This time, we will focus on the troubleshooting, daily operation specifications and daily maintenance of various liquid ring vacuum pumps.
liquid ring vacuum pump common faults
1、 Insufficient vacuum
Possible causes: insufficient power supply of motor leads to insufficient speed; insufficient water supply; excessive clearance between impeller and distribution board; mechanical seal damage leads to water leakage and air leakage; impeller wear is too much; circulating water cannot be discharged.
Troubleshooting: check whether the power supply voltage is within the rated voltage range of the motor; increase the water supply (it must be controlled within the correct range, otherwise the motor will be overloaded and heated); reduce the clearance between the impeller and the distribution board (generally 0.15-0.20mm); replace the mechanical seal; replace the impeller; check the pipeline at the water outlet.
2、 The liquid ring vacuum pump can not be started or it is noisy
Possible causes: insufficient power supply voltage of the motor; lack of phase operation of the motor; corrosion of the vacuum pump due to long-time non use; suction of sundries in the pump; impeller drag distribution board.
Troubleshooting: check whether the power supply voltage is too low; check whether the motor wiring is reliable; if the vacuum pump is not used for a long time, add a little rust remover or open the vacuum pump cover to remove the rust manually; open the vacuum pump cover to remove the sundries; adjust the distance between the impeller and the distribution board.
3、 Liquid ring vacuum pump motor overheated
Possible causes: motor overload due to excessive water supply; motor phase loss; exhaust hole blockage; impeller driving other components.
Troubleshooting: reduce the water supply to the normal range (refer to the liquid supply of the vacuum pump operation manual); check whether the wiring is firm; check the exhaust port; open the vacuum pump cover to adjust the clearance between the impeller and other components.
4、 Insufficient flow of liquid ring vacuum pump
Possible causes: pipeline air leakage and liquid leakage; increase of resistance loss;
Troubleshooting: check the mechanical seal at the connection; check the pipeline and check valve for failure.
liquid ring vacuum pump routine maintenance:
(1) In normal operation, pay attention to check the operation and lubrication of the bearing. The temperature (at the bearing and the 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 shall not exceed 55 ℃ ~ 60 ℃; the bearing in normal operation shall be oiled 3 ~ 4 times a year, cleaned at least once a year, and all lubricating oil shall be added Replacement.
(2) In normal operation, the packing shall be pressed regularly. If the packing cannot guarantee the required sealing performance due to wear, the new packing shall be replaced. If the mechanical seal is used and leakage is found, check whether the dynamic and static rings of the mechanical seal are damaged or the auxiliary seal is aging. If the above conditions occur, new parts shall be replaced.
(3) In case of special sound, remove the pressing plate on both ends of the cover, check whether the two ends of the impeller are abraded with the distributor, and check whether the exhaust valve plate is normal.
Description of other faults of liquid ring vacuum pump:
Causes of leakage of mechanical seal of vacuum pump
(1) Improper disassembly of mechanical seal
When replacing the non energy end mechanical seal, it was found that the O-ring on the moving ring was not well installed in the assembly. The O-ring should have been installed outside the sealing groove on the moving ring seat, but the assembly review found that the O-ring was not so equipped, but was wrongly installed outside the tension spring positioning piece, so that the tension spring was deformed, and it could not play the role of axial static seal completely, so as to leak.
(2) Excessive pressure of icing water of machine seal
The binding force of the book cover of the dynamic and static seal ring is imposed by the tension spring on the dynamic ring. When the ice water pressure is too large, the water pressure will act on the dynamic and static rings, because the static ring is vivid and immovable, so the water pressure will activate the dynamic ring, compress the tension spring to the same position of the static ring, so as to weaken or counteract the adhesion force of the static and dynamic rings, resulting in the leakage of the cover. After the maintenance, the machine seal at the energy end shall be connected with ice water for leakage test, and the water inlet valve shall be opened for 2 / 3 times, and the machine seal shall be complete without leakage. When the water valve is opened more than 2 / 3, the machine seal will leak. It is preliminarily determined that it is caused by the excessive water pressure. It is suggested to start the motor for operation after the completion of the motor repair, and further trace and find out the real cause of the leakage.
(3) Dynamic and static book cover broken
This is an important cause of the leakage of the previous replacement of the pump seal.
The energy end and non energy end machine seal are disassembled on the same shaft, the impeller device is beside the shaft, and the bearing support of both ends of the shaft is vivid. When replacing the mechanical seal at the energy end or non energy end together, the bearing (bearing seat) at the corresponding end must be assembled first to store the capacity into the old mechanical seal and install the new mechanical seal. At this time, the weight of the shaft and impeller, the impeller and shaft pipe that lose the support of the bearing at one end, will collapse downward, and the shaft will skew towards the bearing free end. Because the static ring at the end not removed is vividly fixed on the pump end cover with bolts, while the dynamic ring is vividly wound on 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 collapses and skews, it will cause: a. the absolute displacement of the dynamic and static ring at the end not removed, so that the dense book covers of the dynamic and static rings are squeezed with each other, resulting in fragmentation; B. the shaft is indirectly pressed on the static ring at the end not removed On the inner ring, the book cover of the static ring is broken or broken.
After a comprehensive understanding of the previous replacement operations, the reasons for the replacement of one end and the leakage of the mechanical seal at the other end are all caused by the above components. In fact, our operators have also thought about a problem, but the steps taken are not right: the previous several substitutions are to use Cucurbita spp. to hang the shaft at the disassembly end to prevent the high and low swing of the shaft. The theoretical operation proves that there is a big mistake in this lifting step, especially in this kind of heavy vacuum pump mechanical sealing device. The reason is that it is difficult to grasp the tension of the lifting point and the bamboo shoot and melon thoroughly, and it is difficult to prevent the high and low swing of the stop shaft.
The cause of turning trouble of vacuum pump
(1) The clearance between the locating bearings at both ends of the vacuum pump was not adjusted properly.
The bearings at both ends of the vacuum pump adopt double row tapered roller bearings. The two rows of inner rings of double row tapered roller bearings are in contact with the outer ring, and the inner ring can be taken in from the outer ring. There is a bearing clearance adjustment spacer ring between the two inner rings, that is, the original bearing clearance 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 inner rings is on the shoulder of the shaft, the other is locked on the shaft by the locking back cap. After locking, the two inner rings and the spacer ring do not need to be tightly connected to rotate together with the shaft, and the outer ring and the bearing box do not move tightly. When the thickness of the clearance adjusting spacer ring is less than the original thickness, when the back cap is locked, two rows of inner rings and outer rings will be squeezed by incomparable force, which makes the bearing rotation difficult or helpless.
(2) Bearing inner ring not in place
If the inner ring of the bearing is not installed in place, the problem described in 1) below will also occur. The reason is that the absolute axial displacement of the inner and outer rings causes one of the two inner rings to be squeezed by the incomparable force with the outer ring. When removing the bearing at the energy end, it was found that there was a large scratch on the shaft surface of the bearing position of the device. It was concluded that the inner ring of the bearing was not completely pushed on the shaft shoulder, which was an important cause of the turning difficulty.
(3) The clearance between the impeller and the two ends of the vacuum pump is not adjusted properly
The clearance between the impeller of liquid ring vacuum pump and the two end faces of vacuum pump body is adjusted by moving the bearing blocks at both ends. The adjustment procedure is to add and subtract gasket between the bearing seat and the support locating surface of the bearing seat of the device.
(4) Machine seal dynamic and static ring seal book cover is stuck with each other after breaking.