Impeller for the centrifugal pump: role in the design. Types of working wheels of centrifugal pumps Processing the wheel of submersible pumps

At the request of the client, the company "Electrohydromash" will put spare parts for pumps own production: X, Ah, AHP, ANS 60, ANS 130, C569M, C245. As well as to pumps different types: D, 1d, ADV, cm, SD, CNS, VK, K, KM, NKU, COP, NK, SM, FAV, SE, W, NMSH, VNN, and many other pumps. In particular, such nodes are supplied as the rotor assembly, the impeller, the sealing ring, the shaft, the sleeve, the protective, guide machine, the pump housing.

What gives the installation of new spare parts:

Spare parts of pumps are not only extension of the service life of the aggregate, but also significant savings money. It is possible to bring such an example: the pump d 320/50 with a 75 kW electric motor for 5 years of operation on the PDD plumbing decreased by 10%. This led to a slight decline in the supply (from 320 to 304 m3 / h) and pressure (from 50 to 47.5 m). However, the corresponding losses of electricity were very significant: for the year they amounted to 65,700 kW / h, i.e. 45 990 rubles.which significantly exceeds the cost of the new wheel ( 4600 rub.)

Wheel working

In the "General" heading, we consider the working wheels for pumps or impellers, as often they are called. - It is the main working body of the pump. The purpose of the impeller lies in the fact that it converts the rotational energy obtained from the engine to the fluid duct energy. Due to the rotation of the impeller, the liquid in it also rotates and the centrifugal force is valid for it. This force causes the liquid to move from the central part of the impeller to its periphery. As a result of this movement, a vacuum is created in the central part of the impeller. This discharge creates the effect of liquid suction by the central hole of the impeller directly through the suction pipe of the pump.

The fluid, reaching the periphery of the impeller, is thrown into the pressure pipe of the pump under pressure. Outdoor I. inner diameter, the shape of the blades and the width of the working clearance of the wheel is determined by calculations. Working wheels can be different types Radial, diagonal, axial, as well as open, semi-closed and closed. The impellers in most pumps have a three-dimensional design that combines the benefits of radial and axial working wheels.

Types of working wheels

The impeller on its design is open, half-closed and closed. On (Fig. 1), their types are depicted.

Open (Fig. 1a) The wheel consists of one disk and blades located on its surface. The number of blades in such imperts most often there are either four or six. They are very often used where low pressure is needed, and the working medium is polluted or contains oily and solid inclusions. This wheel design is convenient for cleaning its channels. Kpd. Open wheels small and amounts to about 40%. As well as specified disadvantage Open working wheels have significant advantages, they are less damaging and easily cleansed from dirt and plaque in the case of clogging. And further, this design The wheels are characterized by a high wear resistance to the abrasive components of the pumped medium (sand).

Semi-closed (Fig. 1b) The wheel is different from the fact that it does not have a second disk, and the blades of the wheel with a small gap fit directly to the pump body that performs the role of the second disk. Semi-closed wheels are used in pumps intended for pumping strongly contaminated liquids (sludge or precipitate).

Closed(Fig. 1B) The wheel consists of two disks, between which the blades are located. This type of wheel is most often used in centrifugal pumps, as they create a good pressure, and they have minimal fluid leaks from entering the input. Wheels are manufactured in various ways: casting, point welding, riveting, or stamping. The number of blades in the wheel affects the efficiency of the pump in general. In addition, the number of blades affects the steepness operating characteristics. The larger the blades, the less the pulsation of the pressure of the fluid at the outlet of the pump. Exist various methods Planting wheels on the pump shaft.

Types of landing wheels

The seat of the impeller on the motor shaft in single pumps may be conical or cylindrical. If you look at the landing site of the impeller in multistage vertical or horizontal pumps, as well as pumps for wells, then there is a landing place, either cross-tree, or in the form of a hexagon or in the form of a hexagon. On (Fig. 2) depicted working wheels with various species Landings.

Conical (conical) landing (Figure 2a).Conical landing provides simple landing And the removal of the impeller. For the disadvantages of such a landing, it is necessary to attribute a less precise position of the impeller relative to the pump housing in the longitudinal direction than with a cylindrical landing, the impeller on the shaft is rigidly, and it is impossible to move it on the shaft. It should also be said that the conical landing, mainly gives large wheels, which adversely affects the end seals and gland pads.

