Do not need to be filled with liquid in the pipeline is filled with liquid can automatically pump
water pumping up the pipeline centrifugal pump called
self priming pump. Self priming pump structure of many types, of which, the external mixing type self priming pump working principle is: before starting the pump in the pump casing filled with water (or pump water inside the shell itself there is water). After the start of the high-speed rotation of the impeller to the flow in the impeller channel to the vortex shell, then the entrance to form a vacuum, so that water backstop the door open, suction tube of air into the pump and the impeller channel to reach the outer edge.
On the other hand, by separating gas and water into the impeller chamber and the water flow by about hole to return to the outer edge of the impeller. After the left back hole flows back to the water in the role of pressure difference and gravity, shooting at the impeller channel, and was crushed impeller, and inhalation of air pipes to a mixture of swing to scroll to the rotation direction of the flow. And then right to water in the backwater hole converging flow along the spiral flow.
Due to the constant impact of the liquid in the case of the blade cascade, and constantly being crushed by the impeller, with the strong mixing of the air, the formation of a mixture of water and gas, and constantly flow so that the gas can not be separated from the water. The mixture was separated at the volute tongue export stripping along the short tube into the separation chamber. In the separation of indoor air is separated from the outlet pipe to drain, while the water is still by the left and right of the backwater hole flow to the outer edge of the impeller and and the suction pipe air mixed phase. So repeated cycle, gradually will be sucked into the pipeline in the air exhaust, so that water into the pump, complete the self absorption process.
Within the mixed type self-priming pump, working principle and the mixed type self-priming pump are the same, and the difference is just does not flow to the outer edge of the impeller of the backwater, and flows to the impeller inlet. Internal mixing type self priming pump in the start, must open the impeller before the bottom of the return valve, so that the pump liquid flow back to the impeller inlet. The water is mixed with the air in the suction pipe under the action of the high speed rotation of the impeller to form a gas water mixture to the separation chamber. Here the air is discharged and the water is returned from the return valve to the impeller inlet. So repeatedly, until the air exhausting, suction Sheung Shui to come.
Since the height of self suction pump, and the impeller clearance before sealing, pump rpm, separation chamber liquid height and other factors. The smaller the impeller seal clearance, the greater the self suction height, generally take 0.3~0.5 mm; in the gap increases, in addition to the self suction height, the pump head and efficiency are reduced. The pump self-priming height increased with the increase of the circumference of the impeller speed U2, but to the largest self-priming height and speed increase and self-priming height did not increase, but at this time to shorten the time of self - priming; when the rotation decline self-priming height is decreased. In the case of other conditions unchanged, the height of the self absorption is also increased with the increase of the height of the water storage (but can not be more than the best reservoir water storage height). In order to self-priming pump better the mixture of gas and water, the impeller blades to be less, cascade section distance increases; and should adopt the semi open impeller (or impeller channel wide impeller), which is more convenient in - depth into the backwater cascade of impeller. Self suction pump supporting most of the internal combustion engine, mounted on a mobile small car, suitable for field work.
