Self-priming pumps for water: device, principle of operation, rules of operation

Self-priming type pumps are a special type of surface equipment designed to increase the working life. Their moving parts are always cooled, the seals are intact, the motor operates flawlessly. However, due to the solid range it is difficult to dwell on a suitable model. Do you agree?

All you need to know about self-priming pumps for water, you will find on our website. We set out in detail the principle of the device and operation of units of this type, the differences in the design are given. The information provided by us will help you make a balanced purchase.

We described in detail the various options for self-priming pumps, gave recommendations for operation. Useful photo and video applications to deepen knowledge.

Features of self-priming units

When purchasing a unit for use in a country plot, a number of factors that determine the desired category should be analyzed.

These include:

• source depth;
• distance from the source to the house;
• pressure level;
• water quality;
• water consumption.

Typically, these data are taken into account when calculating the performance of the device, but they are also useful when choosing a pump by the type of suction.

There are self-priming and normal suction devices. The difference lies in the design that regulates the process of refilling in case of ingress of air into the system.

Normally suction include submersible and semi-submersible pumps, the operation of which occurs if the fluid from the source moves into the working compartment by gravity. When air enters, the automatic protection against “dry running” is triggered and the work stops, as the machine does not work in idle mode. The pump has to restart.

Self-priming models are designed for independent air removal without human intervention. This is due to the design features: in the upper part of the working compartment there is a plunger through which air is removed. Back valve prevents him back.

Modern versions with built-in valves produce self-refilling, thus eliminating the need for constant monitoring of equipment.

A small lifting height of self-priming units is also associated with the refilling process - up to 9 m. It is important to ensure that the working chamber was constantly filled with water, and the shorter the supply line, the faster the process of moving water.

Most often, self-priming pumps are part of a pumping station with a hydraulic accumulator, suction port (or ejector), stop valves and instrumentation.

Proper installation of the suction line

With water supply system Not only the installation of a self-priming pump or pumping station is important, but also the installation of a suction line.

When creating a sealed water supply, you should check the ratio of the diameter of the pipeline with the diameter of the nozzle, as well as shorten the length of the entire pipeline (if possible).

The longer the suction line, the higher the resistance, respectively, the lower the pressure. The presence of leaks can lead to equipment breakdown - this condition is relevant for centrifugal models that are not designed for pumping air-to-liquid media.

Pay attention to the location of the pipes. The suction line should not have kinks, kinks, complex assembly structure, rising above the level of the pump, in Otherwise, air closures may form, which interfere with the suction process and are difficult to remove from the system.

As additional equipment installed directly on the highway, use check valve (or a simple non-returnable counterpart) and filter. Thanks to the valve, water is retained in the pipeline and does not flow back, thereby protecting the owner of the pump from repeated fillings.

The filter protects the equipment from the ingress of bottom sediment with large inclusions, pieces of aquatic plants, clay impurities.

Is it possible to replace the self-priming model with a conventional pump? If there is no other way out, then they do it - at the time of repair or purchase of new equipment.

However, do not forget about some of the nuances:

• it is necessary to completely fill the pump chamber and main with water before switching on;
• Avoid exposure to air, otherwise the equipment will fail;
• filling should be done after each "accident" caused by depressurization of the water supply system.

Practice shows that users of self-priming pumps are not in a hurry to switch to conventional ones, especially since the choice of equipment is often dictated by optimal suction conditions.

Centrifugal self-priming pumps

A suitable option for autonomous use in a private country plot is a centrifugal self-priming pump that pumps not only clean water, but also medium with small inclusions - for example, sediment from the pond.

He copes with the liquid, which is a mixture of water and gas. The equipment is superficial, that is, it is installed above the water mirror, and the process of rising water is provided by an internal vacuum in the suction line.

Types of structures and their features

Familiarizing yourself with the self-priming centrifugal pump device is essential for troubleshooting and regular maintenance. The unit is an uncomplicated mechanism, enclosed in a durable spiral housing with a cover, the case material is stainless steel, cast iron, plastic.

Inside is an impeller (steel or polymer), equipped with blades deployed in the opposite direction. In addition to the impeller, an important part is a diffuser and an ejector (venturi tube).

Thus, almost all the details are static, and the movement sets a single dynamic element - the impeller disk (s).

The design of the pump implies easy access to the main part for routine inspection or minor repairs (for example, cleaning or turning). Since the device is located outside, unlike the submersible counterpart, there is always the opportunity to inspect it and replace parts.

Centrifugal models are more massive than vortex ones, but they work much quieter and are able to pump dirty water with inclusions of middle fraction. For highly polluted environments, special drainage pumps are used, and if additional grinding is necessary - fecal ones.

When choosing a unit from a supplier, ask about the possible configuration: in addition to the electric motor use gasoline or diesel, but for country performance electrical equipment more optimally. With regular routine inspections and maintenance, the life of a centrifugal pump reaches 20 years.

Characteristics of the models vary, but the average may look like this:

• temperature inside the system - up to + 35ºС;
• air temperature outside (at the pump installation site) - up to + 35ºС;
• lifting height of the suction line - up to 8 m;
• the highest pressure in the system is 6 bar;
• the motor is a bipolar asynchronous (protection class not lower than IP 44).

Most of the parts are made of stainless steel, as the material of the end seal using graphite or ceramics.

Thus, the self-priming unit is very similar in structure to the usual centrifugal pump, with one difference: the process of recirculation of liquid occurs inside the housing, and not in the remote line.

The plugs for filling and unloading water, the support for mounting to the engine, the location of the pipes connecting the device with the pressure and suction pipe are like simple equipment.

