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Performance Verification:

The members of the Compressed Air & Gas Institute (CAGI) have long been involved in standards for the compressed air systems industry. CAGI has worked closely with the European Committee of Compressors, Vacuum Pumps, and Pneumatic Tools (PNEUROP), the International Organization for Standardization (ISO), and other standards development bodies to develop appropriate standards for compressed air and gas systems equipment.

For displacement type compressors, including rotary screw compressors, ASME Power Test Code 9 was for many years the recognized performance standard in the United States. ISO 1217 has replaced PTC 9. PTC 9 and ISO 1217 are too complex for performance testing in volume production. CAGI and PNEUROP developed Simplified Test Codes which have been incorporated as appendices to ISO 1217. CAGI members agreed that published performance of their products would be based upon the ISO 1217 annexes and data sheets were developed to provide a standardized method of presenting the performance data. The compressor data sheets allow a common basis for comparison of some relevant items.

For compressors, a useful tool to calculate energy consumption is the power cost formula. Power cost equals the brake horsepower that the compressor is using, times the conversion factor of point-seven-four-six, times the hours of operation, times the local cost of electricity per kilowatt hour. The result is all divided by the motor efficiency rating. Here's an example:

The yearly electrical cost of operating a 100 hp compressor that uses 109 brake horsepower consistently over 8000 hours, with a local electrical cost of 6 cents per kilowatt hour and a 93% efficient motor is $41,968.

The information necessary to plug into the power cost formula can be found on the data sheets, which are sources of basic information about compressor performance. This information will help you make comparisons and select the compressor that best meets your needs.

CAGI has also developed a data sheet and performance verification program for refrigerant compressed air dryers to allow a common basis for comparison of some relevant items to aid in selection of compressed air dryers.

Additional information about compressed air systems, compressors, and dryers can be found in the CAGI Compressed Air and Gas Handbook.

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