Cylindrical landing (Fig. 2b).Such a landing ensures the exact position of the impeller on the shaft. Fixing the impeller on the shaft occurs due to one or more pin. Such landing is used in, and. This compound has an advantage in relation to a conical compound due to the more accurate position of the impeller on the shaft. The disadvantages of the cylindrical landing include the need for accurate processing, both shaft pump and the hole itself in the wheel hub.

Landing cross-tree or hexagon (rice 2B and 2D). These types of landings are used most often in. This landing makes it easy to plan and remove the impeller from the pump shaft. She fits the wheel on the shaft in the axis of its rotation. Clauses in the working wheels and diffusers are adjusted using special washers.

Star landing(Figure 2g). Such a landing is used in and where the working wheels are made from of stainless steel. This is the most complex design landingrequiring a very high class processing, both the tree and impeller. It hardens the wheel in the axis of the shaft rotation. Clamps in the working wheels and diffusers are adjustable using sleeves.

There are other types of landings of the impeller on the pump shaft, but we did not put a goal to disassemble everything existing methods. This chapter discusses the types of impeller most frequently used.

Operation, maintenance and repair

As known, working wheel or impeller It is the main element of the pump. The impeller determines the main specifications and pump parameters. The life and use of pumps largely depends on the service life of the working wheels. For the service life of the impeller, many factors affect the most significant of them, this is the quality of the installation and operating conditions of the equipment.

Mounting quality. It seemed that there was a difficult, connected a pipe or a hose on suction and pressure pipes, filled the pump, and the suction pipe with water, turned on the plug into the socket and everything is fine. The pump began to serve water and this can be reaping the fruits of his work. So it seems at first glance, and in fact everything is much more complicated. The quality of the installation performed is very dependent on the service life, and the conditions for its operation. The most common mounted errors:

connecting a pipe of a smaller diameter than the pump inlet nozzle. This leads to the fact that the resistance in the suction line increases and, accordingly, leads to a decrease in the depth of the pump suction and its performance. Plants manufacturers pumping equipment It is recommended to increase the diameter of the suction line on one standard size at a suction depth of more than 5 meters. The truncation of the diameter of the suction pipeline also leads to the loss of pump performance. The truncated suction pipe is not able to skip the volume of the liquid that the pump can produce. If the hose is connected to the suction nozzle of the pump, then it is obligatory must be corrugated and suitable diameter; Simple hoses Connect to the suction pipe is strictly prohibited.In this case, due to the discharge created by the impeller on the absorption, the hose is compressed and the truncation of the suction line occurs. The pump will feed water at best badly, and at the worst not to serve at all;
absence check valve With a mesh on the suction line. In the absence of a check valve, after turning off the pump, water can go back to the well or well. This problem is relevant for pumps, in which the suction pipe is below the pump absorption axis, or for pumps in which the suction nozzle is under pressure, when it stops. The axis of the pump suction is the center of the suction pipe;
schedule pipes on a horizontal plot or counter bias from the pump in the suction pipeline. This problem leads to the "convulsion" of the suction pipeline and, accordingly, to the loss of pump performance or completely to the termination of its work;
a large number of turns and bends on suction. This installation also leads to an increase in resistance in the suction pipeline and, accordingly, to a decrease in the depth of suction and pump performance;
poor tightness in the suction pipeline. In this situation, air seats occurs in the pump, which affects the suction ability of the pump and its performance. The presence of air also leads to increased noise during the operation of the equipment.

Operating conditions for equipment. This factor includes the operation of equipment in cavitation mode and work without fluid duct "dry stroke"

Cavitation. In cavitation mode, the pump works with a lack of water at its input. This equipment operation mode depends entirely on the correctness of the installation performed. With a lack of water at the entrance to the pump due to the discharge of the working wheel created, the so-called "cold boiling of fluid" on the surfaces of the impeller occurs in the zone from a low pressure on the high pressure transition. In this zone, air bubbles begin to be shaved. Due to these numerous microscopic explosions in the area with more high pressure (for example, on the periphery of the impeller) microscopic explosions cause jumps of pressure that damage or may even destroy the hydraulic system. The main sign of cavitation is, increased noise when operating the pump and gradual erosion of the impeller. On (Fig. 3) can be seen, in which the brass impeller has turned in during its operation in cavitation mode.

