Victor Pump- Model S Series - Self-Priming Centrifugal Pumps - Brochure

The pump is normally placed dry above or aside the liquid. In these cases the suction line contains air. The self-priming pump will evacuate all the air. The vacuum produced as the impeller rotates 2 draws air 1 into the pump where it is mixed with the liquid already contained in the pump casing. The air/liquid mixture is driven to the discharge side where the air separates out and is expelled through the discharge port 3 while the liquid, due to the higher gravity, falls back and is reused in the suction side through a small passage. When all the air has been evacuated from the suction line the liquid is pumped, even if air-laden. The high suction port keeps enough liquid inside the casing to allow re-priming any time. The non-return valve in the suction port 4 avoids a backflow of the liquid and reduces priming times.