Ejector for a pumping station: operating principle, device, installation rules

The deep occurrence of an aquifer is a common problem that is familiar to many land owners. Conventional surface pumping equipment either cannot supply the house with water at all, or feeds it into the system too slowly and with a low pressure.

This problem requires a speedy resolution. Agree, buying a new pump is an expensive and not always financially justified undertaking. The solution to this situation may be an ejector for a water pumping station.

We will tell you how to choose a suitable unit and install it without the help of specialists. And also give step-by-step instruction on the manufacture and connection of a homemade ejector. All stages of the work are accompanied by visual photographs.

The principle of operation of the ejector

The deeper the water is, the more difficult it is to raise it to the surface. In practice, if the well’s depth is more than seven meters, surface pump copes with its tasks with difficulty.

Of course, for very deep wells it is more appropriate to purchase a high-performance submersible pump. But with the help of an ejector, it is possible to improve the characteristics of a surface pump to an acceptable level and with significantly lower costs.

Ejector - the device is small, but very effective. This unit has a relatively simple design, it can even be made independently from improvised materials. The principle of operation is based on giving the water stream an additional acceleration, which will increase the amount of water coming from the source per unit time.

This solution is especially convenient for those who are going to install or have already installed pumping station with surface pump. The ejector will increase the depth of water intake to 20-40 meters.

It should also be noted that the acquisition of more powerful pumping equipment will lead to a noticeable increase in energy consumption. In this sense, the ejector will bring noticeable benefits.

The ejector for a surface pump consists of the following elements:

• suction chamber;
• mixing unit;
• diffuser;
• narrowed nozzle.

The operation of the device is based on the Bernoulli principle. It states that if the speed of the flow increases, an area with low pressure is created around it. Thus, a rarefaction effect is achieved. Water enters through a nozzle whose diameter is smaller than the size of the rest of the structure.

This scheme allows you to get an idea about the device and the principle of operation of the ejector for the pumping station. Accelerated return flow creates a low pressure area and transfers kinetic energy to the main water stream

A slight narrowing gives the flow of water a noticeable acceleration. Water enters the mixer chamber, creating an area with reduced pressure inside it. Under the influence of this process, a stream of water under a higher pressure enters the mixer through the suction chamber.

Water does not come into the ejector from wellsbut from the pump. Those. the ejector must be installed so that part of the water raised by the pump returns to the ejector through the nozzle. The kinetic energy of this accelerated flow will be continuously transmitted to the mass of water that is absorbed from the source.

To create a region of rarefied pressure inside the ejector, a special fitting is used, the diameter of which is smaller than the parameters of the suction pipe

Thus, a constant acceleration of the flow will be ensured. Pumping equipment will need less energy to transport water to the surface. As a result, its effectiveness will increase, as will the depth with which water can be taken.

Part of the water produced in this way is again sent to the ejector through the recirculation pipe, and the rest goes to the water supply system of the house. The presence of an ejector has another plus. It absorbs water independently, which additionally insures the pump from idling, i.e. from a “dry running” situation, which is dangerous for all surface pumps.

The diagram shows the device of an external ejector: 1- tee; 2 - fitting; 3 - adapter for a water pipe; 4, 5, 6 - corners

To regulate the operation of the ejector, use a conventional crane. It is installed on the recirculation pipe, through which water from the pump is directed to the ejector nozzle.Using a tap, the amount of water entering the ejector can be reduced or increased, thereby reducing or increasing the rate of return flow.

Choices: built-in or external?

Depending on the installation location, remote and built-in ejectors are distinguished. There is no big difference in the design features of these devices, but the location of the ejector still affects in some way both the installation of the pumping station and its operation.

So, built-in ejectors are usually placed inside the pump housing or in close proximity to it. As a result, the ejector takes up a minimum of space, and it does not have to be installed separately, it is enough to perform the usual installation of the pump station or the pump itself.

In addition, the ejector located in the housing is reliably protected from contamination. Depression and return of water is carried out directly in the pump casing. No need to install additional filters to protect the ejector from clogging with silt particles or sand.

A remote ejector for a pumping station is more difficult to install than an internal model, but this option creates a much smaller noise effect

However, it should be remembered that such a model demonstrates maximum efficiency at shallow depths, up to 10 meters. Pumps with a built-in ejector are designed for such relatively shallow sources, their advantage is that they provide excellent pressure to the incoming water.

As a result of these characteristics, it is enough to use water not only for domestic needs, but also for irrigation or other business operations. Another problem is the increased noise level, since the sound effect of the water passing through the ejector is added to the vibration of the running pump.