NPSH. This characteristic determines that the minimum, additional value of the porcelain pressure at the entrance in a particular type of pump required to work without cavitation. The NPSH value depends on the type of impeller, on the type of fluid pumped, as well as on the number of engine speed. External factors, such as the temperature of the pumped liquid and atmospheric pressure, affect the value of the minimum backward.
Work without fluid duct "dry stroke". This mode of operation may occur both in the absence of a pumped fluid at the inlet to the pump and during the operation of the equipment on the closed valve or crane. When working without fluid flow, due to friction and lack of cooling, fast heating and boiling liquid in the pump working chamber occurs. Heating leads to the deformation of the pump elements (Venturi tubes, diffuser (s) and working (s) wheels (C)), and then to complete destruction. On (Fig. 4) You can see the deformation of the working wheels when operating the pumping equipment in the "dry stroke" mode

The consequences of "dry stroke"

To eliminate such situations, it is necessary to prevent such cases and establish additional protection from the operation of the equipment in the "dry stroke" mode. Some methods of protection can be found . It is also necessary to conduct a periodic inspection and maintenance of equipment to increase its life. During the inspection, it is necessary to pay attention to the supply of air (suction pipe) and the absence of leaks in connections and the end seal. This is especially true in cases where pumping equipment long term Pretty and not exploited. In case of detection of problems, they must be eliminated independently or invite a specialist from the service center, if, for example, it has been necessary to replace. Repairs in such cases will not be long and not expensive. Much more complex I. more repaired It is worth when it is necessary to change all the insides of the pump and, in addition, also rewind the stator. Repair in this case can cost approximately as much as it costs new pump. . Therefore, when detecting deviations in the equipment (reduced pressure and consumption, noise has appeared when working) It is necessary to carefully examine and inspect the entire system independently and troubleshoot. It should be added that when repairing the pumping equipment is carried out, very often when replacing the impeller, you can face such a problem, how to remove it? This is relevant for pumps in which the impeller is brass or from noril, but with a brass insert or cast-iron with a cylindrical landing for a key. During operation, such wheels "bakes" to the shaft. It also contributes to the quality of our water, with a large content of stiffness or iron salts. To remove such wheels from the shaft and at the same time nothing damaging is very hard. To remove the wheels, you should first clean them from scale and sediments of stiffness salts using the means used in the life of Santri or the like. This tool perfectly clears the inside of the pump from the sediments of stiffeners. If after cleaning the impeller is not removed, you should apply "WD" to the tool that is used when repairing vehicles or any liquid lubricant that is at hand. Due to the large fluidity, the WD fluid penetrates deep into all emptiness and pores, thereby wetting and lubricating work surfaces. Then with the help of the sleeve (the sleeve should be a diameter of hectare 3-5 mm larger than the diameter of the shaft, but not to go beyond the brass insert, it is relevant for working wheels from plastic) and the hammer try to move the impeller from its seat. You also need to pay attention to the shaft itself, so as not to damage the thread on which the nut is screwed, fixing the impeller. For this, the sleeve is put on the motor shaft and hit the hammer on it. You need to beat with such an effort so as not to damage the mechanical end seal, which is on the shaft, immediately behind the impeller. As you know, the movable part of the mechanical end seal is a spring that constantly presses the working surfaces of the movable and fixed parts of the end seal to each other. By compressing this spring, we will be able to move the impeller by 1-2 mm. on the motor shaft. Then we need to move the impeller on the shaft to the other side. For this, you will need two slotted powerful screwdrivers. Screwdrivers are inserted between the engine support (caliper) and the impeller opposite each other necessarily under the scopes (so as not to break the blades of the plastic impeller). Bringing the impeller and try to move it on the shaft in reverse side. Then take the hammer, the sleeve and do the procedure described above. Such attempts may be somewhat while the impeller does not take. In the same way, it was necessary to remove brass and cast iron working wheels. For proper montage and observance of operating conditionsworking wheel or impeller, as well as the pump itself can serve for a long time and reliably for many years.

Thanks for attention.

Pumps have long been included in our life, and the refusal of them is not possible in most industries. Exists a large number of The varieties of these devices are: each has its own characteristics, design, appointment and opportunity.

The most common - centrifugal - the aggregates are equipped with an impeller, which is the main part transmitting the energy coming from the engine. Diameter (internal and outer), shape of the blades, width of the wheel - all these data are calculated.

Types and features

Most pumps carry out their work using one or more toothed or flat wheels. The transmission of motion occurs due to the rotation of the coil or pipe, after which the liquid is issued to the heating or water supply system.

