Self-priming pumps are divided into the following categories based on the principle of action: 1. Gas-liquid mixing (including internal mixing and external mixing); 2. Water ring wheeled; 3. Jet (including liquid jets and gas jets). The working process of the gas-liquid hybrid self-priming pump: due to the special structure of the self-priming pump body, after the pump stops, a certain amount of water is stored in the pump body. After the pump is started again, the air and water in the suction pipeline are sucked due to the rotation of the impeller. Fully mixed and discharged to the air-water separation chamber. The gas in the upper part of the air-water separation chamber overflows. The lower part of the water returns to the impeller and mixes with the remaining air in the suction pipeline until the gas in the pump and the suction tube is completely discharged. Suction, and normal pumping. The water ring wheel type self-priming pump combines the water ring wheel and the water pump impeller in a shell and discharges the gas through the water ring wheel to achieve self-priming. When the pump works normally, the passage of the water ring wheel and the pump impeller can be cut off by the valve and the liquid in the water ring wheel can be drained. Jet self-priming pump, which is a combination of a centrifugal pump and a jet pump (or ejector), relying on a spray device to create a vacuum at the nozzle to achieve suction.
According to the pump's supporting power machine type, it is divided into a motor supporting self-priming pump and a diesel engine supporting self-priming pump.
According to the structure and working characteristics of achieving self-priming function, it can be divided into inner slide type, outer slide type, water ring type and other types. There are direct drive (including inner shaft) and belt drive. Imported diameter 25 to 200 mm.
The operating principle of the external mixing self-priming pump is that the pump is filled with water (or the pump housing itself contains water) before the pump starts. After starting, the impeller rotates at a high speed so that the water in the impeller channel flows toward the volute. At this time, the inlet forms a vacuum, so that the inlet reverse door is opened, the air in the suction pipe enters the pump, and reaches the outer edge through the impeller channel. On the other hand, the water discharged from the impeller into the air-water separation chamber flows back through the left and right water-return holes to the outer edge of the impeller. The water flowing back from the left backwater hole is directed into the impeller channel under the influence of pressure difference and gravity, and is broken by the impeller. After being mixed with the air from the suction pipeline, the water is thrown toward the volute and flows in the direction of rotation.
Internal mixing type self-priming pump works in the same principle as the external mixing self-priming pump.
Most of the self-priming pump is matched with the internal combustion engine, and it is mounted on a movable trolley and is suitable for field operations.