What is the difference between the necessary cavitation allowance of the pump and the effective cavitation allowance and the effective cavitation allowance

For a given pump, the cavitation allowance required at a given speed and flow rate is called the necessary cavitation allowance of the pump, which is commonly used in NPSH. Also called NPSH, is provided to achieve.NPSH pump cavitation performance parameters, the internal flow and the centrifugal pump is composed of pump head itself, its physical meaning is expressed in part of the pump inlet pressure drops of liquid level, which is in order to guarantee the pump cavitation does not occur, with surplus energy more than vaporization pressure head in the inlet of the pump unit weight of liquid. The cavitation allowance of stainless steel self priming pump has nothing to do with the device parameters. It is only related to the motion parameters of the pump inlet part (uo, wo, wk&rdquo, etc.). These motion parameters are determined by geometric parameters under certain speed and flow rate. That is to say z PSH. It is determined by the pump itself (the geometric parameters of the suction chamber and the inlet part of the impeller). For a given pump, no matter what medium (viscous medium is due to velocity distribution), at a certain speed and flow rate, the same pressure drop is observed at the pump inlet, which is the same as that of NPSH. because of the same speed. So NPSH is independent of the properties of the liquid (not considering the thermodynamic factors). The smaller the NPSH, the lower the pressure drop, which requires the device to provide the NPSH. As a result, the better the anti cavitation performance of the pump is. Effective cavitation allowance refers to the cavitation allowance determined by the installation conditions of the pump, which is commonly used as NPSH. It is also known as the device's cavitation allowance, which is a surplus energy supplied by the suction unit for the unit weight liquid at the inlet of the pump over the vaporized head. NPSH. The bigger the pump, the more it is not easy to have a cavitation. The size of effective cavitation and the parameters of the device and the properties of the liquid (p.P. And so on. Because the hydraulic loss of the suction device is proportional to the square of the flow, the NPSH. decreases with the increase of the flow. What is the difference between cavitation allowance

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