Principle, structure, operation and maintenance of rotary vane vacuum pump


Use of rotary vane vacuum pump

  • 1. Before use, the product manual for journalists should be carefully checked, and the shipping quality should be checked after unpacking. Collect the spare parts and technical documents, and remove the exhaust protection parts. Install, wire, and try steering as required. The water cooling pump receives water. …
  • 2. In order to prevent fuel injection due to oil return and reversal, the pump port should be opened first, and the internal oil of the pump should be turned into the fuel tank by hand according to the specified steering. At the same time, check the oil level. It should be above the center of the oil mark, but not full. …
  • 3. Auxiliary method for judging steering. Put the sheath upside down on the pump port, if it is sucked after the pump is turned on, it is forward, blown off, it is reverse. Normal sound is forward, abnormal sound is reverse. …
  • 4. If an inflatable solenoid valve is installed at the pump port, it should generally be installed horizontally and act simultaneously with the pump. …
  • 5. When the relative humidity is high or the condensable steam such as water vapor in the pumped gas, gas ballast valve should be used. …
  • 6. According to the instruction manual, select the vacuum pump oil. Note that ester vacuum pump oil cannot be mixed with mineral oil vacuum pump oil and other oils. It must be strictly cleaned before changing into ester vacuum pump oil. …
  • 7. Check the ultimate pressure of the pump with a compression vacuum gauge. The full pressure gauge should pay attention to the pairing calibration of the gauge and the gauge and the backup comparison gauge. It is recommended to install a ball valve between the gauge and the pump under test. If the valve is closed in case of any test, the time of use of the regulation can be extended. …

2. Maintenance of rotary vane vacuum pump

  • 1. First of all, we must understand the type, characteristics and current situation of the pump. Understand the requirements for use and determine the repair target. Before carrying out repairs, prepare inspection methods. …
  • 2. Judge the fault and diagnose the fault. Judgment is accurate and saves trouble. The diagnosis needs to be verified. …
  • 3. To troubleshoot, simplify first and then complicated, easy first and difficult later. Do not dismantle those that do not need to be dismantled. In order to reduce new damage caused by lack of special tools and improper operation, reduce position changes and running-in running time. Generally speaking, the spliced ​​rotor is not removable, otherwise the shape and position tolerance will not be guaranteed and the rotor will be scrapped. …
  • 4. Toxic, harmful and corrosive pumps, users should be asked to clean them first, and the necessary protective measures should be informed to protect the health of maintenance personnel. …
  • 5. Fault classification: It is recommended to divide the faults into operation faults and performance faults. Operational failures may include pump not running, pump temperature is too high, oil leakage, water leakage, maximum power exceeding standard, etc. Performance failures may include limit pressure, limit full pressure, pumping efficiency, noise, fuel injection, gas ballast performance and other substandard or failure to meet requirements. …

3. Examples of fault judgment and diagnosis

1. The pump does not rotate. If the situation is unknown, do not start the pump first to avoid aggravating the fault. Can and cannot be rotated by hand. …

  • A. The pump can rotate without turning. The reason can be coupling failure; belt slippage; motor wiring error; motor damage; power failure, etc. …
  • B. The reason can be that the starting pump temperature is too low and the viscosity of the pump oil is too high; the pump stops and returns too much oil due to design and manufacturing reasons. Too high oil level caused the pump to stop and return too much oil (too much oil, or water vapor condensed in the pump, or water condensed in the exhaust pipe flows back to the pump); foreign matter in the pump (welding in the intake pipe) Slag, oxide; debris from pump parts such as rotary leaf springs); rotary leaf deformation and jamming; seizure occurred (copper sleeve, rotor, middle wall, pump cover, stator, bearing). …

2. The pump temperature is too high.

Means that the highest oil temperature measured near the low-level exhaust valve exceeds the value specified in the instruction manual. As the temperature of the pump rises, the viscosity of the pump oil will drop drastically, and the saturated vapor pressure of the right-to-use pump oil will rise, which will increase the ultimate pressure of the pump and decrease the pumping efficiency; make the rubber parts easy to age; thermal expansion makes the operation reliable . The reason for the high pump temperature can be that the ambient temperature of the pump is too high, the intake air temperature is too high, the intake air cooling device fails, and the pump enters the medium pressure for long-term continuous operation; the cooling water volume of the water-cooled pump is insufficient, and the circulating water design effect is not good; Failure of the water control valve, etc. …

3. Oil leakage.

It can occur in the shaft seal, the sealing surface of the fuel tank and pump parts, the oil drain plug, the oil mark, the oil hole bulkhead, the through hole connection between the stator part and the support, and the gas ballast valve (such as 2X-8). It can be caused by aging of the seal, 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 ballast valve, and oil may leak if the gas ballast valve is not closed. When making your own rubber pads, you must use oil-resistant rubber and follow the original design shape. If the sealing surface is too large, it will leak if it is not tightly pressed. …

