The working principle of the jet pump: When the working fluid Qo is ejected from the nozzle at high speed, a vacuum is formed at the entrance of the throat because the surrounding air is swept away by the jet, and the transferred fluid QS is sucked.
The advantages of jet pump:
1. Simple structure, small size, light weight and low price;
2. It is convenient for on-site processing, easy to install, and simple to maintain;
3, no moving parts, easy to open and close, when the suction port is completely exposed to the water surface, there is no danger when the flow is cut off;
4. Sludge or other liquids containing particles can be lifted;
5. It can work in series with centrifugal pumps to get water from large wells or deep wells.
The disadvantage of jet pump is its low efficiency. Generally used in water supply and drainage engineering:
1. Used as a pumping and water diversion device for centrifugal pumps, connect a jet pump on the top of the pump casing of the centrifugal pump. Before the pump starts, the high-pressure water from the external water supply pipe can be used to suck the air in the pump through the jet pump to start the centrifugal pump. The purpose of pre-pumping water.
2. The jet pump is used to pump liquid chlorine and alum in the water plant, commonly known as "water mice".
3. In the oxygenation process of groundwater de-ironing and aeration, the jet pump is used as an air-carrying and inflating device. The jet pump is always sucking air, and the water and air are mixed through the mixing pipe to achieve the purpose of oxygenation. This kind of water and gas jet pumps are generally called gas filling valves.
4. Used as a pump for stirring and mixing sludge in the sludge digestion tank in the drainage project. In recent years, the use of jet pumps as aeration equipment for biological treatment and aerated water equipment for air flotation purification has developed extremely rapidly.
5. Work in conjunction with a single-stage centrifugal pump to increase the suction height of the centrifugal pump device. As shown in Figure 3.20, a jet pump is installed at the end of the suction pipe of the centrifugal pump, and the pressure water pressed out by the centrifugal pump is used as the working liquid, so that the centrifugal pump can lift the liquid from the well as deep as 30-40m. At present, this kind of joint working device is common, and it is suitable for areas with deep groundwater level or pastoral areas to solve people's domestic water, livestock water and small area of farmland irrigation water.
6. In the earthwork construction, it is used for well points to lower the groundwater level of the foundation pit, etc. As shown in the figure below:
