I. Common faults of vacuum pumps fall into the following categories:
① Reduced vacuum level;
② Pump fails to operate normally or even seizes up;
③ Excessive noise or abnormal sounds during operation;
④ Poor pump body sealing—oil leakage;
⑤ Significant spraying of oil droplets and mist upon startup, polluting the environment;
⑥ Difficulty starting.
The table below lists common malfunctions of the vacuum pump, their causes, and the corresponding remedies.
II. Malfunction Causes and Remedies
(I) Causes of low vacuum levels (Note: remedies are in parentheses):
1. Insufficient oil level (change oil)
2. Oil is dirty or emulsified (change oil)
3. Incorrect oil grade or mixed oils; use of oil with excessively low viscosity in summer (change oil)
4. Air leakage (check shaft seals, exhaust valves, end covers, the intake port, etc.)
5. Excessive clearances or presence of wear and scratches (check sealing conditions and repair/replace seal rings; check clearances between the pump chamber, rotor, vanes, and end cover plates; remove debris and impurities; refinish/grind components to meet precision specifications)
6. Oil passage obstructed; insufficient oil retained in the pump chamber (adjust oil inlet flow; use high-pressure air to clear oil passages and remove deposits during cleaning).
7. Excessive temperature rise during operation, causing pump oil to thin, sealing performance to deteriorate, and oil vapor pressure to increase (circulate cooling water to lower temperature; check clearances and repair to meet precision specifications).
8. Excessive interference fit during installation of the intermediate partition, causing the pump chamber to bulge/deform and leading to air leakage (refinish the pump chamber, replace the pump, or scrap the unit).
9. Damaged exhaust valve reed resulting in poor sealing (repair or replace the valve reed).
10. Improper assembly; uneven tightening of end cover screws, causing rotor axis displacement (reassemble).
11. Poor vane movement (refinish the mating surfaces of the rotor and vanes; replace springs)
12. Temperature of the pumped gas is too high (install a cooling device to cool the gas before it enters the pump)
13. Intake filter screen is clogged (remove the intake filter screen, clean and dry it, then reinstall)
14. Gas ballast valve gasket damaged or not tightened (replace the gasket; tighten the gas ballast valve)
(II) Vacuum pump motor is overloaded or fails to rotate, resulting in a "seized" condition
(Note: troubleshooting methods are in parentheses):
1. Damaged spring causing uneven force on the vane (replace the spring)
2. Improper assembly causing localized stress (reassemble)
3. Damaged filter screen allowing external debris (such as metal chips or particles) to fall into the pump chamber (disassemble and inspect the pump; clean; reinstall the filter screen)
4. End-face clearance is too small, causing excessive pump temperature rise (grind/refinish rotor vanes, adjust clearance)
5. Pump oil has deteriorated or formed deposits; oil viscosity is unsuitable (change oil)
6. Rotor is damaged (replace with new parts)
7. Fit between shaft and bushing is too tight; lack of lubrication (ensure forced oil lubrication)
8. Intermediate air passage is obstructed (clear the passage or replace with a thinner rubber gasket)
9. Cross-coupling on the shaft is damaged (repair or replace rotor shaft or cross-coupling)
(III) Abnormal noise during vacuum pump operation (Note: troubleshooting methods in parentheses):
1. Broken spring; impact noise from the vanes during operation (replace spring)
2. Improper assembly or loose parts causing abnormal operating noise (reassemble)
3. Debris in the pump chamber, or parts with burrs or deformation, causing operational issues (disassemble, clean, inspect, and grind/deburr)
4. Poor lubrication within the pump chamber (clear and adjust oil passages)
5. Excessive dead space (clearance volume) in the pump chamber (an inherent pump issue; shift the central partition plate by a few centimeters to reduce dead space)
6. Motor malfunction (repair or replace motor)
(IV) Vacuum pump oil leakage (Note: troubleshooting methods in parentheses):
1. Seals at the bearings, end covers, oil sight glass, oil drain port, oil reservoir, etc., are damaged or not properly seated and tightened (replace with new seals; ensure correct positioning during assembly, tighten screws, and apply uniform, appropriate pressure).
2. Leakage holes in the housing (seal the leaks).
(V) Vacuum pump oil discharge:
1. Excessive oil level (drain excess oil).
2. Sudden exposure to the atmosphere (when starting the pump, use intermittent motor activation; if exposed to the atmosphere due to system damage, close the low-vacuum valve or use a clamp).
3. Pump design features a small oil reservoir (install an oil-mist separator at the exhaust port and attach a rubber hose to the exhaust to vent away from the work area).
4. Pump rotor rotating in reverse (reconnect power supply to reverse rotation direction)
(VI) Difficulty starting the vacuum pump (Note: troubleshooting methods in parentheses):
1. Oil temperature too low (heat the oil to above 15°C; ensure the ambient temperature of the workspace is above 15°C)
2. Poor lubrication inside the pump (adjust the oil circuit to improve lubrication; replace with appropriate mechanical pump oil)
3. Oil has deteriorated or is contaminated with diffusion pump oil (replace the oil)
4. Pump chamber not vented to atmosphere upon shutdown, causing a large amount of pump oil to enter the chamber (ensure the pump is vented when stopping; check if the differential pressure valve is functioning correctly)
5. Motor missing one phase of power supply (motor makes no sound in this state) (inspect and repair the power supply)
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