These types of working wheels of centrifugal pumps can be distinguished:

Open - Have low performance: efficiency is up to 40 percent. Of course, some landfinding shells still use such aggregates. After all, they have high resistance to clogging, while they are easy to protect them using steel overlays. The simplified repair of pumps of pumps is added to this.
Semi-closed - Used to pump or transfer fluid with low acidity and content of a small amount of abrasive in large soil units. Such elements are equipped with a disk from the opposite to suction.
Closed - Modern and most optimal type of pumps. Used for feeding or pumping waste or clean water, oil refining products. The peculiarity of this type of wheels is that they can have a different amount of blades under different angles. Such elements have the highest efficiency, this is explained by high demand. The wheels are more difficult to protect from wear and repair, but they have high strength.

To make it easier to choose and distinguish between each pump, there is a marking that allows you to correctly select an impeller for it. In many ways, the type is determined by the volume of transmitted liquids, and different engines are used.

As for the number of workers blades in the wheel, then this number ranges from two to five, six pieces are less common. Sometimes there are protrusions on the outer part of the discs of closed wheels, which can be radial or repeating the outlines of the blades.

The impeller of the pump is often produced by solid. Although, for example, in the United States, this element of a large soil unit is made welded from the cast components. Sometimes the working wheels are made with a removable hub created from soft material.

This element may have a through hole for processing.

The hole in the hub for planting on the shaft may be conical or cylindrical. The last option allows you to more accurately fix the position of the impeller. But at the same time, the surfaces need very careful processing, and it is more difficult to remove the wheel with a cylindrical landing.

With a conical landing high accuracy Processing is not required. It is only important to observe the taper, which is mainly in the borders from 1:10 to 1:20.

But there is a disadvantage of this approach in fixing: there is a significant beating of the wheel, which causes elevated wear, especially with the gland seal. In this case, the position of the wheel relative to the snail in the longitudinal direction is less accurate - another minus.

Although, of course, some designs allow you to eliminate this disadvantage by moving the shaft in the longitudinal direction.

The impeller of the water pump is connected to the shaft using the pertrite of the prismatic shape made of carbon steel.

Modern landcases increasingly use another type of fixing the impeller with the shaft - screw. Of course, there are certain difficulties in creating, but the operation is much simplified.

Such a solution is used in large ground pumps of the GR series ( domestic production), as well as in the aggregates of American and Dutch origin.

A large forces act on the impeller of the centrifugal pump - the result:

changes in pressure on the wheel zone against the hub;
changes in the flow direction inside the wheel;
pressure differences on the posterior and front disks.

If there are end-to-end holes in the hub, the axial force acts the most on the shaft shank. If the holes are no longer, the strength is directed more on the bolts, which are used to fix with the rings of the shaft.

Vortex and centrifugal vortex pumps. The wheel of the centrifugal pump is a disk with radially located blades, the number of which is within 48-50 pieces having drilled holes. The impeller can change the direction of rotation, however, it takes a change in the purpose of the nozzles.
Labire pumps. According to the principle of action, such aggregates are similar to the vortex. In this case, the impeller is manufactured as a cylinder. On internal I. external surface There are screw channels of the opposite direction. Between the hull sleeve and the wheel there is a gap in the amount of 0.3-0.4 mm. When the wheel rotates, whirlwinds are formed from the crest.

Truck wheel

The trimming wheel of the centrifugal pump allows you to reduce the diameter to reduce the pressure, while the efficiency of the pump hydraulics does not deteriorate. With a small decrease in the efficiency, the feed and pressure increase quite significantly.

The snipper is used when the pump characteristic does not meet the current conditions of operation within certain limits, and the system parameters remain unchanged, and cannot be selected by the directory unit.

The number of turnings that are created by the manufacturer does not exceed two.

The cutting size is in the range of 8-15% of the wheel diameter. And only in extreme cases, this indicator can be increased to twenty.

In turbine pumps, blades are scattered, and in spirals - more wheels and wheels. These performance, pressure, power and speed factor under the procedure are determined as follows:

G 2 \u003d g 1 d 2 / d 1;
H 2 \u003d H 1 (D 2 / D 1) 2;
N 2 \u003d N 1 (D 2 / D 1) 3;
n s2 \u003d n s1 d 1 / d 2,

where the indexes indicate the data to (1) and after (2) sharpening.

At the same time, such changes occur depending on the change in the coefficient of the wheel speed: 60-120; 120-200; 200-300:

reducing the efficiency for every ten percent of the turning: 1-1.5; 1.5-2, 2-2.5 percent;
reducing the normal diameter of the wheel: 15-20; 11-15; 7-11 percent.