If you decide to install a pump with a built-in ejector, you will have to take care of sound insulation especially carefully. Pumps or pumping stations with a built-in ejector are recommended to be installed outside the house, for example, in a separate building or in a well box.

The electric motor for the pump with an ejector should be more powerful than for a similar ejectorless model.

A remote or external ejector is installed at a certain distance from the pump, and this distance can be quite significant: 20-40 meters, some experts even consider the figure of 50 meters acceptable. Thus, the remote ejector can be placed directly in the water source, for example, in the well.

An external ejector does not so much increase the productivity of the pump, but rather aims to increase the depth of water intake from the source, which can reach 20-45 m

Of course, the noise from the work of the ejector, installed deep underground, will no longer bother the residents of the house. However, this type of device should be connected to the system using a recirculation pipe through which water will return to the ejector.

The greater the depth of installation of the device, the longer the pipe will have to be lowered into the well or well.

The presence of one more pipe in the well is best foreseen at the design stage of the device. The connection of a remote ejector also provides for the installation of a separate storage tank, from which water will be taken for recirculation.

This tank allows you to reduce the load on the surface pump, saving some energy. It is worth noting that the efficiency of the external ejector is slightly lower than that of the models built into the pump, however, the ability to significantly increase the depth of the fence makes us come to terms with this drawback.

When using an external ejector, there is no need to place pumping station directly near the water source. It can be installed in the basement of a residential building. The distance to the source can vary between 20-40 meters, this will not affect the performance of the pumping equipment.

Features of mounting the device

As already mentioned, the installation of an ejector built into the pump does not cause any special problems, since the device is already in the device body. The surface pump is simply connected to the water supply hose on the one hand, and also to the water supply system on the other hand.

If it is used as part of a pumping station, then the pump is connected to accumulator by means of a special fitting for five exits. In addition, the pump will need to be connected to the contacts of the pressure switch to ensure its automatic on and off.

This diagram illustrates the procedure for connecting a remote ejector to a pump station, indicating the installation locations of all the necessary nodes

Before switching on the surface pump, it must be filled with water through the filling hole provided for this. Do not turn on such equipment without water; it can burn out. If the pump is installed correctly, the ejector will work without interruption.

But the installation of the remote ejector is made according to a more complex scheme. To begin with, it will be necessary to install a pipe that will provide a reverse flow of water from the drive to the ejector. On the suction section of the ejector set check valve. A strainer should be placed behind it to protect the device from clogging.

On top of the recirculation pipe, an adjustment valve must be installed to adjust the amount of water that is sent to the ejector. This site is not mandatory, but can significantly improve the situation with the pressure of water in the house.

The less water will return to the ejector, the more it will remain for the plumbing system at home.

The ejector is assembled before operation according to the standard scheme. A strainer is connected from below to the ejector body, and from above - through a nozzle a Venturi tube made in the form of a plastic bell (+)

In this way, you can influence water pressure in the water supply. If it is lacking, tighten the control valve on the return line a little.

If the pressure is too large and creates an unnecessary load on the water supply system, it makes sense to send more water to the ejector to increase the efficiency of the pumping equipment.

Some industrial models of ejectors are already equipped with a system of such adjustment. The instructions that come with the device usually describe in detail how to set up the ejector.

Using a homemade external option

The built-in ejector is usually purchased simultaneously with the pump, but the external model is often made with your own hands.

It will be useful to consider the creation process and how to connect such a device. In order to make an ejector, you will need details such as a tee with internal threaded connections, a fitting, fittings, bends, couplings, etc.

DIY ejector assembly

Assemble the device as follows:

1. Connect the bottom of the tee to the fitting so that the outlet pipe is at the top, and the fitting with a smaller diameter is inside the ejector.
2. Then you need to refine the design, cutting off the narrow part of the fitting, if it protrudes from the tee.
3. If the fitting is too short, it is expanded using a polymer tube.
4. An adapter with an external thread is screwed onto the upper side of the tee.
5. A PVC water pipe is connected to the other end of the adapter using a fitting.
6. Now, to the bottom of the tee, in which a narrow fitting is already inserted, you should attach an outlet in the form of a corner.
7. A pipe is connected to this branch, through which a return flow of water to the ejector will come.
8. Another corner is connected to the side pipe of the tee.
9. A pipe is connected to this corner with a collet clamp, water from a well, a well, etc. will be sucked through it.

The distance between the edge of the tee and the fitting should be approximately 2-3 mm.This will ensure the creation of a vacuum region with the necessary characteristics. A clamping nut is used to secure the recirculation pipe.

