Roots vacuum pump ( in short as roots pump) is a kind of no in the rotation of the compressed variable capacitance type vacuum pump.also there have roots liquid ring vacuum system and roots piston vacuum system ,roots vacuum pump Is the use of two figure 8 rotor spinning in the pump casing and suction and exhaust.The principle and the roots blower is similar.Due to its work in the low pressure range, degree of freedom of gas molecules is larger, the gas leakage through the tiny crack resistance is very big, therefore can obtain higher compression ratio, can be used as a booster vacuum pump;But it can’t separate to gas directly into the atmosphere, need level and the former vacuum pump series, gas is pumped through the level before the vacuum pump into the atmosphere.
Roots pump features are: 1. The rotor and the pump cavity, there is a certain gap between rotor and rotor, contact each other, don’t need lubricating oil.2. The rotor with good geometrical symmetry, can improve the speed, so that they can produce the compact structure of the large pumping speed pump.3. The little vibration when the pump work, large volume, capacity utilization factor = 0.5 or so.4. In the pump chamber is not like a mechanical vacuum pump compression occur, so it does not need to vent.And so, pumping condensable vapor.5. Start fast, can achieve in a short time limit vacuum.Small power, low operation maintenance cost.6. Roots pump in a wide range of pressure (1000 pa ~ 1 pa) have a large pumping speed, can quickly get rid of all of a sudden release of gas, make up for the diffusion pump oil seal and mechanical pump pumping speed when the 1000 pa ~ 1 (pa) are small defects.Therefore, it is most suited to make a booster pump.
Work, gas is pumped from the inlet to between the rotor and the pump body, then a rotor and the pump body to separate gas and air inlet, were separated by gas (as shown in figure today part), in the process of continuously rotating rotor, was sent to vent.Space is in a closed state, so there is no compression and expansion.But when the rotor’s peak of edge to vent, because of part V of the pressure of low pressure than the vent, in order to make the connected volume uniform pressure, gas will spread to the V from vent area, the direction of diffusion and rotor rotating in opposite directions.Again as the rotor turns, gas compression of V place to vent to discharge it.At this time the other side of the rotor are connected to the air inlet part in gas, when the rotor rotates unceasingly, repeat the above extraction process continuously discharge flow in the gas.This process is equivalent to the rotor space by a certain minimum value increased to the maximum, and then by the maximum reduce to the minimum.This is the volume effect principle of roots vacuum pump.
Roots vacuum pump under the condition of inlet pressure is very low, because of the high rotor speed, linear velocity close to the thermal motion of molecules on the surface of the rotor speed, when the collision on the rotor of the gas molecules are pushed to the high pressure rotor of vent, be fore pump out.This is the principle of molecular roots vacuum pump.
Roots vacuum pump is widely used in vacuum metallurgy industrial , vacuum degassing, vacuum smelting, steel vacuum processing, and spatial simulation, such as low density wind tunnel smoke unless the corrosive gas in the device.Can also be used in chemical, food, medicine, machine manufacturing industry, such as distillation, evaporation, drying process