Weak current College】 【self-priming classification and working principle.

1. self-priming concepts and classifications:

1. self-priming pump is not required in the pipeline filled with water inhalation can automatically put water pumping up called self-priming centrifugal pumps. Most of the internal combustion engine supporting the merits of self-pumping pump, mounted on a movable carriage, appropriate for field work.

2. self-priming structure types are divided into two kinds: mixed-type self-suction pump and intermixing of suck.

2. self-priming works:

1, mixed-type self-suction pump works: pump start before pump shell inside filled with water (or pump case is water within itself). Startup impeller rotating impeller rotation channel in streamwise Vortex shell, then the entry form, into the vacuum backstop doors open, air suction tube into the pump and impeller channel arrives at the outer edge. On the other hand, the impeller to gas and water separation Chamber of water by left backwater hole on the outer edges of the stream back to the impeller. Left backwater hole flow back into the water in the pressure difference and gravity, the impeller grooved, and impeller smash, and the inhalation of air pipe to the left to scroll the flow to the direction of rotation. And then with the right return water hole streams to the convergence of the water, along the spiral flow. Since the liquid in the volute continually impact Cascades, constantly being smashed the impeller, mixing with air strongly, generating gas-water mixture, and continually flows cause gas water cannot be separated. Mixture in a snail shell export was divided tongue split along the short tube into the separation Chamber. In the separation of indoor air is separated by the pipe the water drain, while still having left backwater hole to the outside edge of the impeller and the mixture of air suction tube. So repetition, gradually the inhalation of air exhaust in the pipeline, so that the water pump, complete self priming process.

2, intermixing of self-priming, working principle and external mixing suck the same, the difference is the backwater does not flow to the outer edge of the impeller and the entrance to the impeller. Intermixing suck at startup, open impeller directly below the return valve before, so that the pump impeller of liquid flow back to the entrance. Water in the role of the high speed rotating impeller with suction tube to the mixture of air, gas and water mixture flows into the separation Chamber. Here the air emission and water from the return valve to return to the impeller inlet. So repeatedly until air discharge and suction on the water.

Self-priming pump's suction height, front impeller and seals, pump speed, separation Chamber surface height and other factors. Front impeller seal smaller, larger suction height, generally take 0.3 ~ 0.5 mm; in the gap increases, in addition to suck the height drops, the pump head, efficiency is reduced. Pumps suck the height with the impeller of u2 's circumference speed grows, but the biggest suck the height, speed increase and suck the height is not increased, at this point just shorten suck time; when the speed drops to suck the height as the fall. In other conditions unchanged, suck the height also with water height increases (but do not exceed the separation Chamber of best water height). In order to suck the pump by oneself better in the air-water mixture, the impeller blades required less, make the pitch increases Cascades; and the use of half-open impeller (or impeller channel wide impeller), which is more convenient to return water deeply into impeller blade.