What is pump self-priming? What is the self-priming capacity of a self-priming centrifugal pump?
Self-priming, as the name implies, self-priming means: before pumping water, the self-priming centrifugal pump can automatically suck up water without filling the water pipe. The principle is: when the suction pipe of the water pump is filled with air, the negative pressure (vacuum) formed when the pump is working is used to raise the water pressure lower than the suction port under the action of atmospheric pressure, and then discharge it from the drain end of the water pump. When there is air in the suction pipe of the water pump, the negative pressure (vacuum) formed when the water pump is working is used to raise the water pressure lower than the suction port under the action of atmospheric pressure, and then discharge it from the drain end of the water pump. Before this process, there is no need to add "diversion water (water for guiding." A pump with this ability is called a "self-priming pump." The self-priming of a self-priming pump means that there is no medium in the pump cavity when it is running dry. The self-priming capacity of any pump cannot be greater than 76 cmHg. Generally speaking, the self-priming capacity is the ability of the pump to absorb water.
Schematic diagram of pump self-priming
Some centrifugal or rotary vane pumps must add "diversion" to form a closed environment in the pump cavity before absorbing water, and then the pump can run to form negative pressure to achieve the purpose of water absorption. For example, the manual pump used in rural areas before. For pumps without self-priming ability, it is very troublesome to add "diversion" before each suction.
Suction capacity is that the centrifugal pump produced in this way uses the centrifugal force generated by the water to rotate the impeller to work. Before the pump is started, the pump casing and suction pipe must be filled with water, and then the motor is started, so that the pump shaft drives the impeller and water to make a high-speed rotation movement. Under the action of centrifugal force, the water is thrown to the outer edge of the impeller and passes through the volute pump casing. The flow channel flows into the pressurized water pipeline of the water pump. At the center of the pump impeller, because the water is thrown out under the action of centrifugal force to form a vacuum, the water in the suction pool is pressed into the pump casing under the action of atmospheric pressure, and the impeller rotates continuously, making the water in the impeller Under the action of continuous inflow and outflow, the purpose of water delivery is achieved. The high heart pump itself has no self-priming ability. In order to expand the scope of use of centrifugal pumps, special measures are taken to manufacture supervised self-priming centrifugal pumps, or a suction and water diversion device is attached to the centrifugal pump to make it have a purpose.
