The ultimate vacuum of a Roots vacuum pump depends on the ultimate vacuum of the preceding pump in addition to the structure and manufacturing accuracy of the pump itself. There is a certain gap between the rotors, and between the rotors and the inner wall of the pump casing. In order to improve the ultimate vacuum of the pump, Roots pumps can be used in series. The working principle of the Roots vacuum pump is similar to that of the Roots blower, and it can operate at high speed, so let's learn more about the working principle and structure of the Roots vacuum pump together!
Roots vacuum pump working principle:
The position of the two rotors of the Roots vacuum pump in the pump body determines the overall structure of the pump. The overall structure of the domestic and foreign Roots vacuum pump is generally arranged in three programs
1. Vertical: the two rotors are installed horizontally on the axis, and the supply and exhaust ports of the pump are set horizontally in this structure, which is convenient for assembly and piping connection. However, due to the high center of gravity of the pump, the disadvantage of poor stability in high-speed operation, except for small-size pumps, the plane formed by two rotor axes is perpendicular to the horizontal plane, and it is not common to adopt this structural type.
2. Horizontal: the two rotor axes are installed horizontally, and the exhaust port is below the pump. The exhaust port below is generally connected horizontally, so the inlet and outlet directions are perpendicular to each other. The exhaust port is connected to a three-way pipe with a two-way opening, which is used when one end is connected to the exhaust pipe and the other end is connected to a death or bypass valve. This structure is characterized by a low center of gravity and good stability when driving at high speeds. The plane formed by the axes of the two rotors is horizontal. This structure of the pump's air intake in the pump above, domestic and foreign large and medium-sized pumps are mostly used in this structural type.
3. Longitudinal axis type: foreign Roots vacuum pump has two rotor axes installed perpendicular to the horizontal plane. The lubrication device is also complex. After the overall structure is determined, the structure of the assembly gap is easy to control, the rotor assembly is convenient, covers an area of small, but the gears and other transmission institutions are inconvenient to dismantle and install, the structure and shape of the pump body itself is also determined accordingly.
4. Roots vacuum pump with relief valve: In order to prevent accidents caused by overloading, Roots pumps are installed with more reliable safety protectors. In other words, a relief valve is installed in the bypass line. The relief valve closes when the exhaust port is at the specified pressure. When the pressure at the exhaust port is normal, the relief valve closes again on its own. Due to the automatic adjustment and the permissible differential pressure of the pump, the relief valve has the great advantage of enabling the Roots pump to be operated continuously over a wide range of pressures together with the predecessor pump. With this design, when the pressure at this exhaust port exceeds the specified pressure, the valve of the relief valve is automatically pushed open and overflow occurs, which can shorten the exhaust stopping time of the vacuum vessel in rough vacuum by 30~50%. For larger pumps, the relief valve is installed in the bypass pipe on the outside of the pump body; for smaller pumps, the relief valve is installed in the pump casing.
5. Roots vacuum pumps with steam condenser: When pumping steam, the pumping unit needs to be designed with a condenser to condense the steam. The condenser can be installed before or after the pump and cannot be installed on the pump body of the Roots vacuum pump. In some cases, the condenser sublimation heat absorption can reduce the heat generation of the Roots pump. Assuming a compound condenser is used, maintenance can be done with a suitable solvent to remove dirt, and steam can flow smoothly through the conduit.
The above introduction is the working principle and structure of Roots vacuum pump detailed, for more information, feel free to contact us!
