Addtime： 2020-07-18 Browse times： 2701
What are the faults of rotary vane vacuum pump? How to solve it?
1. The pump doesn't work. If the situation is unknown, do not start the pump first, so as to avoid aggravating the fault. You can and can't turn with your hands.
A. The pump can be turned without turning. The causes can be coupling failure, belt slipping, wrong motor wiring, motor damage, power failure, etc.
B. The reason why the pump can't be turned or it is very heavy can be due to the low temperature of the starting pump and the high viscosity of the pump oil; too much return oil due to the design and manufacture of the pump.
Too much return oil caused by too high oil level (too much oil filling, or water vapor condensing in the pump, or the water condensed in the exhaust pipe returns to the pump); there are foreign matters in the pump (welding slag and oxide in the intake pipe; debris of the vane spring and other pump parts); the vane is deformed and stuck; and the occlusion (copper sleeve, rotor, middle wall, pump cover, stator, bearing) occurs.
2. The pump temperature is too high. It refers to the maximum oil temperature measured near the low-level exhaust valve that exceeds the value specified in the instruction manual. Due to the increase of pump temperature, the viscosity of the pump oil will be greatly reduced, and the saturated vapor pressure of the pump oil will be increased, which will increase the limit pressure of the pump and decrease the pumping efficiency; the rubber parts will be easily aged; the thermal expansion will make the operation reliable. The reasons for the pump temperature too high can be that the ambient temperature of the pump is too high, the inlet air temperature is too high, the inlet cooling device fails, the pump operates continuously for a long time, and the inlet pressure is too high; the cooling water of the water cooling pump is insufficient, the design effect of the circulating water is not good, and the temperature control water regulating valve is invalid.
3. Oil leakage. It can occur in shaft seal, sealing surface of oil tank and pump parts, oil drain plug, oil mark, oil hole bulkhead, through-hole connection of stator parts and support, and gas ballast valve (such as 2x-8). It can be caused by seal aging, improper installation, damage and failure, uneven surface, impurities, roughness and casting porosity. If the oil returns after stopping the pump, the oil will enter the gas ballast valve, and oil leakage may occur if the gas ballast valve is not closed.
Self made rubber pad, must use oil resistant rubber, according to the original design shape, the sealing surface is too large when the pressure is not tight, oil leakage.
4. Water leakage. It can occur at water pipe head, water jacket closed cover plane, drain hole plug, drain valve, etc., water jacket drill through, casting defects, frost crack, and may also cause water leakage.
5. The maximum power exceeds the standard. It can be caused by too high inlet pressure, too high exhaust pressure, foreign matters entering into the pump, too high pump temperature, too small clearance between rotating blades, too high voltage, too much pump fluid returning into the pump, etc., which may damage the motor. Long term continuous operation near the maximum power should be avoided as far as possible. If there is sediment on the surface, it should be removed regularly.
6. The limit pressure does not meet the standard. It can be caused by external leakage, internal leakage, oil hole blockage, poor pump oil quality or pollution deterioration, water vapor and other condensable substances, instrument distortion, abnormal pump operation, etc.
When the leakage is more, the 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. The 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 leakage, check the pump outlet, pipeline, valve and container one by one. Failure of the outer shaft seal, oil cup without oil, and air leakage at the end of oil hole can also cause external leakage. The internal leakage can be caused by 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 intake pipe, and the sealing parts of the gas ballast valve, etc., which will increase the operating clearance. When the oil hole is blocked, open the oil filling hole to listen, and the noise of the pump will be lighter. If the hand feels sucked on the exhaust port when the oil tank is well sealed, the exhaust valve may fail.
If the pump oil is clean and has not been used for a long time, the air ballast valve can be opened 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, it can be fully opened to regulate the air volume and purify the operation. If necessary, appropriate amount of gas can be put into the pump port for operation, which can speed up the purification process. If other volatile gases or liquids are pumped in, change the oil in time and wash the oil tank if necessary. Some pumps will deposit pump fluid in the interstage air passage. In order to obtain good oil change effect, it is necessary to try to discharge the deposited pump fluid.
The limit pressure was measured by a seat type compression mercury vacuum gauge. When measured with a calibrated thermocouple vacuum gauge and other full pressure gauges, the measured value will increase. Pay attention to the calibration of thermocouple vacuum gauge. It is recommended to reserve a regulator calibrated at the same time for comparison in case of suspected regulatory contamination distortion.
The increase of the limit pressure will decrease the pumping efficiency and increase the limit total pressure. We can judge, check and deal with the failure of the decrease of the pumping efficiency and the increase of the limit full pressure according to the above introduction.
7. Noise. The noise of the pump will be affected by the structural design of the pump, the noise of the motor and the pump bearing, the smoothness of the moving parts such as the rotating blades, too much oil intake, the noise generated by the fan and the transmission parts, the large air intake volume, the loose parts in the pump such as the air opening and the oil baffle plate, and the vibration caused by the unequal installation will all affect the noise of the pump.
8. Fuel injection. The size, position and sealing condition of the oil return hole of the oil box for preventing oil injection, the design and installation of the oil baffle, the mist eliminator, oil baffle cap and oil-gas separator at the exhaust port, the oil level and the oil inlet volume will affect the fuel injection of the pump. When the pump port is open to the oil atmosphere, the air flow speed at the exhaust port of the direct coupled pump can be as high as 30m / s. when the oil surface is blown open, the circulating oil and gas in the pump will be increased The flow of oil will test the measures to prevent fuel injection.
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