Detailed Explanation Repair And Maintenance Of Multistage Centrifugal Pump
The multi-stage pump is a centrifugal pump that is combined with the inlet and outlet sections and the middle section by a tie rod. Its output water pressure can be very large, and it also relies on the rotation of the impeller to obtain the centrifugal force and thus the material.
When the gas density reaches the working range of the mechanical vacuum pump, it is pumped out, thereby gradually obtaining a high vacuum.
The multi-stage pump relies on the change of the volume of the pump cavity to achieve suction, compression and exhaust, so it is a variable-volume centrifugal pump.
Structure description:
The basic structure of the multi-stage pump is composed of the inlet section, outlet section, middle section, tail cover, impeller, pump body, pump shaft, bearing, sealing ring, stuffing box and other components.
1. The impeller is the core part of the multi-stage pump. It has a high speed and a large output. The blades on the impeller play a major role. The impeller must pass the static balance experiment before assembly.
The inner and outer surfaces of the impeller are required to be smooth to reduce the frictional loss of water flow.
2. The inlet section, outlet section and middle section are also called pump casings, which are the main body of the multi-stage pump.
It plays the role of supporting and fixing, and is connected with the bracket where the bearing is installed.
3. The function of the pump shaft is to connect the motor with the coupling and transmit the torque of the motor to the impeller, so it is the main component to transmit mechanical energy.
4. The bearing is a member that is sleeved on the pump shaft to support the pump shaft. There are two types of rolling bearings and sliding bearings. Rolling bearings use butter as a lubricant. It is appropriate to refuel. Generally, 2/3 ~ 3/4 of the volume will generate heat, too little and there will be noise and heat! The sliding bearing uses transparent oil as the lubricant, add oil to the oil level line.
Too much oil should seep along the pump shaft and drift, and too little bearing should be overheated and burned out to cause an accident
During the operation of the pump, the temperature of the bearing is up to 85 degrees, and generally runs at about 60 degrees. If it is high, it is necessary to find the cause (whether there are impurities, whether the oil is black, and whether it is water) and handle it in time!
5. Sealing ring is also called leakage reduction ring.
If the gap between the impeller inlet and the pump casing is too large, the water in the high-pressure area of the pump will flow to the low-pressure area through this gap, affecting the output of the pump and reducing efficiency.
If the clearance is too small, it will cause friction between the impeller and the pump casing and cause wear.
In order to increase the backflow resistance, reduce the internal leakage, and delay the service life of the impeller and the pump casing, a sealing ring is installed at the joint of the pump casing inner edge and the impeller external assistance, and the sealing gap is preferably maintained between 0.25 ~ 1.10mm.
6. The stuffing box is mainly composed of packing, water sealing ring, packing cylinder, packing gland, and water sealing tube.
The purpose of the stuffing box is mainly to close the gap between the pump casing and the pump shaft, so that the water flow in the pump does not flow to the outside and the outside air does not enter the pump.
Keep the vacuum in the pump always. When the friction between the pump shaft and the packing generates heat, it is necessary to rely on the water seal tube to hold the water into the water seal ring to cool the filler and keep the pump running normally. Therefore, special attention should be paid to the inspection of the stuffing box during the running inspection of the pump! The packing should be replaced after about 600 hours of operation.
7. The import and export can be changed. Multi-stage pump
Features
Multi-stage pump refers to a pump with two or more impellers.
Maintenance
1. Check the multi-stage pump piping and joints for looseness. Turn the multi-stage pump by hand to see if it is flexible.
2. Add bearing lubricating engine oil to the bearing body, observe the oil level should be at the centerline of the oil standard, and the lubricant should be replaced or supplemented in time.
3. Unscrew the water diversion plug of the pump body of the multi-stage pump and pour the water diversion (or slurry).
4. Close the gate valve, outlet pressure gauge and inlet vacuum gauge of the outlet pipe.
5. Jog the motor to see if the motor turns correctly.
6. The multi-stage pump will be discontinued for a long time. It is necessary to disassemble the pump completely, wipe off the water, and apply grease to the rotating parts and joints.
7. Try to control the flow and head of the multi-stage pump within the range indicated on the label to ensure that the multi-stage pump operates at the highest efficiency point to obtain the maximum energy saving effect.
8. During the operation of the multi-stage pump, the bearing temperature cannot exceed the ambient temperature of 35C, and the maximum temperature must not exceed 80C.
9. If abnormal sound of multi-stage pump is found, stop immediately and check the cause.
10. When the multi-stage pump is to be stopped, first close the gate valve and pressure gauge, then stop the motor.
11. In the first month of operation, the multi-stage pump replaces the lubricant after 100 hours, and then changes the oil once every 500 hours thereafter.
12. The multi-stage pump often adjusts the packing gland to ensure that the drip leakage in the packing chamber is normal (it is better to let the drip leak out).
13. Regularly check the wear of the multi-stage pump sleeve, and replace it in time after the wear is large.
14. When the multi-stage pump is used in the cold winter season, after stopping, the water drain plug at the lower part of the pump body needs to be unscrewed to release the medium. Prevent frost cracking.
15. Start the motor. After the multi-stage pump runs normally, open the outlet pressure gauge and the inlet vacuum pump to see that it shows the appropriate pressure, and then gradually open the gate valve, and at the same time check the motor load.
