Common faults and solutions of rotary vane vacuum pump

Rotary vane vacuum pump is one of the basic vacuum equipment in vacuum technology Rotary vane pumps are mostly small and medium-sized pumps There are two types of rotary vane vacuum pump: single stage and double stage The so-called two-stage is to connect two single-stage pumps in series in the structure Generally, they are made into two-stage ones to obtain higher vacuum In order to prevent oil injection due to oil return and reversal, the pump port shall be opened first, and the oil stored in the pump shall be manually turned into the oil tank according to the regulations Check the oil level at the same time It should be above the center of the oil level indicator, but it should not be full of the oil level indicator If there is too much, it should be discharged Assistant method for judging steering Put the sheath upside down on the pump port If it is sucked after starting the pump, it is positive, blown down and reverse Normal sound is positive, abnormal sound is reverse It is suggested to divide the faults into operation faults and performance faults Operation failure can include pump not running, pump temperature too high, oil leakage, water leakage, power over standard, etc Performance failure may include limit pressure, limit full pressure, air extraction efficiency, noise, fuel injection, gas ballast performance, etc which are not up to standard or fail to meet the requirements If the condition is not clear, the pump cannot be started first to avoid aggravating the fault Can and cannot be turned by hand A The pump can be turned without turning The causes can be coupling failure, belt slipping, wrong motor wiring, motor damage, power failure, etc The reason why it can't be turned or heavy can be that the starting temperature is too low and the viscosity of pump oil is too high; there are too many pump stops and oil returns due to design and manufacturing reasons Too much oil is returned due to too high oil level (too much oil is added, or water vapor condenses in the pump, or water flows back to the pump due to condensation in the exhaust pipe); there are foreign matters in the pump (welding slag and oxide in the air inlet pipe; debris of the pump parts such as the vane spring); the vane is deformed and stuck; there is occlusion (copper sleeve, rotor, middle wall, pump cover, stator, bearing) The pump temperature is too high It means that the oil temperature measured near the low-level exhaust valve exceeds the value specified in the operation manual As the pump temperature increases, the viscosity of the pump oil will be greatly reduced, and the saturated steam pressure of the right to use pump oil will be increased, the ultimate pressure of the pump will be increased and the pumping efficiency will be reduced; the rubber parts will be easy to age; the thermal expansion will make the operation reliability The reasons for the high temperature of the pump can be that the ambient temperature of the pump is too high, the air inlet temperature is too high, the air inlet cooling device fails, the pressure of the pump in the long-term continuous operation is too high; the cooling water quantity of the water-cooled pump is insufficient, the design effect of the circulating water is not good; the temperature control water quantity regulating valve fails, etc Oil leakage It can occur in the sealing surface of shaft seal, oil tank and pump parts, oil drain plug, oil mark, oil hole bulkhead, through-hole connection of stator part and support, air ballast valve (such as 2x-8), etc It can be caused by aging of seals, improper installation, damage and failure, uneven surface, impurities, roughness and loose castings If the oil returns after the pump is stopped, the oil will enter the gas valve, and oil may leak if the gas valve is not closed When making the self-made rubber pad, oil resistant rubber must be used It should be in accordance with the original design shape If the sealing surface is too large, it will leak oil if it is not pressed tightly Water leakage can occur at the water pipe head, water jacket cover plane, drain hole plug, drain valve, etc., water jacket drilling through, casting defects, frost crack, may also lead to water leakage The power exceeds the standard It can be caused by too high inlet pressure, too high exhaust pressure for long-term continuous operation, seizure of debris entering, too high pump temperature, too small matching clearance, too high voltage, too much pump fluid returning into the pump, etc., which will damage the motor Long term continuous operation near the power shall be avoided as far as possible If there is sediment on the surface, it should be removed regularly Limit pressure is not marked It can be caused by external leakage, internal leakage, oil hole blockage, poor quality of pump oil or pollution deterioration, water vapor and other condensable substances, distortion of instruments and meters, abnormal operation of pump, etc When there is much leakage, white steam can be seen at the exhaust port There are many bubbles at the oil mark, and the hand feels the exhaust pressure on the exhaust port There are many bubbles on the oil surface at the low-level exhaust valve Power will increase At this time, first check whether the gas ballast valve has been closed Since the limit pressure of each new pump is measured at the pump outlet, if there is any leakage, check the pump outlet, pipeline, valve and container one by one The failure of the outer shaft seal, the lack of oil in the oil cup and the air leakage in the oil hole can also cause the outer leakage The internal leakage can be caused by the wear, corrosion and engagement of the movement clearance in the pump, the plane of the exhaust valve, the sealing surface of the exhaust valve, the inner shaft seal, the plane of the pump cover, the air inlet pipe, and the sealing parts of the air ballast valve, which will increase the operation clearance When the oil hole is blocked, open the oil filling hole and listen to it The noise of the pump will be lighter Under the condition that the oil tank is sealed well, if the hand feels sucked on the exhaust port, the exhaust valve may fail If the pump oil is clean and unused after long-term storage, open the gas control valve to purify the water vapor in the pump If not, check the instrument If the pump oil turns yellow and white and has been emulsified, fully open the gas ballast, adjust the air ballast for purification operation, and if necessary, put a proper amount of gas into the pump port for operation, so as to speed up the purification process If other volatile gas or liquid is pumped in, the oil shall be changed in time, and the oil tank shall be washed if necessary Some pumps will deposit pump fluid in interstage airway In order to achieve good oil change effect, it is necessary to try to discharge the deposited pump fluid The ultimate pressure is measured by a compression type mercury vacuum gauge When using the calibrated thermocouple vacuum gauge and other full pressure gauges, the measured value will increase Note that the gauge of thermocouple vacuum gauge should be calibrated in pairs It is recommended to reserve a gauge calibrated at the same time for comparison in case of suspected contamination and distortion of the gauge.