Here are the TOP TEN Compressed Air "Rules of Thumb" – designed to respond to the questions that industrial air compressor users ask about most.
1. CFM delivery per Horse Power at 100 PSIG:
• For "home owner" type of air compressors---2 to 2.5 CFM per HP
• For Industrial Air-cooled 2-stage air compressors----3.5 CFM per HP
• For Small Vane & Screw air compressors (25 HP or less) 4 CFM per HP
• For large Piston, Screw & Centrifugal air compressors--4.5 to 5 CFM per HP
NOTE: THE MORE CFM PER HP - THE LESS ENERGY USED.
2. Air Receiver Size needed for these types of inlet control:
• Modulating Control---------------0 to 1 gallon per CFM
• On-Line/Off-Line-----------------3 to 4 gallons per CFM
• Stop-Start/ Variable Speed-------4 to 6 gallons per CFM
NOTE: THE MORE AIR STORAGE - THE LESS ENERGY USED
3. Amperage per Horse Power:
115 Volts------- 1 phase-------- 10 amps per horse power
230 Volts------- 1 phase-------- 5 amps per horse power
208 Volts------- 3 phase-------- 3 amps per horse power
230 Volts------- 3 phase-------- 2.5 amps per horse power
460 Volts------- 3 phase-------- 1.25 amps per horse power
574 Volts------- 3 phase-------- 1 amp per horse power
NOTE: THE MORE ENERGY EFFICIENT THE MOTOR - THE LESS ENERGY IS USED.
4. Air Piping Size by CFM and Pressure Drop:
• Compressor Room Header---0.25 PSIG pressure drop per 100 feet of piping
• Main Line-----------------0.5 PSIG pressure drop per 100 feet of piping
• Loop Line-----------------1 PSIG pressure drop per 100 feet of piping
• Branch Line---------------2 PSIG pressure drop per 100 feet of piping
NOTE: THE LESS AIR PRESSURE DROP - THE LESS ENERGY USED
5. Size Compressed Air Line Filters to be twice (2x) your compressor CFM flow rate.
• This will lower your pressure drop 2-3 PSIG and save an additional 1% on electrical energy costs.
• Elements will last twice (2x) as long and this can save on your maintenance costs.
6. Lowering Compressor Pressure settings 2 PSIG will result in a 1% energy savings.
7. Lowering Compressor Inlet Air Temperature 10° F will result in a 2% energy savings.
8. The average energy cost to operate an air compressor is approximately $0.10 per horse power per hour.
9. Compressed Air system leaks totaling the size of a 1/4" orifice, at 100 PSIG, running 24 hours a day will waste approximately $15,000 worth of electrical energy a year.
10. Using Synthetic Compressor Lubricants can save you up to 9% of the energy cost of operating your compressor as compared to using a non-synthetic lubricant.
COMPRESSED AIR DEFINITIONS:
- CFM= Cubic Feet per Minute - Volumetric air flow rate.
- Inlet Pressure = The actual pressure at the inlet flange of the compressor.
- PSIG= Pounds Per Square Inch Gauge
- AMPS=Abbreviation of the plural for Ampere, a unit of electrical current
- Pressure = Force per unit area, measured in pounds per square inch (psi).
- Pressure Dew Point = For a given pressure, the temperature at which water will begin to condense out of air.
- Inlet Temperature = The total temperature at the inlet connection of the compressor.
