Maintenance method of the hottest two-stage rotary

Maintenance methods of two-stage rotary vane vacuum pump

1. First of all, we should understand the type, characteristics and current situation of the pump. Understand the use requirements and determine the repair objectives. Prepare the inspection means before maintenance

2. Judge the fault and confirm the fault. Accurate judgment saves trouble. The diagnosis should be verified

3. Troubleshooting should be simple before complicated, easy before difficult. Do not disassemble those that do not need to be disassembled. In order to reduce the new damage caused by the lack of special tools and improper operation, and reduce the position change and running in operation time. Generally speaking, the spliced rotor is not removable, otherwise the geometric tolerance will not be guaranteed, and the rotor will be scrapped

4. For toxic, harmful and corrosive pumps, please ask the user to clean them first and inform the necessary protective measures to ensure the health of maintenance personnel

5. Fault classification

it is recommended to divide faults into operation faults and performance faults

operation faults may include non rotation of the pump, too high pump temperature, oil leakage, water leakage, excessive maximum power, etc

performance failures can include extreme pressure, extreme full pressure, extraction efficiency, noise, fuel injection, gas ballast performance. It is said that the lightweight solutions provided to meet these challenges are not up to standard or can not meet the requirements

6. Examples of fault judgment and diagnosis

(1) the pump does not turn. If the condition is unknown, do not start the pump first to avoid aggravating the fault. It can and cannot be turned by hand

① the pump can be turned without rotation. The reason can be the coupling failure; Belt slipping; Wrong wiring of motor; Motor damage; Power failure, etc

② if it cannot be turned or it is very heavy, the reason may be that the starting pump temperature is too low and the pump oil viscosity is too high; There is too much oil return after pump shutdown due to design and manufacturing reasons. Too much oil is returned when the pump is stopped due to too high oil level (too much oil is added, or water vapor condenses in the pump, or water condensed in the exhaust pipe returns to the pump); There are foreign matters in the pump (welding slag and oxide in the air inlet pipe; debris of pump parts such as rotary leaf spring; the rotary leaf is deformed and stuck; occlusion occurs (copper sleeve, rotor, middle wall, pump cover, stator, bearing)

(2) the pump temperature is too high. It refers to the maximum oil temperature measured near the low-level exhaust valve, which converts the problem of measuring the load into the problem of measuring the displacement of the rod assembly. 10. The lower fixture adopts ball screw and FM electromechanical drive, which exceeds the value specified in the instruction manual. As the pump temperature increases, the viscosity of the pump oil will decrease significantly, and the saturated vapor pressure of the pump oil will increase, so that the limit pressure of the pump will increase and the pumping efficiency will decrease; Make rubber parts easy to aging; Thermal expansion reduces the running clearance, especially the thickness direction of some non-metallic rotary blades and the clearance of the inner hole of the copper sleeve, which affects the reliability of pump operation. The reason why the pump temperature is too high 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 inlet pressure of the pump is too high for long-term continuous operation; The cooling water volume of water cooling pump is insufficient, and the design effect of circulating water is poor; Failure of temperature control water volume regulating valve, etc

(3) oil leakage. It can occur at the shaft seal, the sealing surface of oil tank and pump parts, oil drain plug, oil pointer, oil hole bulkhead, the through-hole connection between stator components 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 stopping the pump, the oil will enter the gas ballast valve, and oil leakage may occur if the gas ballast valve is not closed. When making self-made rubber pads, you must use oil-resistant rubber according to the original design shape. If the sealing surface is too large, it will leak oil if it is not pressed tightly

(4) water leakage can occur at the water pipe joint, the water jacket blind cover plane, the drain hole plug, the drain valve, etc. water jacket drilling through, casting defects, freezing cracks, may also lead to water leakage

