Multiple stages are used for improved efficiency and higher pressures. These factors have an effect on rotor and housing expansion and deflections, housing strength, and bearing loads. Limiting factors in rotary screw air compressors are the discharge temperature and pressure, and temperature and pressure differentials across the machine. Water could still be injected into the compression chamber for cooling and sealing for higher pressures. In oil-free designs, timing gears are attached to the rotor shafts to prevent rotor-to-rotor contact. In oil or water injected designs, fluid is introduced in step B to remove the heat of compression, seal internal clearances, and prevent rotor-to-rotor contact. Figure 2 (below) is inverted to show both ports.
The discharge port is near the bottom at the opposite end of the housing. The air inlet port is located on top of the housing near the drive shaft end. The main rotor has helical lobes and the secondary rotor has helical grooves (Fig. Compression is accomplished by the main and secondary rotors synchronously meshing in a one-piece, dual-bore housing. Because size is a leakage factor, efficiency is greater in smaller compressors.Ī rotary screw uses two rotors to push air through the compressor, which creates pressure. 1), which has improved efficiency due to lower leakage or bypass in the discharge area. It has evolved from a simple circular profile to an asymmetric profile (Fig. Times have changed and the most popular air compressor design today that meets the industrial plant’s demands is the rotary screw. We want it dry and clean, and the efficient compressor should come in a box that is quiet. Today we know compressed air is an expensive fourth utility not to be wasted.
It came out of a hose along with some water and oil spray, and the compressor in the back room went chugga-chugga. Variable speed drives match the performance of the compressor to demand and reduce power consumption.Īt one time, compressed air was considered free. There is no metal-to-metal contact, which minimizes wear.