How to solve the overload phenomenon of the Roots vacuum pump

The power required to compress the gas from the Roots vacuum pump is proportional to the pressure difference. Once the gas pressure difference is too high, the pump may be overloaded, causing the motor winding to burn. The main methods to solve the pump overload problem are as follows:

(1) A mechanical automatic pressure regulating bypass valve is used. The bypass valve is mounted on the bypass line between the outlet and the inlet of the Roots vacuum pump. This valve controls the differential pressure between the pump inlet and outlet to not exceed the rated value. When the differential pressure reaches the rated value, the valve is automatically opened by the differential pressure, so that the outlet of the Roots vacuum pump communicates with the inlet, so that the pressure difference between the inlet and outlet is rapidly reduced, and the Roots vacuum pump operates under almost no differential pressure. When the pressure difference is lower than the rated value, the valve is automatically closed and the gas is pumped away by the foreline pump through the Roots vacuum pump. The Roots vacuum pump with bypass relief valve can be started at the same time as the foreline pump, making the unit easy to operate.

(2) Use a hydraulic coupling. The use of a hydraulic coupling also prevents overloading of the pump, allowing the pump to operate under high pressure differentials. The hydraulic coupling is mounted between the pump and the motor. Under normal operating conditions, the hydraulic coupling transmits the rated torque from the motor end to the pump. The maximum differential pressure of the Roots vacuum pump is determined by the maximum torque transmitted by the fluid coupling, and the maximum torque that the hydrodynamic coupling can transmit is regulated by the amount of liquid in it. When the pump works under the high pressure difference or starts at the same time as the foreline pump, the speed difference is slipped inside the liquid coupling, and only a certain torque is transmitted to make the pump decelerate. As the pumping progresses, the gas load decreases and the Roots vacuum pump gradually accelerates to the rated speed.

(3) Use vacuum electrical components to control pump inlet pressure. Pressure sensitive components such as vacuum bellows relays or electrical contact vacuum gauges are placed at the inlet line of the Roots vacuum pump. After the vacuum system is started, when the pressure at the inlet of the Roots vacuum pump is lower than the given value (the pump allows the starting pressure), the pressure sensitive component sends a signal, and the Roots vacuum pump is turned on via the electrical control system (if the vacuum system is equipped with a Roots vacuum pump) Pass the line and close the bypass line valve). If the pump inlet pressure is higher than the specified value, the Roots vacuum pump is automatically turned off (or the pump bypass line valve is opened at the same time), thus ensuring reliable operation of the Roots vacuum pump.