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1. Before carrying out repairs, prepare the testing tools. 2. Diagnose the fault and confirm it. Accurate judgment saves trouble. A diagnosis needs to be confirmed. 3. Troubleshoot by starting with the simple things and moving on to the more complex ones, beginning with the easier issues first. No need to disassemble; it remains intact. Vacuum pump units are used to minimize new damage caused by the lack of specialized tools and improper operation, as well as to reduce the time required for adjustments and running-in periods. Generally speaking, modular rotors are not detachable; otherwise, the geometric tolerances will be lost and the rotor will become unusable. 4. For pumps that are toxic, harmful, or corrosive, the user should first clean them and inform the maintenance personnel of the necessary protective measures to ensure their health. 5. Fault Classification Faults are divided into operational faults and performance faults. Operation faults can include the pump not running, excessive pump temperature, oil leakage, water leakage, and power levels exceeding the specified limits. Performance failures can include issues such as excessive pressure, excessive total pressure, pumping efficiency, noise, fuel injection problems, and inadequate gas suppression performance. 6. Examples of fault determination and diagnosis (1) The pump does not rotate. Since the situation is unclear, the pump should not be started yet to avoid worsening the fault. Whether it can be twisted by hand or not. ①The pump can be rotated by hand but does not spin. The reason could be a coupling failure ； Slipping ； The motor wiring is incorrect ； Motor damage ； The power source is out of battery, etc. ②It cannot be rotated or is too heavy to rotate; this may be due to the pump starting temperature being too low and the viscosity of the pump oil being too high ； Excessive oil return due to design and manufacturing issues. Excessive oil level in the water ring vacuum pump causes excessive oil return when the pump stops operating (either due to too much oil added, or water vapor condensing inside the pump, or water that has condensed in the exhaust pipe flowing back into the pump) ； There is a foreign object inside the pump (solder slag, oxides in the intake pipe) ； Debris from pump components such as disc springs ； Vane deformation and jamming ； Gearing occurred (copper sleeve, rotor, middle wall, pump cover, stator, bearing). (2) The pump temperature is too high. It refers to the high oil temperature measured near the low-stage exhaust valve, which exceeds the value specified in the user manual. As the pump temperature rises, the viscosity of the pump oil decreases significantly, and its saturated vapor pressure increases, which leads to an increase in the pump’s maximum pressure and a decline in its pumping efficiency ； Makes rubber parts age more easily ； Thermal expansion reduces the operating clearance, especially the clearance in the thickness direction of certain non-metallic vanes and within the inner bore of the copper sleeve, which affects the reliability of pump operation. The reasons for too high pump temperature can include excessive pump temperature, high intake air temperature, a failed intake air cooling system, or excessively high inlet pressure due to the pump operating continuously for long periods ； The water cooling pump does not provide sufficient cooling water volume, and the design of the circulating water system is inadequate ； Failure of the temperature-controlled water flow control valve, etc. (3) Oil leakage. It can occur at the shaft seals, the sealing surfaces of the oil tank and pump components, the drain plugs, oil level gauges, oil hole plugs, the connections between the stator components and the supports, as well as in devices such as air control valves (e.g., 2X-8). It can be caused by seal aging, improper installation, damage or failure, uneven surfaces, impurities, roughness, and loose casting. If oil returns after the pump is stopped, it will enter the air lock valve; failing to close the air lock valve may cause oil leakage. When making custom rubber gaskets, it is essential to use oil-resistant rubber, and they must be made in accordance with the original design shape; if the sealing surface is too large, it won’t fit tightly and oil leakage will occur. (4) Leaks can occur at water pipe joints, the surface of the water jacket cover, the plug of the drain hole, the drain valve, etc. Penetrations in the water jacket, casting defects, and frost cracking can also cause leaks. (5) Excessive high power. It can be caused by factors such as excessively high inlet pressure due to continuous operation over a long period, excessively high discharge pressure, damage resulting from the entry of foreign objects, excessively high pump temperature, too small clearance between the rotating vanes and other components, excessively high voltage, and too much liquid returning back into the pump – all of which can lead to motor damage. Long-term continuous operation in the vicinity of high power levels should be avoided as much as possible. If there is sediment on the surface, it should be removed regularly by taking it apart. (6) The ultimate pressure does not meet the standard. It can be caused by external leaks, internal leaks, blocked oil holes, poor quality or contaminated oil, the presence of condensable substances such as water vapor, instrument distortion, and abnormal pump operation. When a 2x rotary vane vacuum pump has frequent leakage problems, white vapor can be seen at its exhaust port. There are many bubbles at the fuel gauge, and exhaust pressure can be felt with the hand on the exhaust port. There are many bubbles on the oil surface at the low-level exhaust valve. The power will increase slightly. At this time, the first thing to check is whether the gas damping valve is properly closed. Since the ultimate pressure is measured at the pump outlet for each new pump upon leaving the factory, in the event of any leakage, the pump outlet as well as the pipes, valves, and containers should be checked one by one. Failed outer shaft seal, lack of oil in the oil cup, and air leakage due to blocked oil holes can also cause external leakage. Internal leakage can be caused by the moving clearances within the pump, the surface of the exhaust valve seat, the sealing surface of the exhaust valve, the internal shaft seal, the surface of the pump cover, the intake pipe, and the seals of the air release valve. Wear, corrosion, and seizure can increase the operating clearance. When the oil vent is blocked, open the fuel filling port and listen; the noise of the pump will be lower. If, with a well-sealed fuel tank, your hand feels pulled at the exhaust port, the exhaust valve may be faulty. If the pump oil is clean and the pump has been stored unused for a long time, an air release valve can be used to remove moisture from within the pump. If it doesn’t work, check the instrument. If the pumped oil is yellowish or whitish and has emulsified, the air purge can be turned up to full volume; adjusting the amount of air used for purification will help facilitate the cleaning process. If necessary, an appropriate amount of air can be introduced at the pump inlet to speed up the purification process. If other volatile gases or liquids are drawn in, the oil should be changed promptly; if necessary, the fuel tank should be cleaned. In some pumps, pump fluid accumulates in the inter-stage air passages; to achieve good oil change results, it is necessary to remove this accumulated pump fluid.