4. Water leakage.

It can happen at the head of the water pipe, the flat surface of the water jacket, the screw plug of the drain hole, the drain valve, etc., the water jacket is drilled through, the casting defect, the freezing crack, and it may also cause water leakage. …

5. The maximum power exceeds the standard.

It can be caused by the long-term continuous working inlet pressure is too high, exhaust pressure is too high, debris enters and seizures, pump temperature is too high, rotary vane and other matching gaps are too small, voltage is too high, pump fluid returns to the pump too much, etc. Damage the motor. Try to avoid long-term continuous operation near the maximum power. If there are deposits on the surface, they must be removed regularly. …

6. The ultimate pressure is not above the standard.

It can be caused by external leakage, internal leakage, oil hole blockage, poor pump oil quality or pollution deterioration, moisture and other condensable substances, instrument distortion, abnormal pump operation, etc. …

When there is a lot of leakage, white steam can be seen at the exhaust port. There are many bubbles at the oil mark, and you feel the exhaust pressure on the exhaust port with your hand. There are more bubbles on the oil surface of the low-level exhaust valve. The power will increase. At this time, first check whether the gas ballast valve has been closed. Since each new pump is shipped from the factory, the ultimate pressure is measured at the pump port, so if there is any leakage, the pump port, pipes, valves, and containers should be checked one by one. Outer shaft seal failure, no oil in the oil cup, and air leakage in the oil hole can also cause external leakage. Internal leakage can be caused by wear, corrosion, and seizure 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, the gas ballast valve seal, etc., which will increase the operating clearance. Big. When the oil hole is blocked, open the fuel hole and listen, the noise of the pump will be lighter. In the case of a good tank seal, if the hand feels sucked on the exhaust port, the exhaust valve may fail. If the pump oil is clean and has not been used for long-term storage, the gas ballast valve can be opened to purify the water vapor in the pump. If it is invalid, check the meter. If the pump oil is yellow, white and emulsified, the gas ballast can be fully turned on, and the air ballast capacity can be adjusted for purification operation. If necessary, an appropriate amount of gas can be put into the pump port to operate, which can speed up the purification process. If other volatile gases or liquids are pumped in, the oil should be changed in time, and the oil tank should be washed if necessary. Some pumps will deposit pump fluid in the interstage airway. In order to achieve a good oil change effect, try to drain the deposit pump fluid. The ultimate pressure is measured with a seat-type compression vacuum gauge. When measuring with a full pressure gauge such as a calibrated thermocouple vacuum gauge, the measured value will increase. Note that the gauges of thermocouple vacuum gauges must be paired and calibrated. It is recommended to reserve a gauge that is calibrated at the same time for comparison when the gauge is suspected of contamination and distortion. An increase in the ultimate pressure will decrease the pumping efficiency during the high vacuum period, and will also increase the ultimate full pressure. You can refer to the above introduction to judge, check, and deal with the failure of the pumping efficiency drop and the limit full pressure increase. …

7. Noise.

The structure design of the pump, the noise of the motor and the pump bearing, whether the moving parts such as the rotary vane are smooth, the oil intake is too much, the noise generated by the fan and the transmission parts, the air intake is large, the gas ballast operation, the oil baffle, etc. Loose internal parts and vibration caused by unequal installation will affect the noise of the pump. …

8. Fuel injection.

The size, position and sealing condition of the oil return hole of the oil box used to prevent fuel injection, the design and installation of the oil baffle plate, the mist reducer, the oil baffle cap, the oil and gas separator of the exhaust port, the height of the oil level, and the oil intake The volume of the pump will affect the fuel injection of the pump. When the pump port is open to the oil atmosphere, the airflow speed of the direct-connected pump exhaust port can be as high as 30M/S. When the oil surface is blown, the circulating oil in the pump and the oil carried by the airflow Various measures to prevent fuel injection will be tested. …

Others.

Some pumps have oil pumps, oil separators, one-way valves on the oil circuit, mist eliminators, inlet filters (for preventing oil vapor recirculation), inlet dust filters and other components or accessories. Also check. The failure of the oil pump will cause the lubrication and sealing of the pump to fail. The failure of the mist eliminator may increase the exhaust pressure, increase the power, and damage the motor. The failure of the inlet filter can increase the air intake resistance, reduce the pumping speed, and reduce the pumping efficiency. decline. …

Cleaning.

It is not suitable to soak, lest the lotion enters the splicing rotor and is difficult to discharge. …

Disassembly and assembly.

It should be carried out in an orderly manner in accordance with the recommendations and regulations of the instruction manual, remember the position and place it reasonably to avoid wrong installation.

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