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How to Solve Overload of Roots Vacuum Pump

The power required by Roots vacuum pump to compress gas is proportional to the differential pressure. Once the differential pressure of gas is too high, the pump may overload, resulting in motor winding burning. What are the main methods to solve the problem of pump overload?

1. Adopt mechanical automatic pressure regulating bypass valve.

The bypass valve is installed in the bypass pipeline between the outlet and the inlet of Roots vacuum pump. The pressure difference between the inlet and outlet of this valve control pump does not exceed the rated value. When the pressure difference reaches the rated value, the valve opens automatically by the pressure difference function, which makes the outlet and inlet of Roots vacuum pump communicate, and makes the pressure difference between the inlet and outlet decrease rapidly. At this time, Roots vacuum pump works under almost no pressure difference load. When the pressure difference is lower than the rated value, the valve closes automatically and the gas is pumped out by the front pump through the Roots vacuum pump. Roots vacuum pump with bypass relief valve can start at the same time with the front pump, which makes the operation of the unit simple and convenient.

2. Use hydraulic coupling.

Hydraulic coupling can also prevent the overload of the pump, so that the pump can work under high pressure difference. The hydraulic coupling is installed between the pump and the motor. Under normal working conditions, the hydraulic coupling transmits rated torque from the motor end to the pump. The maximum pressure difference of Roots vacuum pump is determined by the maximum torque transmitted by the hydraulic coupling, and the maximum torque transmitted by the hydraulic coupling is regulated by the amount of liquid in it. When the pump works under high pressure difference or starts at the same time with the front pump, the speed difference, i.e. sliding, occurs inside the liquid coupling, which only transmits a certain moment to slow down the pump. As the pumping proceeds, 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 elements such as vacuum diaphragm relay or electric contact vacuum gauge are installed at the entrance pipeline of Roots vacuum pump. After the vacuum system is started, when the pressure at the entrance of Roots vacuum pump is lower than the given value (the allowable starting pressure of the pump), the pressure sensor sends out a signal and opens the Roots vacuum pump through the electrical control system (if the vacuum system is equipped with the Roots vacuum pump bypass pipeline, the bypass pipeline valve is closed at the same time). If the inlet pressure of the pump is higher than the prescribed value, the Roots vacuum pump will be automatically closed (or the bypass pipeline valve of the pump will be opened at the same time), thus ensuring the reliable operation of the Roots vacuum pump.

ZJP Roots Vacuum Pump

model		ZJP- 70	ZJP- 150	ZJP- 300	ZJP- 600	ZJP- 1200	ZJP- 2500
Pumping speed（L/s）		70	150	300	600	1200	2500
Ultimate pressure （Pa）		5×10-2 （1stage piston pump as backing pump)
		1×10-1 (2 stage piston pump as backing pump)
Diff. pressure at overflow valve （Pa）		4×103			2. 7×103
Motor rotary speed（RPM）		3000
Suitable motor power（kW）		1.1	2.2	4	7.5	11	22
Flange size	inlet（mm）	80	100	150	200	250	320
	outlet（mm）	80	100	150	200	200	320
Cooling water consumption（L/h）		120			150		200
Allowable temperature（℃）		100
Vacuum pump oil		100#
Weight(without motor)（kg）		110	205	265	780	880	1350