1. Equipment speed: the displacement of screw air compressor is directly proportional to the speed, and the speed often changes with the voltage and frequency of the grid. When the voltage or frequency is reduced, the rotating speed will decrease, which will reduce the air displacement of screw air compressor.
2. Suction state: screw air compressor is a volumetric compressor, and the suction volume remains unchanged. When the suction temperature increases or the suction pressure decreases due to the excessive resistance of the suction pipe, the density of the gas decreases, which correspondingly reduces the exhaust volume of the screw air compressor;
3. Gas leakage: there is no contact between the rotors or between the rotors and the shell during operation, and there is a certain gap, so gas leakage will occur. When the pressure increases, the gas will leak to the suction pipe and the meshing groove, which will reduce the exhaust volume. In order to reduce the leakage, a sealing tooth is made on the tooth top of the driven rotor, a sealing groove is opened on the tooth root of the driving rotor, and the ring or strip-shaped sealing teeth are also processed on the end face. If these sealing lines are worn, the leakage will increase, so these factors should be taken into account during maintenance;
4. Cooling effect: the temperature of the gas will rise during the compression process, and the temperature of the rotor and the casing will also rise accordingly. Therefore, during the suction process, the gas will be expanded by the heating of the rotor and the casing, so the suction capacity will be reduced accordingly. Some rotors of screw air compressor are cooled by oil, and the casing is cooled by water. One of the purposes is to reduce the temperature. When the cooling effect is not good, the temperature will rise, screw air compressor exhaust will be reduced.