The relationship between pump cavitation and the inlet pipeline
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Does pump cavitation have anything to do with the nominal diameter of the inlet pipeline? Our company has a self-priming centrifugal pump with a power rating of 75 KW, a head of 70 M, and a rated flow rate of approximately 180 cubic meters per hour. The inlet flange is DN125, while the outlet is DN80. When installing the piping, DN150 pipes are used to connect to the inlet flange via eccentric reducers; the distance from the suction inlet to the center of the pump’s inlet flange is about 4.6 meters, and the horizontal section at the inlet is approximately 2.8 meters long. A filter and a gate valve are installed at the inlet. When in use, the machine generates knocking noises in its self-priming chamber, and these noises are quite loud from the outside. A vibration meter showed that the radial vibration of the pump bearings was 7 mm/s, while the radial vibration of other components was 4–6 mm/s. Based on the pump parameters, cavitation is not expected to occur, and there are no issues such as flow resistance or poor exhaust during operation. I wonder if cavitation can occur under such operating conditions? Is there any way to improve its operating conditions?
It is estimated that the effective net positive suction head is too low; calculate it and compare it with the pump’s allowable net positive suction head. https://bbs.hcbbs.com/thread-1764877-1-1.html
Is the inlet pipe a bit longer? The distance from the suction inlet to the center of the pump inlet flange is approximately 4.6 meters, the horizontal section at the inlet is about 2.8 meters, and the inlet is equipped with a filter and a gate valve. High inhalation resistance can cause cavitation
The net positive suction head is 3.8 meters; I’m not sure if that’s sufficient
The suction lift is about 6 meters, no problem. If cavitation is suspected, the liquid level can be increased appropriately, the filter screen should be checked, the gate valve must be fully open, and the medium temperature as well as the integrity of the pipes should be verified.
It is recommended to connect a vacuum gauge at the inlet flange to monitor the pressure level, so as to determine whether cavitation is occurring in the pump
The flow velocity at the inlet is quite high; cavitation must be occurring
There is another question: was there an overload of traffic during operation?
Has the original poster resolved their issue? ? Could you share it? Thank you