The pump utilizes an axial liquid-return casing structure. The casing comprises a suction chamber, a liquid reservoir, a volute chamber, liquid return ports, and a gas-liquid separation chamber. Upon startup, the impeller draws in the liquid stored in the suction chamber along with air from the suction pipeline, thoroughly mixing them within the impeller. Driven by centrifugal force, the liquid-entraining the gas-flows toward the outer edge of the volute, forming a band of white foam of a certain thickness and a high-speed rotating liquid ring. The gas-liquid mixture enters the separation chamber through a diffuser. Here, the sudden drop in flow velocity causes the lighter gas to separate from the mixture; the gas rises and is discharged through the pump outlet. The degassed liquid returns to the reservoir and re-enters the impeller through the return ports, where it again mixes with gas drawn from the suction line. Driven by the high-speed impeller, the mixture flows back to the outer edge... This cycle repeats continuously, progressively evacuating air from the suction line until all gas is removed and the self-priming process is complete, allowing the pump to enter normal operation.
Some models feature a cooling chamber at the base of the bearing housing. If bearing heat causes the housing temperature to exceed 70°C, coolant can be circulated through the chamber via any of the cooling fluid connections. Internal sealing to prevent leakage from high-pressure to low-pressure zones is achieved through front and rear seal rings; the front ring is mounted on the pump casing, while the rear ring is mounted on the bearing housing. These rings should be replaced if long-term operation causes wear that compromises pump efficiency or self-priming performance.
