What is the reason that the centrifugal pump can not meet the requirements of flow and lift?
1. Air leakage of centrifugal pump or suction pipe;
2. The suction pipeline or centrifugal pump inlet is blocked, and the suction resistance is too large;
3. The wear clearance of impeller ring is too large;
4. The impeller is blocked or severely worn and corroded;
5. The rotation direction of the centrifugal pump is not right or the impeller is installed reversely;
6. The outlet valve of centrifugal pump is not opened or not opened enough;
7. The motor speed is not enough;
8. The type selection or performance of centrifugal pump is inconsistent.
Treatment method:
1. Check and clean the suction valve and pipeline;
2. Remove the blockage or replace the impeller;
3. Replace the impeller seal ring;
4. Check and eliminate air leakage;
5. Open the outlet valve of the pump and adjust the valve opening;
6. Adjust the rotation direction of the pump;
7. Increase the motor speed;
8. Check whether the performance parameters of the pump meet the requirements of working conditions, and adjust them.
How to improve the head and flow of centrifugal pump?
Because the relationship between centrifugal pumps is difficult to express by theoretical formula, it is generally determined by experiment. It includes H-Q curve, n-q curve and efficiency-q curve. The characteristic curve of centrifugal pump is generally provided by the manufacturer of centrifugal pump and plotted in the sample or product manual of the pump. The determination condition is generally 20 ℃ clear water and the speed is fixed. With the increase of flow rate, the pressure head of the pump decreases, that is, the larger the flow rate is, the smaller the mechanical energy provided by the centrifugal pump to the unit weight fluid is. However, this rule may not be applicable to the case of small flow.
The shaft power increases with the increase of the flow rate, and the shaft power is the minimum when the flow rate is zero, so the large flow rate transmission must correspond to the large matching motor. In addition, this law also suggests that the centrifugal pump should be started when the outlet valve is closed, so that the starting current of the motor can be minimized to protect the motor.
The efficiency of centrifugal pump increases with the increase of flow rate, and decreases after reaching a maximum value. But when the flow is zero, the efficiency is zero. When selecting the pump according to the production task, the pump should work near the maximum rate point, and the efficiency within its range is generally not less than 92% of the maximum rate point.
Specific methods: increase the speed, change the impeller width or pipeline.
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