Centrifugal pump power machine does not start or power cause and maintenance

Cause of failure 1 The pump speed is too high.

2 The pump shaft is bent and the bearing is worn or damaged.

3 The packing of the pump stuffing box is too tight.

4 The impeller of the pump is stuck by debris or has serious friction with the pump casing.

5 The pump flow rate is too large.

6 The two drive shafts that are driven by the coupling are too tight or the drive belt is too tight.

7 The power of the pump supporting power machine is too low.

8 The pump head is high.

Maintenance method 1 Try to reduce the speed of the pump (take a different diameter of the pulley) or exchange the pump with a lower speed, so that the pump speed and power machine's speed match.

2 after parking. Disassemble the pump body and inspect the pump shaft and bearing. If the pump shaft is bent, the pump shaft should be straightened or replaced.

a. The method of water pump shaft alignment is to take out the water pump shaft and check the bent position. If possible, use a dial gauge on the platform or lathe, or place the pump shaft on the V-shaped iron. The V-shaped iron is first placed firmly, then the dial indicator is supported and the table shaft points to the shaft, and then the pump shaft is slowly pulled. In the case of a curved shaft, the dial gauge has a maximum reading and a minimum for each rotation of the shaft. Reading, the difference between the two readings is the axis of curvature. There are many ways to straighten the pump shaft. The simplest and most convenient method on the spot is to hit the straight shaft method: when the straight shaft is in use, put the shaft on hardwood (or square iron with copper skin). It is required that the support be longer than the boring bar. Soft and has a large contact surface with the crowbar. Face down, hit with a hammer and crowbar. When hitting, start from the place where the bending is largest, and the range of hitting is 1/3 of the circumference, which can be drawn on the shaft in advance. The number of hits in the center of the 1/3 arc is more, and the less the number of hits on both sides, the faster the initial stretch and the slower later. In the process of beating, the change of shaft bending should be measured in time. If the bearing is worn or damaged, the bearing should be repaired or replaced.

b. There are two ways to disassemble a bearing: one is to disassemble it on the shaft; the other is to disassemble it in the end cap.

Use a special puller to pull the bearing out of the shaft; if there is no puller, use a copper bar with a wedge at the end to hold the inner ring of the bearing in an inclined direction, while tapping it with a hoe, while moving the copper rod along the inner ring of the bearing. So that the bearing around the uniform force until the bearing is knocked down; In addition, two thick iron plate can also be used to clamp the bearing under the inner ring of the bearing, and can be supported by a cylinder or bracket that can accommodate the rotating shaft, on the upper end of the shaft Or tap the copper plate to remove the bearing. Because some end cap bearing holes and the bearing outer ring than the bearing inner ring and the shaft with the tighter. Therefore, when removing the end cap, leave the bearing in the end cap bearing hole. When disassembling the bearing, place the end cap facing upwards and place it with a plank of wood around the bearing hole of the end cap, but be careful not to hold the bearing, and then use a copper rod or other metal rod with a diameter slightly less than the outer edge of the bearing. Hold the outer ring of the bearing and use the boring head to knock the bearing out from above.

c. Remove the bearing from the shaft and clean it in cleaning oil (kerosene, diesel, gasoline).

d. First, check the ball, inner and outer raceways for scratches, cracks, or rust spots. Then, the inner ring of the bearing is fixed so that it rotates. If the bearing is normal, it should be rotationally balanced, the rotation speed is uniform, and no noise should be stopped. If the bearing is not normal, the noise, vibration, twisting or sudden stoppage of the rotation will occur. Or when you push the bearing by hand, it will produce a percussive sound or a feeling of excessive play.

e. Bearing failure repair method: According to the cause of the bearing failure and the degree of wear, the exchange method and repair method are often used. The exchange method is used when the wear degree of the bearing does not exceed the allowable value, and when it can continue to be used, the load end (more serious bearing wear) and the non-load end bearing exchange position can be used; the replacement part repair method is when the bearing outer ring or inner If there are cracks, broken balls, broken brackets between the balls, severe discoloration and annealing of the bearing body, deep scratches or rust in the raceways, and bearing wear exceeding the allowable value, new parts should be replaced.

3 After parking, use a spanner to adjust the capping screw of the pump stuffing box, so that the pump shaft can turn freely and the amount of water leakage is moderate (generally, the drop volume is 60 drops/minute).

4 After parking, disassemble the pump body and check the working condition of the impeller. If there is debris on the impeller, the impeller should be removed and the windings should be removed. If the clearance between the impeller and the pump casing is too small, the gap between the impeller and the pump casing should be adjusted to a reasonable value.

5 can be taken to reduce the flow of the water pump to eliminate the method. There are many adjustment methods for the flow rate of the pump water, and the following four are more common: First, the variable flow regulation method adjusts the flow by changing the opening degree of the gate valve on the water pump outlet pipe. The advantage is that it can ensure that the water pump's water output balances with the well's water inflow, and avoids forced downtime due to pumping down the water suction port of the ambassador's pump. The disadvantage is that it will cause the pump to vibrate and shorten the service life of the equipment. Therefore, under normal circumstances, this method should not be used to regulate the flow. The second is the variable speed regulation method, which regulates the flow by reducing (increasing) the speed of the water pump. The change of the speed of the water pump can be realized by replacing the water pump pulley with different diameters or changing the speed of the power machine. Note that the drop of the pump speed should not exceed 30% of the rated speed, and the increase range should be controlled within 10% of the rated speed. This method should be generally preferred. The third is to change the diameter adjustment method, that is to turn the impeller outside diameter appropriately turning smaller, in order to reduce the flow and head of the pump. The fourth is the variable pressure regulation method, which is to reduce the number of stages of the impeller for multi-stage centrifugal pumps, so as to reduce the flow and head of the pump and increase the efficiency of the device, so as to achieve the purpose of economic operation.

6 Check the transmission of the drive shaft and belt after parking. If the coupling is used for transmission, the two axes can be corrected on the same axis by adjusting the installation position of the power machine and the water pump. If belt drive is used, the tension of the belt should be properly adjusted.

a. Coupling installation method Place the steel ruler on the coupling halves of the two halves, then turn the motor shaft by hand and rotate 180° to see if the coupling halves are the same height. If it is inconsistent with the height, it should be corrected. The correct method is to increase or decrease the thickness of the anti-vibration material under the motor frame until it is low and consistent. Explain that the two machines are already in a concentric state, so that the coupling and the motor can be fixed separately, and the mounting bolts and nuts can be tightened.

b. The correction method for the different axes of the transmission shaft indicates that the coupling is installed correctly and the two transmission shafts are coaxial;

7 According to the technical parameters marked on the pump nameplate, reconfigure the power machine to meet the power demand of the pump.

8 For the high lift of the supporting pump, the following methods can be adopted to adjust: First, reduce the speed of the pump properly to reduce the head and eliminate the overload (overload) of the power machine. This method has a larger adjustment, but the speed reduction should be limited to 30% of the rated speed. For belt pumps, this can be achieved by replacing pulleys of different diameters. The second is to turn the pump impeller, or replace the smaller pump impeller to achieve the purpose of reducing the pump lift, but this method has a limited range of adjustment. The third is to replace the low lift pump that matches the power machine.