The greatest advantage of roots vacuum pump is high exhaust speed under low inlet pressure. However, the pump must be connected with a backing vacuum pump since the roots pump cannot work until the backing pump vaccumizes the pumped system to the allowed inlet pressure of the roots vacuum pump. Moreover, the roots vacuum pump cannot tolerate large pressure difference; otherwise, the pump will be damaged by overload and superheating. Therefore, a suitable backing pump and safety devices are indispensible for the roots vacuum pump.
The backing pump can be vacuum pump like slide valve pump, rotary vane pump, water ring pump or oil ring pump. The water ring pump is ideal for gas with too much steam. The roots pump runs quietly owe to precision gears. The internal ZJP overflow valves allow the roots vacuum pump and backing pump to start synchronously in atmosphere, shortening exhaust time. The vibration is extremely low because of perfect dynamic balance generated by discharge flange and suction flange which meet international standards. High exhaust speed can be obtained in medium vacuum, thus running cost is lowered. The clearances between rotators and between the pump body and rotators are strictly controlled to avoid frictions between moving parts in the pump cavity. All the flange parts are sealed by O rings instead of flat organic silicon rubber, making maintenance more convenient. Service life of the pump is greatly prolonged by well-chosen bearings and satisfactory lubrication. No lubricant exists in the pump cavity to ensure the dryness.
Max. zero flow compression ratio
Max. tolerant differential pressure