Everyone, I’m reviewing **Principles of Chemical Engineering** again, and there’s a question I can’t understand. Please give me some guidance
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The sentence marked with a red line in the image states that, in order to prevent the water in the pipeline from vaporizing, the \"static pressure\" at the cross-section of the pipeline in this area should be slightly greater than the saturated vapor pressure of water at the operating temperature. In the section on the cavitation resistance of centrifugal pumps in Chapter 2 of Tianjin University’s version of Chemical Engineering Principles, it is stated that in order to prevent cavitation from occurring, the sum of the \"static head\" and \"dynamic head\" of the liquid at the inlet of the centrifugal pump must be greater than the saturated vapor pressure head of the liquid at the operating temperature. Which one should be taken as the standard in calculations?
If calculated based on the principle that static pressure is greater than the saturated vapor pressure, it should be P/ρ = PV/ρ； If calculated based on the static head and dynamic head as well as the saturated vapor pressure, it should be P/ρ + u²/2 = PV/ρ. The calculation results must be different, right?
Cavitation does not occur indeed when the sum of the static head and the dynamic head is greater than the saturated vapor pressure head of the liquid at the operating temperature. According to the problem statement, at D’s highest height, the velocity can be approximated as zero; only the static pressure head needs to be considered