What are the reasons for the drop in outlet pressure of stainless steel vertical multistage centrifugal pumps
Knowing the cause of the drop in the outlet pressure of the stainless steel vertical multistage centrifugal pump, the failure of the vertical multistage centrifugal pump can be resolved as long as specific measures are taken for the specific situation. The reasons are as follows:
(1) Motor reversal of stainless steel vertical multistage centrifugal pump
Due to the wiring, the steering of the motor will be opposite to the actual steering of the pump. In this way, the steering of the pump should be observed before starting. If the steering is reversed, any two wires on the terminal of the motor should be exchanged.
(2) Internal leakage of stainless steel vertical multistage centrifugal pump
When the gap between the rotating part and the static part in the pump exceeds the design range, it will cause internal leakage, which is reflected in the discharge pressure of the pump, such as the impeller ring gap, the interstage gap of the multi-stage pump. At this time, the corresponding disassembly and inspection should be carried out to repair or replace the parts that cause the gap to be too large
(3) The speed of the stainless steel vertical multistage centrifugal pump is reduced
The important factors that affect the pump head are the outer diameter of the impeller and the speed of the pump. Under other conditions unchanged, the pump head is proportional to the square of the speed. It can be seen that the speed has a great influence on the head, sometimes because of Some external reason causes the pump speed to decrease, which will reduce the pump head accordingly. At this time, the speed of the pump should be checked. If the speed is indeed insufficient, the reason should be checked and reasonably resolved.
(4) Cavitation at the inlet of the stainless steel vertical multistage centrifugal pump
If the suction pressure of the pump is too low, below the saturated vapor pressure of the pumped medium, cavitation will occur. At this time, check whether the inlet piping system is blocked or whether the opening of the inlet valve is too small, or increase the liquid level of the suction tank.
(5) The working point of the stainless steel vertical multistage centrifugal pump is shifted to large flow and low head
In general, vertical multistage centrifugal pumps have a continuous downward performance curve, and the flow rate gradually increases as the head decreases. During the operation process, due to some reason, the back pressure of the pump is reduced, and the working point of the pump passively shifts to the low-lift and large-flow point with the curve of the device, which will cause the reduction of the head. Caused by the change, there is no special relationship with the pump itself. At this time, as long as the pump back pressure is increased, such as closing a little outlet valve, the problem can be solved.
(6) The impeller flow channel of stainless steel vertical multistage centrifugal pump is blocked
If the impeller part of the flow channel is blocked, it will affect the work of the impeller, resulting in a drop in outlet pressure. Therefore, it is necessary to disassemble the pump and check to remove foreign objects. In order to prevent this problem from happening again, a filtering device can be added before the pump inlet if necessary.
