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Vertical multistage centrifugal pump maintenance and disassembly method

20 Jun 2019Email

The vertical multistage centrifugal pump is a vertical multi-stage medium conveying device. The flowing medium (gas and liquid, or a mixture of suspended particles and gas or liquid) enters from the root of the blade shaft (inlet), and the medium depends on high speed rotation. The blades acquire centrifugal force, creating a high pressure that flows out of the pressure relief port (outlet). The vertical multi-stage pump is compact in structure, small in size and beautiful in appearance. Its vertical structure determines the installation footprint is small, and its center of gravity coincides with the center of the pump foot, thus enhancing the running stability and service life of the pump. Here is a description of the disassembly and repair steps of the vertical multistage centrifugal pump:


A. Vertical multistage centrifugal pump disintegration motor:

       1. According to the actual situation of the inspection site (such as: installation of lifting hooks), hanging lifting equipment (hoist, wire rope, drawstring).

       2. Check hooks, rope buckles, hoist locks, and lift the motor to hoist the center of gravity test;

       3. Disassemble the motor power cable, remove the motor and pump body connection screws; remove the motor and water pump coupling connection screws.

       4. Lift the motor. When the motor and the water pump are disconnected for a certain distance, tighten the rope to slowly lower the motor. (Prevent the motor from shifting the center of gravity during the lowering process, damage the equipment and cause injury); Wait for the motor to lay flat Pull out the coupling with the pull code on the wooden board, remove the motor hood, and take out the fan blades.

       5. Check the insulation of the motor winding with a shaker and make a record; then make the removal mark, unscrew the front and rear cover screws of the motor, and take out the end cover.

       6. Check the degree of bearing wear. If you need to replace the bearing, pull out the bearing with the pull code (make the rotor out before taking out the bearing, do not hurt the stator winding when pulling out the rotor, and do some protective measures if necessary).

       7. Replace the motor bearings, methods are: heating method, cooling method, using the cylinder direct pressure method.

       8. If the bearing is going out of the outer ring, check the cooperation of the end cap bearing seat and the bearing. If the bearing is not good, the end cap bearing seat needs to be processed. The assembly motor step is opposite to the motor removal step.

       9. Insulate the motor winding before assembling the motor. (If the motor winding is damp, it must be baked and dehumidified, if necessary, it must be heated and immersed in the insulating paint); the detected value is within the specified range and can be used.


B. Vertical multistage centrifugal pump disintegration pump:

       Because the pump has different manufacturers and different models, the pump structure is also different; however, the pump disassembly and repair steps are slightly different. One is to be removed from the bottom to the next level, and the other is to be removed from the top to the next level. Let's take the (level up) first level level removal as an example:

       1. Close the inlet and outlet valves, drain the water from the pump body, and make the removal mark for each level.

       2. Pull out the coupling on the pump body with the pull code, remove the cover nut, take out the bearing cover, remove the bearing, shaft seal or packing packing. When removing the mechanical seal of the magnetic ring, it is strictly forbidden.

       3. Remove the screw connecting the pump body outlet and the pipe network, and screw out the pump body and base fixing bolts. Tied with 2 twine on the pump body, lift the pump away from the base and slowly lower it. When you put the pump down, remember not to bend the pump shaft and lay the pump on the ground board.

       4. Unscrew the pump shaft nut, remove the bushing, and then remove the impeller. (It is strictly forbidden to directly hit the bushing and impeller by the hammer during the disassembly process.) Finally, remove the casing.

       5. When the bushing, impeller and outer casing of the first stage are removed, the shaft should be removed and the next stage disassembled (the pump shaft below 35mm can not be used as a force tool to move the pump).

       6. The following levels of removal methods are the same as above, please note that the parts removed at each level are placed in order; when the last level of parts are completely removed.

       7. The whole work is transferred to the mating surface between the grinding parts to remove rust and clean scale. Diesel and hazardous substances are strictly prohibited during the cleaning process.


C. Vertical multistage centrifugal pump assembly metering pump body:

       1. When the rust removal, cleaning, and grinding work is completed, start assembling the water pump (the order and method of assembly and disassembly are reversed). First place the level of the bearing on the wooden strip, then place the level of the outlet on top, and then place the shaft with the balance drum in the middle of the level of the inlet and outlet.

       2. Install the first stage impeller on the shaft and place the waterproof ring on the edge of the outer casing.

       3. Install the bushing on the shaft, then install the next-stage outer casing, then install the second-stage impeller, and then install the bushing and the next-stage casing to install the N-stage.

       4. After installing the last stage, tighten the two reverse nuts.

       5. After finishing the above work, hang the pump body on the base and tighten the fixing bolts.

       6. Install the mechanical seal (or install the packing packing), then install the bearing (note the direction of the two bearings) and tighten the nut of the locking bearing.

       7. Manual turning, debugging and rotating is easy, install the coupling.

       8. Place the motor on the chemical pump body and check the spacing between the two couplings, generally 3~5mm. Check the coaxiality between the motor and the pump and tighten the connecting bolts between the motor and the pump body.

       9. Check all the fastening screws of the equipment. Then plug in the motor power cord.

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