| Roots vacuum pump (referred to as roots pump for short) is a non-internal compression type rotary positive displacement pump, which achieves suction and exhaust by two 8-shape rotors rotating in the pump shell. Its principle is similar with roots blower. As it works within the low pressure range, the free paths of the gas molecules are long, and the resistance is strong for gas to pass through small gaps, thus, it is able to obtain a higher compression ratio, and can be used as a booster vacuum pump; But it can not directly exhaust the gas into the atmosphere alone, and it shall be connected with a fore vacuum pump in series, and exhaust the pumped gas into the atmosphere through the fore vacuum pump. Features 1. There is a certain gas between the rotor and pump chamber, and between rotors. They do not contact with each other, and do not need oil lubrication. 2. Rotor has a good geometric symmetry, and can improve the rotary speed so as to produce a compact large pumping rate pump. 3. Pump works with small vibration and large capacity, and the capacity utilization factor is around 0.5. 4. In the pump chamber, there is no compression as the mechanical vacuum pump does, so it does not require an exhaust valve. For this reason, it can be used to pump the condensable vapors. 5. It starts fast, and can achieve the ultimate vacuum in a short period. It has low power and low maintenance cost for operation. 6. Roots pump owns a high pumping rate in a wide range of pressures (1000Pa ~ 1Pa). It is able to quickly exhaust the gases which are suddenly released of gas, and cover the shortage of low pumping rate of the diffusion pump and oil sealed mechanical pump under the pressure of (1000Pa ~ 1Pa). As a result, it is most suitable used as a booster pump. Applications ZJ series roots vacuum pump is a kind of rotary positive displacement pump, which must be used with a fore pump. It has a higher pumping rate in a wider pressure range, and not sensitive to the pumped gases which contain dust or water vapor. Therefore, it is widely used in the metallurgy, chemical industry, food, electronic coating and other industries. |
