Cement Manufacturers Association (CMA)

21 Annual (p.a.) fixed costs include Depreciation of the investment made • Interest rate • Space utilization costs Variable costs are made up of • Energy costs over the full-load periods and no-load times of the compressors • Costs of consumables such as oil, coolant etc. p.a. • Maintenance and costs The largest part of the costs, at approx. 75%, is taken up by the energy costs. In order to generate 1 Nm³ of compressed air, modern compressor stations require between 100 and 120 Wh/Nm³ (compressed air index [kWh/Nm³]) Howmuch do leakages cost? Even small leakage offers the potential for significant savings. The table below shows how much air is lost as a result of leakages with a specific hole diameter and what additional costs are incurred: a For well-rounded orifices, values should be multiplied by 0.97 and by 0.61 for sharp ones. b Used with permission from Fundamentals of Compressed Air Systems Training offered by the Compressed Air Challenge®. Leakage rates a (cfm) for different supply pressures and approximately equivalent orifice sizes b S.No Orifice Diameter (inches) 1/64 1/32 1/16 1/8 1/4 3/8 70 0.29 1.16 4.66 18.62 74.4 167.8 80 0.32 1.26 5.24 20.76 83.1 187.2 90 0.36 1.46 5.72 23.1 92 206.6 100 0.40 1.55 6.31 25.22 100.9 227 125 0.48 1.94 7.66 30.65 122.2 275.5