It turns out that two elements are simultaneously connected to the internal thread of the lower branch pipe of the tee. One of them (fitting) is inside the tee, and the second (corner) is outside. In order for both of them to fit on the same threaded connection, cut off part of the thread of the fitting.

Of course, all threaded connections must be sealed and sealed. Most often, FUM tape is used for this. Sometimes to connect the ejector to pumping station not metal-plastic pipes are used, but structures made of polyethylene.

For their installation, special crimping elements should be used, and collet clamps, which are good for metal plastic, will not work in this situation.

All threaded connections of the ejector should be carefully sealed and sealed, for example, using FUM tape or other suitable material

Pipe Connection Procedure

About which pipes will be used to connect a remote ejector, you should think in advance. Polyethylene structures bend well when heated, which eliminates the need for corners when connecting an ejector. The pipe is simply bent in a suitable place and at the right angle, and then attached to the ejector.

To connect the ejector, you can use pipes made of polyethylene, which are easier to install than similar structures made of metal-plastic

So, the device has three outputs, each of which should be connected to the corresponding pipe. First, a pipe is usually installed through which water will be drawn from the source. She joins the side exit of the ejector.

At the end of this pipe, a non-return valve, as well as a strainer, are mandatory. This pipe should be long enough to sink deep under the water. But you should not draw water at the very bottom of the source, as this can lead to clogging of the ejector, even despite the presence of a filter.

Then you can attach the pipe to the lower end of the ejector, in which a narrowed fitting is installed. This is the highway through which water is recycled. The second end of this pipe should be connected to a container from which water will be drawn to create a reverse flow.

The third pipe is an ordinary water main. At one end, it is mounted on the upper nozzle of the ejector, and the other is attached to the surface pump. It should be remembered that the diameter of the pipe through which water is drawn from the source must exceed the dimensions of the pipe through which water is supplied to the ejector.

Three pipes are connected to the remote ejector: a pipe for sucking water from the source, a pipe connecting the device to the pump, and a line for water recirculation

If an inch pipe is used in the feed, it is recommended to take the pipe a quarter of an inch larger for suction. After all the connections are completed, the ejector is immersed in water.

Before starting the system for the first time, it must be filled with water. The pump is poured through a special hole. Pipes leading to the ejector must also be filled with water.

Before starting the pump station with an ejector, it is necessary to fill the surface pump with water, as well as all pipes connected to the ejector

Start-up and further operation

The initial start-up of the pump station is recommended as follows:

1. Pour water into the pump through a special hole.
2. Turn off the tap through which water flows from the pump station to the water system.
3. Turn on the pump for about 10-20 seconds and immediately turn it off.
4. Open the tap and bleed part of the air from the system.
5. Repeat the cycle of short on / off switching of the pump in combination with air bleeding until the pipes are filled with water.
6. Switch on the pump again.
7. Wait until the accumulator is full and the pump shuts off automatically.
8. Open any water tap.
9. Wait until the water flows out of the accumulator and the pump starts automatically.

If water did not flow when starting up the system with an ejector, it is possible that air leaks into the pipes somehow, or the initial filling with water was not performed correctly. It makes sense to check the presence and condition of the check valve. If it is not there, the water will simply pour into the well, and the pipes will remain empty.

These points should be taken into account when using a pump station with an ejector, which starts after long-term storage. Check valve, pipe integrity and tightness of the connections are best checked immediately.

The lower nozzle of the ejector, through which water is drawn, should be protected from contamination with a strainer (+)

If everything is in order, and water does not enter, you need to check the voltage supplied to the pump station. If it is too low, the pump simply cannot run at full capacity. The power supply to the equipment should be normal and the problem will disappear.

If an ejector is needed to improve the pressure of the water in the system, and not to increase the depth of water intake, you can use the above-described model of a homemade ejector.

But it does not need to be immersed in water, it can be placed in a convenient place near the surface pump. In this case, the ejector will work in much the same way as the built-in model of industrial production.

Conclusions and useful video on the topic

In this video material, the issue of suction depth of a surface pump and options for solving the problem using an ejector are discussed in detail:

The principle of operation of the ejector is clearly demonstrated here:

An ejector is a simple but very useful device. This is a convenient and practical way to improve the performance of pumping equipment in a private house. But the installation of the ejector, especially the remote model, must be done correctly, the only way to ensure a noticeable increase in water pressure.

To all those interested in the issue of choosing and connecting an ejector, we suggest joining the discussions and leaving comments on the article. The comment form is below.