(5) high power exceeds the standard. It can be caused by long-term continuous operation, too high inlet pressure, too high exhaust pressure, occlusion of sundries, too high pump temperature, too small matching clearance of rotating blades, too high voltage, too much pump fluid returning into the pump, etc., which will damage the motor. Try to avoid long-term continuous operation near the maximum power. If there is sediment on the surface, it should be removed regularly

(6) the limit pressure is not up to standard

can be caused by external leakage, internal leakage, oil hole blockage, poor pump oil quality or pollution deterioration, condensable substances such as water vapor, instrument distortion, abnormal pump operation, etc

when there are many external leaks, white steam can be seen at the exhaust port. There are many bubbles at the oil mark, and the hand can feel 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 air ballast valve has been closed. Since the limit pressure of each new pump is measured at the pump outlet, if there is external leakage, the pump outlet, pipes, valves and containers should be checked one by one. Failure of the outer shaft seal, no oil in the oil cup, and air leakage in the oil hole bulkhead can also cause external leakage. Internal leakage can be caused by the moving clearance in the pump, the plane of the exhaust valve seat, the sealing surface of the exhaust valve, the inner shaft seal, the plane of the pump cover, the intake pipe, the air ballast valve seal, etc. Wear, corrosion and occlusion will increase the running clearance. When the oil hole is blocked, open the oil filling hole and listen. The noise of the pump will be light. When the oil tank is well sealed, if your hand feels sucked on the exhaust port, the exhaust valve may fail

if the pump oil is clean and unused for a long time, open the gas ballast valve to purify the water vapor in the pump. If it is invalid, check the instrument. If the pump oil turns yellow and white and has been emulsified, the gas ballast can be fully turned on, and the atmospheric ballast purification operation can be adjusted. If necessary, an appropriate amount of gas can be put into the pump port for operation to speed up the purification process. If other volatile gases or liquids are pumped, change the oil in time, and wash the oil tank if necessary. Some pumps will deposit pump fluid in the interstage airway. In order to achieve good oil change effect, try to discharge the deposited pump fluid

the limit pressure is measured with a seat compression mercury vacuum gauge

when measured with a calibrated thermocouple vacuum gauge or other full pressure gauge, the measured value will increase. Note that the regulation of thermocouple vacuum gauge should be paired and calibrated. It is recommended to reserve a gauge calibrated at the same time for comparison in case of suspected pollution distortion

the increase of limit pressure will reduce the pumping efficiency in high vacuum period, and also increase the limit full pressure. Refer to the above introduction to judge, check and deal with the faults of decreasing extraction efficiency and increasing ultimate full pressure

(7) noise. The structural design of the pump, the noise of the motor and pump bearings, whether the moving parts such as rotating blades are smooth, the oil inlet is too much, the noise and air inlet produced by the fan and transmission parts are large, the air opening ballast operates, the oil baffle and other parts in the pump are loose, and the installation inequality causes vibration, which 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 oil injection, the design and installation of the oil baffle, the mist eliminator, oil baffle cap and gas separator at the exhaust port, the level of the oil level and the size of the oil inlet will affect the oil injection of the pump. When the pump door is open to pump the atmosphere, the air velocity at the exhaust port of the direct coupled pump can be as high as 30m/s, and the technical index of the oil level projector is: H, The circulating oil in the pump and the oil brought out by the air flow will test various measures to prevent fuel injection

7. Others. Some pumps have oil pumps, oil separators, check valves on the oil circuit, mist eliminators, inlet filters (for preventing oil vapor backflow), inlet dust filters and other components or accessories, which should also be checked. The failure of the oil pump will make the lubrication and sealing of the pump invalid, and 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 intake resistance, reduce the pumping speed, and reduce the pumping efficiency

8. Cleaning. It is not suitable for soaking. It is difficult to discharge the washing free liquid when it enters the splicing and turns inside

9. Disassembly and assembly. It should be carried out in an orderly manner in accordance with the recommendations and regulations of the book, remember the location and place it reasonably to avoid wrong loading