Atmospheric pressure is balanced by 10 meters of water column. A pump installed on the surface theoretically lifts water from a depth of 10 m. In practice, this value is 5–8 meters, since:
- air dissolved in water is released in the suction pipe due to vacuum;
— pipelines have hydraulic resistance;
- the pump is installed at a distance from the well.
The ejector is used in addition to the pump when lifting water from 10 meters or more and to increase the reliability of work when lifting from a depth of 5 meters or more. The ejector is also called an injector, a water jet pump, a hydraulic elevator. This device is sold complete with a pump, or you can assemble it yourself. Spare parts for Wilo for pumps in the NasosKlab online store.
Operating principle
Working water is supplied to the ejector nozzle. As the jet exits the nozzle, it accelerates and enters the mixer. Here the jet creates a vacuum, captures the water that needs to be pumped, and mixes with it. In the expanding part of the device, the speed is damped and the pressure increases. It is easy to see that the ejector is the same pump, but for its work it uses not the mechanical energy of the electric motor, but the mechanical energy of the water jet. Equipping the pump with an ejector turns the pumping station from a single-stage into a two-stage.
The ejector is installed either to the pump at the inlet pipe, or to the water intake unit at the bottom of the well.
In the first case, the pipe from the well is connected to the suction pipe of the ejector. Ejector pressure pipe - to the suction pipe of the pump. Working water is supplied to the nozzle of the ejector from the discharge pipe of the pump. With this scheme, the depth from which the water rises does not increase. But due to the fact that the ejector reduces the difference in the suction pipe of the pump, the pressure in the discharge pipe increases.
In addition, the ejector sucks in not only water, but also the air that is released from the water, which reduces the likelihood of “airing”. The advantage of this scheme is that all the equipment is on the surface. Only a suction pipe with a filter and a non-return valve is installed in the well.
The second option is used in wells with a depth of more than 8 meters. The ejector is placed at the bottom of the well. Two pipes are laid from the pump to the ejector. One pipe of a smaller section supplies working water to the nozzle. Through another pipe, from the pressure pipe of the ejector, water enters the inlet pipe of the pump. This scheme is used in wells up to 16 meters deep. For lifting from greater depths, submersible pumps are used.
How to assemble an ejector
Having understood the principle of operation of the ejector, it is not difficult to assemble it with your own hands, for example, from water fittings.
- A 40 mm tee is taken as a body.
- A filter with a non-return valve is attached to the side outlet.
- A nipple is screwed onto the upper outlet, to which a pressure pipe is attached.
- A futorka is selected to the lower outlet.
- The nozzle uses a 1/2″ threaded fitting.The diameter of the outlet is selected when setting up the device. You can immediately purchase 2-3 fittings with different diameters of the outlet.
- The inlet to the nozzle is made from a 1/2″ barrel.
- The nozzle (fitting) is screwed onto the short thread of the barrel.
- A barrel with a nozzle is screwed into the futorka, and the futorka is screwed into the lower branch of the body.
- The length of the barrel is selected so that the nozzle reaches the nipple of the upper outlet and protrudes beyond the futorka by 20-25 millimeters.
- A lock nut is screwed onto the protruding part of the barrel and a working water supply pipe is connected.
Drawings and diagrams for other designs of ejectors can be found on the Internet.
Checking and setting
To check and adjust, a container with water is required - a bath, a barrel and a source of working water - a water pipe or a pump. Instead of a filter with a non-return valve, a hose is connected to the suction pipe of the ejector. It is also convenient to make the connection to the nozzle with a flexible hose. The pressure port remains open.
The ejector is immersed in the tank, and the working water is turned on. The ejector in this mode sucks in air and ejects a mixture of water and air into the tank. The water is seething. If you close the suction hose with your finger, a vacuum should be felt - the finger sticks to the hose. By changing the diameter of the nozzles (fittings) and moving the nozzle by screwing in or unscrewing the barrel in the futorka, a greater vacuum or saving of working water is achieved. By lowering the end of the suction hose into the water, you can observe how the water is sucked into the ejector and thrown into the container.
Next, you can adjust the ejector to the height of the water rise.A hose is attached to the pressure pipe, which is fixed at the desired height. A non-return valve with a filter is attached to the suction pipe. The ejector is immersed in the tank, and the working water opens. By moving the nozzle along the ejector and changing the nozzles, they achieve such a pressure that water comes out of the pipe with a minimum consumption of working water.
