Maintenance of Roots vacuum pumps, common causes of failures, and methods to address them
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I. Maintenance and Care1. Daily inspections:
(1) Oil level check: An excessive oil level can cause temperatures to rise, while a low oil level results in poor lubrication. (2) Temperature check: Use a thermometer to check the temperature of various areas. (3) Motor load check: Measure the motor load using a wattmeter or ammeters and voltmeters. 2. Monthly inspection: The tension of the coupling elastomer or triangular belt. 3. Quarterly inspections ； Has the lubricating oil in the gearbox deteriorated? 4. Semi-annual inspection: (1) Check whether the lubricating oil in the front cover bearing housing has deteriorated. (2) Whether the seal is damaged. 5. Annual inspection: (1) Check whether the bearings are worn. (2) Whether the piston rings and piston ring bushings are worn. (3) Whether minor wear of the gears affects the proper operation of the rotor, and whether adjustments are necessary. II. Causes of Faults and Methods to Eliminate Them
Causes of faults and methods to address them:
Limiting pressure not reached:
1. Leaks in pipes or the system.
2. Leaks in the pump.
3. Decreased limiting pressure of the pre-pump.
4. Lubricant is too dirty or of the wrong type.
5. Worn oil seals.
Solutions:
1. Inspect for leaks in the system.
2. Inspect the pump for leaks.
3. Repair or replace the pre-pump.
4. Replace the lubricant.
5. Replace the oil seals.
Insufficient pumping speed:
1. Insufficient capacity of the pipe passages.
2. Decreased pumping speed of the pre-pump.
Solutions:
1. Increase the capacity of the pipe passages.
2. Repair or replace the pre-pump.
Motor overload:
1. Excessively high inlet pressure.
2. The rotor’s end face makes single-contact with the end cover.
3. Backflow from the pre-pump enters the rotor chamber of the Roots vacuum pump.
Solutions:
1. Adjust and control the inlet pressure.
2. Adjust the gap at the rotor’s end face.
3. Install equipment to prevent backflow.
Overheating:
1. The pre-pump selected has insufficient pumping speed, resulting in an excessive compression ratio.
2. Excessively high inlet pressure.
3. Poor cooling.
4. Excessive lubricant in the gearbox.
5. Contact between the rotor and the pump casing.
6. Poor lubrication of gears, bearings, and oil seals.
Solutions:
1. Select a different pre-pump.
2. Adjust and control the inlet pressure.
3. Ensure proper flow of cooling water and increase its volume.
4. Adjust the amount of lubricant used.
5. Make necessary repairs.
6. Ensure adequate lubrication.
Abnormal noises:
1. Improper assembly.
2. Misalignment of the guide gears and the rotor, causing collisions between them.
3. Excessively high inlet pressure.
4. Overload or poor lubrication leading to damage to the gears.
5. Worn bearings.
Solutions:
1. Reassemble the components.
2. Adjust the positions to ensure proper gaps.
3. Adjust and control the inlet pressure.
4. Replace the gears.
5. Replace the bearings.
Severe premature wear of bearings and gears:
1. Poor quality of lubricant.
2. Insufficient amount of lubricant.
Solutions:
1. Replace the lubricant.
2. Add more lubricant