Mechanical And Electrical Maintenance Methods For Sanitary Rotary Lobe Pumps

The maintenance method of Sanitary Rotary Lobe Pump is: dismantle the shielded pump: clean each part first, and then check them for abnormalities. Then measure the dimensions of key parts and conduct electrical inspection of the motor winding.

1. Mechanical inspection
1. Measure the aperture of the graphite bearing and the shaft diameter of the sleeve, and check the finish of their mating surfaces. If the fit clearance between the graphite bearing and the sleeve exceeds the requirements of the maintenance standard (0.55-11kw fit clearance, diameter difference is 0.4㎜, 15-45kw fit clearance, diameter difference is 0.5㎜) or the finish of the mating surface is poor, the bearing, sleeve or thrust plate needs to be replaced according to the situation.
2. Measure and check the upper and lower outer stoppers of the impeller and the sizes of the buckle rings and the inner diameter of the pump seat that match them. Whether these two fit clearances are within the range specified in the maintenance standard, if they are out of tolerance, parts need to be replaced or other measures (such as: surfacing, sleeve inserts) need to be taken to make the fit clearance meet the specified requirements. Otherwise, it will affect the performance, flow, head, axial balance force, etc. of the pump.
3. Observe and check the appearance of the stator and rotor shielding sleeves, especially pay attention to whether there are any abnormal conditions at the welds. If necessary, flaw detection and leak detection should be performed.
4. After long-term operation, the balance of the rotating part may change. Therefore, it is necessary to assemble the rotor together with rotating parts such as the impeller for dynamic balancing test.
2. Electrical inspection
1. DC resistance inspection: The imbalance of the three-phase resistance shall not exceed 2%.
2. Insulation resistance inspection: The insulation resistance of the shielded pump motor winding can generally reach more than 100MΩ. If it is lower than 5MΩ, the reason needs to be analyzed, whether the insulation is damp, or whether the shielding sleeve has leakage points, etc. If there is no problem with the stator shielding sleeve leakage detection, it is purely insulation dampness, and drying treatment is required. If there is a problem with the stator shielding sleeve, the shielding sleeve needs to be replaced.