1, the opening pressure of the minimum pressure valve is about 4bar, to ensure that the pressure inside the cylinder is not lower than this minimum pressure when the air is output, so as not to reduce the separation effect of the oil-air separator caused by the air flow too fast. 

2、The oil cylinder should have a certain pressure when the machine starts to guarantee the lubricant circulation and provide the initial control pressure to the control circuit. 

3, with a one-way valve to prevent the pipe network compressed air back into the machine. 

Common corresponding faults:

1、 The cylinder safety valve sprays air during operation. This fault is because the minimum pressure valve is not open, resulting in high pressure in the cylinder, the safety valve pressure relief protection. 

2, running computer motor overload protection. This fault is the minimum pressure valve is not opened, resulting in too high a pressure in the cylinder, the main motor load increases, the current increases, the thermal relay protection shutdown.  

3、Air compressor startup failure. This failure is the minimum pressure valve backstop is not closed tightly, resulting in the return of compressed air from the pipe network, so that a certain pressure is generated in the cylinder, resulting in the unit can not start. Air compressor in the start, the control computer detects a certain pressure in the cylinder, the unit will not start!

4、High oil pressure when unloading the air compressor. This fault is the minimum pressure valve is not closed tightly, the unit unloading network compressed air back to the cylinder pressure increases resulting in higher oil pressure, the unit increases energy consumption.