Features and principle of operation

At the nozzle, water flows from the suction pipe into the body and fills the entire space, after which the impeller is automatically activated. Under the influence of centrifugal force, the liquid is displaced from the center to the peripheral areas and under pressure moves into the pressure line, also attached through the pipe.

With a decrease in pressure in the central part, water is sucked back into the housing from the suction pipe. The frequency of suction-ejection and underlies the continuous supply of water by centrifugal equipment.

The number of impellers in the pumps may be different, from one to several (single-stage and multistage), however, the principle of pumping fluid into the housing and further along the line does not is changing.

Scope of centrifugal units

Centrifugal self-priming apparatus capable of pumping fluids that can not cope with the model of the vortex type:

• viscous media;
• liquids with solid particles;
• abrasive fluids.

In this regard, this category of pumping equipment is often used in production, for example, for pumping petroleum products. In private use, the unit will not stagnate if the owners use a dacha pond or other body of water for irrigation of a garden or vegetable garden, whose water is not very clean and transparent.

The device is able to move the liquid with bottom thick sediment, pieces of mud and other aquatic plants.

Household pumps do an excellent job with the transfer of clean water, so they are good for the device of autonomous water supply of the building and adjacent buildings (baths, summer kitchen). The pump, powerful on productivity, is suitable for the equipment of rational system of watering not only beds, but also a lawn, a hothouse economy, flower beds and a garden.

At start-up, the process of self-priming of the water pipeline takes place, which allows saving money on maintenance and guarantees stability of work.

Vortex impeller pumps

Among self-priming modifications, there is a group of vortex pumps, however, unlike centrifugal analogues, they are not suitable for pumping viscous media.

The presence of solid inclusions in water must be excluded, otherwise the equipment’s performance will be impaired. Vortex type pumps are simple to set up and maintain, but they have lower capacity and lower efficiency.

The scheme of the device and the principle of operation

Internal parts of the vortex pump differ little from analogues of centrifugal equipment. The main dynamic part is the working disk wheel, equipped with blades arranged in a circle.

The blades rotate inside a kind of channel associated with the inlet and outlet nozzles. The liquid flows through the suction nozzle, under the influence of the rotation of the wheel twists and moves along the helical path in the direction of the exit.

Multiple presence of fluid in the space between the blades forms additional energy and pressure, raising the water to the required level, the principle of the self-suction vortex operation is based on this the pump.

The intake air is mixed with the liquid, then the mixture is again divided into two components: the air is discharged outside, and the liquid continues to circulate in the working chamber. After all the air has been removed, the chamber is completely filled with water and put into operation on the principle of centrifugal equipment.

Mandatory element, as with centrifugal equipment, is a check valve that performs two functions:

• prevents the return of air;
• provides filling of the working chamber with water.

The maximum height of the rising water, which provides vortex self-priming equipment - 8 meters. Vortex pumps differ from centrifugal pumps by two principal qualities: they do not pump dirty media, but they do an excellent job with moving a mixture of air and liquid.

Low efficiency (from 25% to 45%) is due to the fact that a lot of energy is spent on the process of pumping fluid. For this reason, the owners of suburban areas prefer centrifugal units. Vortex equipment is usually remembered when it is not possible to install a more productive counterpart.

Household benefits

The advantage of this category of self-priming pumps are compact size and increased head (5-7 times more than that of centrifugal devices). Thus, it is rational to use them when servicing a water source located far from water points, provided that greater performance is not needed.

An example would be pumping water from the well, lifting height in which does not exceed 7-8 m, in the so-called "working area", where garden plantings, beds, greenhouses are usually located. Given the uneven terrain and rounding of the country buildings, you should count on a pipeline up to 100m long, which means that you will need a lot of pressure.

In addition to the use of vortex modifications in autonomous private water mains, they are used to extinguish fires, ventilation devices, in thermal installations.

Ejector - device for deep sources

Self-priming pumps with built-in ejector designed for open natural reservoirs, wells and wells, the depth of water in which does not exceed 7 m or 8 m.

Usually the technical characteristics of this category of equipment are reduced to the following parameters:

• productivity - 4-5 m³ / h;
• pressure - 4-6 bar;
• head - 50-60 m.

Together with the hydroaccumulator, pressure switch and a set of automation such modifications form efficient pumping stations. At a certain distance from the building, where the main points of water pumping are located, there is little surface self-priming equipment, an additional mechanism is required.

You can increase the suction power when using outboard ejector which copes with the rise of water, located at a depth of 35-40 m. Industrial models of ejectors are able to work effectively, if the water mirror is at a depth of 19-20 m. The far distance to the source is also not an obstacle to the ejector devices.

When using a remote ejector, the efficiency of the pumping station drops dramatically - up to 30-35%, but the noise level characteristic of built-in ejectors decreases.

Conclusions and useful video on the topic

The presented video materials will help you to understand the design and principle of operation of self-priming equipment.

Movie # 1. Assembly of the pump from the company "Asterion" (series UP):

Movie # 2. The principle of operation of the centrifugal self-priming pump:

Movie # 3. Professional overview of Aquario pumps (AJC series):

Centrifugal and vortex self-priming pumps - the most suitable equipment for private use in suburban areas. With their help, you can create a water supply or irrigation system.

But remember that maximum efficiency can be achieved only by carefully analyzing the conditions of use of the pumping station and studying the technical characteristics of the selected model.

We are waiting for your stories about personal experience of pumping water with a self-priming pump. Comments, please leave in the box below. Here you can ask questions on points of interest and share useful facts.