There are many factors affecting the displacement of piston compressor, which can be summarized as follows:
1) the reduction of the rotation speed of the prime mover (usually Motor) driving the compressor (due to the low voltage or the reduction of the grid frequency) or the loose belt will cause the reduction of the rotation speed of the compressor, which will reduce the exhaust volume;
2) if the volume of surplus space exceeds the designed value, the displacement will decrease significantly;
3) the increase of suction resistance (including the resistance of air filter, suction pipe and air valve) will reduce the gas pressure in the suction cylinder, reduce the suction volume, and accordingly reduce the exhaust volume;
4) the cylinder cooling is not sufficient, and the temperature of the cylinder wall rises, which makes the inhaled gas be heated, and the volume expands, resulting in the reduction of the suction volume, and finally naturally affects the reduction of the exhaust volume;
5) the increase of external leakage of the compressor will directly reduce the displacement. External leakage can be divided into two types: one is that gas directly leaks into the atmosphere or the first-stage air inlet pipe, and this part of leakage directly leaks out of the compressor, which obviously belongs to external leakage; secondly, in the process of expansion or suction of the first level cylinder, the gas that the high pressure level leaks to the first level cylinder through the first level exhaust valve due to the untight closing of the exhaust valve also belongs to external leakage. External leakage often occurs in the position of the stuffing, piston ring, suction and exhaust valve, etc. Therefore, these parts are not tightly sealed, which will cause external leakage of compressed gas and affect the air discharge of the compressor.
