What must I watch when comparing power consumption of such compressors quoted by different manufacturers?
Power consumption of an air compressor is the sum of: • The aerodynamic power required to compress a given amount of air including power needed to overcome inter-stage pressure losses; and • Mechanical losses. Aerodynamic power is influenced by several parameters. It is proportional to weight flow, inlet-air pressure, inlet-air density, cooling-water temperature, humidity, and discharge-air pressure. It is also inversely proportional to inlet-air temperature and cooling-water temperature. When trying to compare power consumption of different compressors, we must make sure we compare “apples with apples.” We must state power consumption under the same conditions for ambient air and cooling water. Weight flow must also be at the same conditions for all compressors being considered, and must take into account the effect of humidity. Because different manufacturers of compressors may give slightly different flows with different powers, it would be well to compare specific power consumption
