Once there is a gap in the internal parts of the Roots vacuum pump, it will not only cause the parts to loosen, but also lead to the deposition of debris and blockage, which will reduce the working efficiency of the equipment and increase the loss rate. Therefore, when it is found that there is a gap in the equipment, it must be adjusted in time to keep the equipment in a good installation state.

1. Adjustment of radial clearance of Roots vacuum pump
It is inconvenient to measure the radial clearance directly, but you can listen to the friction sound between the rotor and the casing after running for a certain time at the rated speed or higher speed. When adjusting, you can loosen the connecting screws of the two end covers and pull out the pins. Use the end cover to adjust, and then hinge the locating pin holes of the end cover and the pump casing, re-mark the locating pin, and of course, tighten all the screws first.

2. Adjustment of meshing gap between rotor profiles of Roots vacuum pump
Adjusting the meshing clearance of the rotor is essentially adjusting the synchronous gear, that is, pulling out the taper pin from the hub of the driven gear, loosening the screw in the waist-shaped slot, and slowly turning the driven rotor while turning. Measure the gap between the two rotors until the adjustment meets the requirements, then tighten the screws in the waist-shaped holes, re-ream the pin holes, and install the positioning pins.

3. Adjustment of axial clearance of Roots vacuum pump
The axial clearance is the clearance between the rotor end face and the left and right end covers. The gap can be adjusted by the thickness of the grinding adjustment pad and the thickness of the end face sealing paper pad.

The vacuum pump startup is a light-load startup for the prime mover. For some large units, it is difficult to start the unit with large inertia. If you don't pay attention to the startup method, it will damage the power grid or the motor. Therefore, corresponding attention should be paid to the starting characteristics of different forms of pumps.

(1) Zero-flow start-up characteristics of centrifugal pumps - valve-off start
The shaft power of the centrifugal pump is small in the zero flow condition, so the startup characteristic of the centrifugal pump is zero flow startup. After the pump reaches the rated speed, the discharge valve can be adjusted to the rated point of flow.
(2) Large flow start-up characteristics of axial flow pump - full-open valve start
The shaft power of the axial flow pump is high when the flow is zero, and the power is the smallest when the flow is high. Therefore, in order to reduce the starting current, the starting characteristic of the shaft power should also be the starting with a large flow.
(3) Start-up characteristics of mixed-flow pump - full-open valve start
The shaft power of the mixed-flow pump is between the above two kinds of pumps in the zero flow condition, so the starting characteristics of the mixed-flow pump should also be between the two of the above two kinds of pumps, and the valve is fully opened to start.
(4) Start-up characteristics of the vortex pump - full-open valve start
The shaft power of the vortex pump is high in the zero flow condition, so similar to the axial flow pump, the start-up characteristic of the vortex pump should also be the start of a large flow.