1.设备转速：螺杆空压机的排气量与转速成正比，而转速往往会随电网的电压、频率而变化。当电压降低或频率降低时，转速将下降，使螺杆空压机排气量减少。
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.吸气状态：螺杆空压机是容积型压缩机，吸气体积不变。当吸气温度升高，或吸气管路阻力过大而使吸入压力降低时，气体的密度减小，相应地会减少螺杆空压机排气量；
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.气体泄漏：转子相互之间及转子与外壳之间在运转时没有接触，保持有一定的缝隙，所以会产生气体泄漏。压力升高后的气体通过缝隙向吸气管道及正在吸气的啮槽泄漏时，将使排气量减小。为了减少泄漏量，在从动转子的齿顶做有密封齿，主动转子的齿根开有密封槽，端面也加工有环状或条状的密封齿。如果这些密封线磨损，将使泄漏量增加，因此平时维护的时候应该考虑到这些因素；
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.冷却效果：气体在压缩过程中温度会升高，转子与机壳的温度也相应升高，所以在吸气过程中，气体会受到转子和机壳的加热而膨胀，因此相应地会减少吸气量。螺杆式空气压缩机的转子中有的采用了油冷却，机壳用水冷却，其目的之一就是为了降低其温度。当冷却效果不好时，温度则升高，螺杆空压机排气量便会减少。
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.