Overload issues

The power required for the roots vacuum pump to compress the gas is directly proportional to the pressure difference, once the gas pressure difference is too high, the pump may be overloaded, causing the motor windings to burn out. There are several ways to solve the problem of pump overload:

(1) Adopt mechanical automatic pressure regulating bypass valve. The bypass valve is installed on the bypass line between the outlet and the inlet of the roots vacuum pump. This valve controls the differential pressure between the inlet and outlet of the pump not exceeding the rated value. When the differential pressure reaches the rated value, the valve automatically opens by the differential pressure effect, so that the outlet and the inlet of the roots vacuum pump are connected, so that the pressure difference between the inlet and outlet is rapidly reduced, and the roots vacuum pump works under the load of almost no differential pressure. When the differential pressure falls below the rated value, the valve closes automatically and the gas is pumped away by the backing pump through the roots vacuum pump. The roots vacuum pump with bypass relief valve can be started at the same time as the backing pump, making the unit easy and convenient to operate.

(2) Hydraulic coupling is adopted. The use of hydraulic couplings can also prevent the overload of the pump, so that the pump can work at high differential pressure. The hydraulic coupling is installed between the pump and the motor. Under normal working conditions, the hydraulic coupling transmits the rated torque from the end of the motor to the pump. The maximum differential pressure of a roots vacuum pump is determined by the maximum torque transmitted by the hydraulic coupling, which is regulated by the amount of liquid in it. When the pump works under high differential pressure or starts at the same time as the backing pump, there is a speed difference inside the liquid coupling, that is, sliding, and only a certain torque is transmitted to slow down the pump. As the pumping progresses, the gas load decreases and the roots vacuum pump gradually accelerates to the rated speed.

(3) Vacuum electrical components are used to control the inlet pressure of the pump. Pressure-sensitive components such as vacuum cassettes, relays or electrical contact vacuum pressure 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 a given value (the allowable starting pressure of the pump), the pressure sensitive element sends a signal to open the roots vacuum pump through the electrical control system (if the vacuum system is equipped with a roots vacuum pump bypass pipeline, the bypass line valve is closed at the same time). If the inlet pressure of the pump is higher than the specified value, the roots vacuum pump will be automatically shut down (or the pump bypass line valve will be opened at the same time), thus ensuring the reliable operation of the roots vacuum pump.