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I. Smoking and oil spraying in vane vacuum pumps: This refers to the occurrence of smoking or oil spraying at the exhaust port of a vane vacuum pump during operation. 1. Smoking: If smoking occurs when the pump just starts running, it is normal; however, if it continues to smoke for an extended period, it is abnormal. Solution: Smoking indicates that there is a need for repairs outside the pump’s air intake, including the pipes, valves, and containers. After leak detection and repair, the smoking will stop. 2. Fuel spraying indicates that there are numerous leakage points outside the air intake, or even that the air intake is exposed to the atmosphere. Solution: Seal the air inlet of the pump and run it; if no fuel is sprayed, there is a leak. The exhaust valve seat may be damaged – check it and replace any damaged exhaust valve seats. II. Decline in the vacuum level of vane vacuum pumps: This refers to the situation where the measured vacuum level of a vane vacuum pump is lower than the specifications provided at the time of manufacture or than the vacuum level it had when used previously. The reasons for the low vacuum level are as follows. 1. The oil passage inside the pump is blocked or obstructed, and a sufficient amount of oil is not retained in the pump chamber. Solution: Check whether the oil circuit is unobstructed, and add vacuum pump oil of the same type. 2. Increase the clearance for fitting. This is due to the long-term presence of dust and other particles in the evacuated gas, which causes wear between the rotor vanes and the stator and thus an increase in the gap. Solution: Check if the gap is too large, and replace with new parts. 3. The grade of the rotary vane vacuum pump oil added this time is different from the original one. Different vacuum pump oil grades yield different results, as the saturated vapor pressures of oils in various grades vary. Solution: Replace it with the correct new vacuum pump oil according to the product’s model specifications. 4. The temperature of the gas being evacuated may be too high. Solution: Lower the temperature of the gas being evacuated, or a corresponding heat exchanger can be added. 5. Another reason for low vacuum levels is also the vacuum pump oil – it may become emulsified and change color, or it may be too dirty. Solution: Drain all the vacuum pump oil from the pump, replace it with the same type of vacuum pump oil, and prevent water vapor and impurities present in the gas to be pumped from entering the pump.