Addtime： 2020-07-18 Browse times： 3741
Common faults of water ring vacuum pump
1、 The vacuum pump is not enough
Possible causes: insufficient motor power supply leads to insufficient speed; insufficient water supply; excessive gap between impeller and distribution plate; leakage and air leakage caused by mechanical seal damage; excessive wear of impeller; and failure to discharge circulating water.
Troubleshooting: check whether the power supply voltage is within the rated voltage range of the motor; increase the water supply (must be controlled in the correct range, otherwise it will lead to overload and heating of the motor); reduce the gap between the impeller and the distribution board (generally 0.15-0.20 mm); replace the mechanical seal; replace the impeller; check the pipeline of the water outlet.
2、 It can't be started or started. It's noisy
Possible causes: the motor power supply voltage is insufficient; the motor is running without phase; the pump has not been used for a long time, resulting in corrosion; impurities are inhaled in the pump; the impeller drags the distribution board.
Troubleshooting: check whether the power supply voltage is too low; check whether the motor wiring is reliable; if the pump has not been used for a long time, rust remover can be added or the pump cover can be opened to remove rust; open the pump cover to remove debris; adjust the distance between impeller and distribution board.
3、 Motor overheating
Possible causes: overload of motor caused by excessive water supply; motor phase loss; exhaust hole blockage; impeller dragging other parts.
Troubleshooting: reduce the water supply to the normal range (refer to the liquid supply in the operation manual of the pump); check whether the wiring is firm; check the exhaust port; open the pump cover to adjust the clearance between the impeller and other parts.
4、 Insufficient flow
Possible causes: leakage of air and liquid in pipeline; increase of resistance loss;
Troubleshooting: check the mechanical seal at the connection; check the pipeline and check valve for faults.
Daily maintenance of water ring vacuum pump:
(1) In normal operation, pay attention to check the operation and lubrication of the bearing. The temperature (bearing and outer circle) is generally 15 ℃～ 20 ℃ higher than the ambient temperature, and the maximum temperature is not allowed to exceed 30 ℃～ 35 ℃, that is, the actual temperature at the outer circle of the bearing frame should not exceed 55 ℃～ 60 ℃; for normal working bearings, oil should be added 3-4 times a year, at least once a year, and all lubricating oil should be cleaned Replace.
(2) In normal operation, the packing should be compressed regularly. If the sealing performance cannot be guaranteed due to wear, the new packing should be replaced. If the mechanical seal is used and the leakage is found, check whether the dynamic and static rings of the mechanical seal have been damaged or whether the auxiliary seal is aging. If the above situation occurs, new parts need to be replaced.
(3) In case of special sound, the pressure plate on both ends of the cover can be removed to check whether the two end faces of the impeller are abraded with the distributor, and whether the exhaust valve plate is normal.
Description of other faults of water ring vacuum pump
Causes of leakage of mechanical seal of 1 vacuum pump
① Improper disassembly of mechanical seal
When replacing the mechanical seal of non energy end, it was found that the O-ring on the moving ring was not installed properly. The O-ring should have been installed outside the sealing groove on the moving ring seat. However, the assembly review found that the O-ring was not equipped with such a device, but was wrongly installed outside the tension spring positioning piece, resulting in the deformation of the tension spring, which completely failed to play the role of axial static sealing, resulting in leakage.
② The pressure of icing water in mechanical seal is too high
The adhesion force of mechanical seal dynamic and static ring is imposed by the tension spring on the moving ring. When the frozen water pressure is too high, the water pressure will act on the dynamic and static rings, because the static rings are vivid and immobile, so the water pressure will stimulate the dynamic rings, compress the tension springs to the same position of the static rings, so as to weaken or eliminate the adhesion force of the static and dynamic ring surfaces, resulting in the leakage of the dense book cover. After the maintenance, the mechanical seal at the energy end is filled with ice water for leakage test. The inlet valve is opened 2 / 3 times, and the mechanical seal is complete without leakage. When the water valve is opened more than 2 / 3, the mechanical seal leaks. The three parties (maintenance party, iron oxide motor branch, Sichuan Dayu mechanical seal making factory) preliminarily concluded that the cause was excessive water pressure. It was suggested that the motor should be started up and put into operation after the repair, so as to further track and find out the real cause of the leakage.
③ The cover of dynamic and static ring is broken
This is an important cause of the leakage of the mechanical seal of the previous replacement of the pump.
The mechanical seals of energy end and non energy end are disassembled on the same shaft, the impeller is installed beside the shaft, and the bearing support at both ends of the shaft is vivid. When replacing the mechanical seal of energy end or non energy end together, the bearing (bearing pedestal) of corresponding end must be assembled first, and the capacity can be stored in the old mechanical seal, and the new mechanical seal shall be installed. At this time, due to the gravity of the shaft and impeller, the impeller and shaft pipe supported by the bearing at one end will be lost and the shaft will be inclined to the non bearing end. Because the static ring at the end of the pump is not removed with bolts on the pump end cover, and the moving ring is wrapped around the shaft together with the shaft. In addition, because the clearance between the inner ring of the static ring and the shaft is very small, when the shaft is collapsed and tilted, it will cause: a. the absolute displacement of the dynamic and static ring at one end, so that the seal cover of the dynamic and static ring is squeezed against each other, resulting in fragmentation; B. the shaft is indirectly pressed on the stationary ring at the unseparated end On the inner ring, the cover of the static ring is broken or broken.
