I would like to ask whether there is a relationship among cavitation, net positive suction head, and required net positive suction head, and what each of them represents

NPSH refers to the difference between the total head of the liquid at the pump inlet and the pressure head required for the liquid to vaporize. It is expressed in meters (of water column) and denoted as (NPSH). It can be classified into the following types: NPSHa – also known as available NPSH; the higher this value, the less likely cavitation will occur； NPSHr —— pump net positive suction head, also known as the required net positive suction head or the dynamic pressure drop at the pump inlet; the lower this value, the better the pump’s resistance to cavitation ； NPSHc —— Critical net positive suction head, refers to the net positive suction head at which the pump’s performance declines by a certain amount ； ——The allowable NPSH is the value of NPSH used to determine the operating conditions of a pump; it is usually set at (1.1–1.5)NPSHc. When the pump is in operation, the liquid at the inlet of the impeller develops vapor under a certain vacuum pressure. These vaporized bubbles, due to the impact of the liquid particles, cause erosion of the metal surfaces such as those of the impeller, thereby damaging them. This vacuum pressure is known as the vaporization pressure. The NPSH refers to the excess energy per unit weight of liquid at the pump’s inlet that exceeds the vaporization pressure. The unit is meters of liquid column, denoted as (NPSH)r. The suction lift is the required net positive suction head Δ/h: it represents the vacuum level at which the pump can draw in liquid, or in other words, the maximum geometric installation height permitted for the pump. The unit is meters. Suction lift = Standard atmospheric pressure (10.33 meters) – NPSH – Pipeline losses – Safety margin (0.5). Standard atmospheric pressure can create a vacuum height of 10.33 meters in the pipeline