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What is the cavitation margin of the KNOLL centrifugal pump?
2023-09-22 16:39:32
First, the definition of centrifugal pump cavitation allowance:
Acronym for Net positive suction head (ANPA). In practice, this is the parameter that helps us to determine that the pump is operating correctly without going into cavitation.
Therefore, the best way to understand whether and to what extent this phenomenon, which is so detrimental to the service life of the machine, will occur is to compare the available NPSH parameters with the required NPSH.
The first is the minimum NPSH value required for the pump to avoid cavitation. This parameter varies by device model, so it must be checked in the technical documentation provided by the manufacturer with each project.
Another aspect to consider is the available cavitation margin, which depends on the characteristics of the loop and also indicates the risk of cavitation. It varies according to the pressure drop in the suction circuit, the vapor pressure of the liquid, and the suction pressure head.
Cavitation is a phenomenon that occurs when the pressure in a pipe drops below the vapor pressure. At that moment, bubbles form, condensing as the liquid fluid moves through the pipe to a place of greater pressure, causing negative instability to the elements that share the pipe.
If this phenomenon occurs, the material of the pump will be weakened, resulting in rust, vibration, noise, and even pitting, thereby shortening the service life of the centrifugal pump.
Different degrees of cavitation can be detected: moderate cavitation, which allows fluid to flow but with less flow than usual, more or less greatly reduces the performance of the centrifugal pump. In addition, there are serious cavitation conditions that completely affect the pumping capacity of the machine.
Second, how to avoid cavitation of centrifugal pump?
To avoid these problems, a safety ratio of 0.5 m must be observed:
NPSHdisp (NPSHavailable) ≥ NPSHreq (NSPH required) + 0.5
In this equation, it must be taken into account that the NPSHreq value is set only by the factory characteristics of the pump. It is always positive and varies according to engine speed and flow.
This value shows the pumping capacity of the pump at a given point in its operation. In fact, we can say that the lower the NPSHreq value, the higher the suction capacity of the pump.
However, depending on the type of installation, the NPSHdisp is equivalent to the pressure reserve of the fluid vapor pressure, which you must calculate.
NPSHdisp can be calculated using two formulas that analyze parameters such as suction, fluid density, pressure level, gravity, and vapor.
What does the above sayisKNOLLKono centrifugal pumpThe cavitation allowance problem. In addition, Shenzhen Oudejie Technology specializes in selling new imported KNOLL centrifugal pumps, and promises to sell products are new imported products, while providing our customers with quotation, selection, product information and other services.
