Can a multistage centrifugal pump automatically absorb water? To answer this question, Zoomlian Pump Industry, a manufacturer of multistage centrifugal pumps, has provided the following detailed explanation. The working principle of a multistage centrifugal pump is that the high-speed rotation of each stage of impellers performs work on the liquid respectively. The energy of the liquid increases with each stage. When the energy reaches a relatively large value at the tail impeller, the entire energy conversion is completed. In this process, the liquid enters from the root of the quasi-axis of the blade, obtains high pressure through the centrifugal force generated by the high-speed rotating blade, and flows out from the pressure relief port. Since the centrifugal pump relies on the vacuum generated by centrifugal force to suck water into the pump body, if there is air communication, it is impossible to form enough vacuum to make the medium pressed into the impeller by the external atmospheric pressure. Therefore, the multistage centrifugal pump generally does not have the ability of automatic water absorption.
The structural characteristics of the multistage centrifugal pump also determine that it does not have self-priming capacity. The multistage centrifugal pump is formed by combining two or more impellers with the same function into a series structure, which is equivalent to the effect of multiple single-stage centrifugal pumps in series. This structure makes the multistage centrifugal pump show that the pressure relief port of the first-stage medium is connected to the inlet of the second stage, the pressure relief port of the second-stage medium is connected to the inlet of the third stage, and so on in the fluid channel. This series structure enables the multistage centrifugal pump to significantly increase the head, but at the same time limits its self-priming capacity.
To sum up, the multistage centrifugal pump itself does not have self-priming capacity. If it is necessary to use a centrifugal pump under self-priming conditions, a self-priming pump with self-priming capacity can be selected. At the same time, it is also possible to try to improve its self-priming capacity by attaching an air-extracting and water-leading device to the multistage centrifugal pump, but these methods usually have limited effects and high costs.