Calculating Costs
This graph provides a method for determining the cost of the total pressure drop in your entire system – from the compressor to the point of use . Locate your Electric Utility Rate on the horizontal axis; read upward to intersect the line that corresponds to your compressor horsepower; read left to the vertical axis to determine the cost of each psi drop in pressure for a compressor operating three shifts at 8760 hours per year. Multiply the annual cost per psi ($/psi) by the total pressure loss.
If your compressor operates less than 24 hours a day, multiply the cost determined from the graph by actual hours of operation per year dived by 8760. Example: pressure loss during single shift operation at five days a week or 2080 hours per year would cost 2080 divided by 8720 or about 24% of the cost determined from the graph. This is the ongoing annual cost necessary merely to compensate for pressure loss in your system.
EXAMPLE: Pressure at air compressor (100 hp) is 120 psig, pressure at point of use is 100 psig = 20 psi drop. If operation is 24/7, kWh is 8 cents your pressure drop cost is $10,000 per year. (8 x 500 x 20). Single shift operation = $2,400 per year.