After understanding and synthesizing the previous replacement operations, the reason why the mechanical seal at one end is replaced well and the mechanical seal at the other end leaks is caused by the above components. In fact, our operators have also thought about a problem, but the steps taken are not right: the previous replacement is to use the bamboo shoots to hang the shaft at the disassembly end to prevent the high and low swing of the shaft. In the theoretical operation, it is proved that this hoisting step has great mistakes, especially not applied to this kind of heavy vacuum pump sealing device. The reason is that it is difficult to master the tension of lifting point and bamboo shoot gourd thoroughly, and it is difficult to prevent the high and low swing of stop shaft.
Causes of 2 vacuum pump turning difficulties
① The bearing clearance at both ends of the pump was not adjusted properly.
The bearings at both ends of the pump are double row tapered roller bearings. The inner rings and outer rings of double row tapered roller bearings are in contact with conical surfaces, and the inner rings can be taken in from the outer rings. There is a bearing clearance adjusting spacer ring between the two inner rings, that is, the original clearance of the bearing is controlled by the spacer ring between the two inner rings, and the clearance of the normal bearing has been adjusted before delivery.
The bearing is disassembled on the shaft. One of the two rows of inner rings is on the shoulder of the shaft, and the other row is locked on the shaft by the locking back cap. After locking, the two rows of inner rings and spacer rings need not be tightly connected together. With the shaft rotating together, the outer ring and the bearing box are tightly matched. When the thickness of the gap adjusting spacer ring is less than the original thickness, when the back cap is locked, the inner ring and outer ring of the two rows will be squeezed by force, which makes the bearing difficult or helpless to rotate.
② The bearing inner ring is not installed in place
If the bearing inner ring is not installed in place, the problem mentioned in 1) below will also occur. The reason is that the absolute axial displacement of the inner ring and outer ring causes one of the two rows of inner ring to be pressed against the outer ring. When the energy end bearing was removed, it was found that there was a big eating mark on the shaft surface of the device bearing position. It was concluded that the bearing inner ring was not completely pushed onto the shaft shoulder, which was an important cause of the turning difficulty.
③ The clearance between impeller and pump end face is not adjusted well
The clearance between the impeller and the two end faces of the pump body of the water ring vacuum pump is adjusted by moving the bearing seats at both ends. The adjustment step is to add or subtract gaskets between the bearing pedestal and the support positioning surface of the bearing pedestal.
④ The mechanical seal dynamic and static ring seal book cover is broken and stuck with each other.
Maintenance and routine maintenance of water ring vacuum pump
1. Maintenance of water ring vacuum pump
(1) Pay attention to the oil level and the cleanliness of the oil. Change the oil once every 150 hours after the new pump works, and then change the oil every 2-3 months. If the service conditions are not good, the oil change time can be shortened when the vacuum drops.
(2) Keep the pump and pump room dry and clean.
(3) Always pay attention to the temperature of cooling water and oil, the maximum temperature shall not exceed 85 ℃, the inlet temperature of cooling water shall not exceed 30 ℃, the temperature of outlet water shall not exceed 5 ℃, and the water quality shall be kept clean.
2. Precautions in daily maintenance
(1) Regularly check whether the pipeline and joint of water ring vacuum pump are loose. Turn the water ring vacuum pump by hand to see if the water ring vacuum pump is flexible.
(2) Add the bearing lubricating oil into the bearing body, observe that the oil level should be at the center line of the oil mark, and the lubricating oil should be replaced or supplemented in time.
(3) Screw the water diversion plug of the pump body of the lower ring vacuum pump to inject water (or slurry).
(4) Close the gate valve of water outlet pipeline, outlet pressure gauge and inlet vacuum gauge.
(5) Jog the motor to see if the rotation direction of the motor is correct.
(6) Start the motor. After the water ring vacuum pump operates normally, open the outlet pressure gauge and the inlet water ring vacuum pump. Gradually open the gate valve and check the load of the motor after it shows the appropriate pressure.
(7) The flow and head of the water ring vacuum pump should be controlled within the range indicated on the label as far as possible, so as to ensure that the water ring vacuum pump operates at the highest efficiency point, so as to obtain the maximum energy-saving effect.
(8) During the operation of the water ring vacuum pump, the bearing temperature should not exceed the ambient temperature of 35C, and the maximum temperature should not exceed 80C.
(9) If abnormal sound is found in the water ring vacuum pump, stop the pump immediately to check the cause.
(10) To stop using water ring vacuum pump, close the gate valve and pressure gauge first, and then stop the motor.
(11) In the first month of operation, the lubricating oil of water ring vacuum pump is changed after 100 hours, and then every 500 hours.
(12) The packing gland should be adjusted regularly to ensure that the leakage in the packing chamber is normal.
(13) Regularly check the wear of the shaft sleeve, and replace it in time if the wear is large.
(14) When the water ring vacuum pump is used in cold winter season, it is necessary to screw off the drain plug at the lower part of the pump body to drain the medium. Prevent frost cracking.
(15) The water ring vacuum pump is out of service for a long time. All the pumps should be disassembled, the water should be wiped dry, and the rotating parts and joints should be coated with grease for proper storage.
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