio of the gas.

Additional Useful Formulas

1. Converting Kilowatts to Horsepower: There are .746 watts per horsepower. Multiply compressor horsepower by this number to get KW. For this example lets say we have a 25 hp compressor.

25 x .746 = 18.65

Therefore, a 25HP compressor is 18KW

2. Gallons (volume) = cubic feet/ 0.134

3. Cubic Feet = gallons/7.48

4. Tank Pump Uptime (in minutes) = volume (gal) X (final pressure – initial pressure/ (7.48 X atmospheric pressure X pump capacity (CFM))

By understanding and applying these formulas, you can optimize the performance of your compressor systems, improve efficiency, and reduce energy costs.

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