Calculation of the wheel of the centrifugal pump allows you to determine the coefficient of speed in the formula:

(√Q 0 / i) / (h 0 / j) ¾.
n S. \u003d 3.65 N * (the result of the first point).

where j is the number of steps; i is a coefficient depending on the type of impeller (with a two-way fluid inlet - 2, with one-sided inlet of fluid - 1); H 0 - optimal pressure, m; Q 0 - optimal feed, m 3 / s; N is the rotational speed of the shaft, rpm.

The calculation of the impeller of the centrifugal pump is not independently recommended - the work is responsible and requires the attention of specialists.

Repair and replacement

Under the poorly made element, an uneven load is created, which provokes a violation of the equilibrium of the flowing parts. And this, in turn, leads to a rotor imbalance. If a similar problem arose, the impetence wheels are needed.

This procedure includes such actions:

Disassembly pumping part.
Expressing, changing the wheel or several wheels (depending on the design).
Check the remaining pump elements.
Assembling unit.
Testing the characteristics of the device during load.

The procedure for repairing an element can cost from 2000 rubles. You can buy a working wheel of a centrifugal pump from 500 rubles - by itself, for the smallest option.

Device in work (video)

Photo of centrifugal pump

Equipment, with the help of which pumped water, is called pumping, it is divided into several groups: bulk and dynamic. In this article we will talk about the dynamic pumps to which centrifugal aggregateAnd what is the working wheel of the centrifugal pump.

So, what is the centrifugal pump? As already mentioned earlier, this equipment with which water is pumped up.
How the design works:

This happens with centrifugal power. Simply put, inside the pump there is water, which, with the help of blades and centrifugal force, is discarded to the walls of the housing.
After that, water under the action of pressure begins to flow to the pressure and suction pipeline.

Thus, the water continuously starts swing. To better understand how this happens, it is necessary to figure out what the pump consists of.

For which the pump is used

How water pumping occurs through the pump in theory is already clear, but what parts of it help in this matter - no.
Let's talk about what parts it consists of:

The impeller of the centrifugal pump.
Pumping shaft, also an important part.
Selns.
Bearings.
Case.
Pumping machine.
Sealing rings.

Note. Centrifugal pumps are used not only for water production, and chemical fluids are also produced, therefore, composite pumps may vary depending on the method of their use.

Working wheel

One of the most important details The pump is a impeller, since it is it that creates centrifugal power, water under pressure begins to pump.
So, let's wonder what it consists of, and how it works, it consists of:

Front disk.
Rear disk.
The blades that are between them.
When the wheel starts to rotate, the water located inside the blades also begins its rotation, because of which the centrifugal force arises, the pressure appears, the water is appear to the periphery and look for the output.

Since the pumps are swing not only water, but also chemical liquids, so the impellers and the centrifugal pump housing are made from a variety of materials:

For example, bronze or cast iron is used to work with water.
To improve wear resistance when working with water, which contains mechanical impurities, you can use the impeller made of chromium cast iron.

And if the pump is designed to work with chemicals, it is necessary to use a steel impeller.

Characteristics of the impeller

Below will be the table of working wheels classifications:

Classification of the impeller of the centrifugal pump
Number of working wheels	Single-stage pump
Axis	Vertical Horizontally
Pressure	Low,< 0,2 МПа Average, 0.2 - 0.6 MPa High,\u003e 0.6 MPa
Liquid submission	unilateral bilateral open closed
Method of housing connector	horizontally vertical
Method of removal of liquid	spiral shopping
SPECIALLY	smart normal experimental
Purpose	water pipes sewerage alkali oil others
Engine connection	driving coupling
Located in relation to water	surface depth immersed

Causes of the kneading wheel

Often, the main cause of the breakdown of the impeller is cavitation, that is, the vaporization and formation of steam bubbles in the liquid, which entails the erosion of the metal, since there is a chemical aggressiveness of gas in liquid bubbles.
The main causes of cavitation is:

High, more than 60 degrees Temperature
Not dense compounds on the suction pressure.
The greater length and small diameter of the suction pressure.
Clogging suction pressure.

Council. All these factors entail a breakdown of the pump impeller, therefore, you need to carefully follow the observance of the working conditions of your equipment. After all, it is not for nothing for each type of technology, there are our operating conditions that are created for greater wear resistance.

Symptoms of the impeller

The vehicle breakdown of the centrifugal pump can not be noticeable immediately, however, there is general signsthat indicate that with your technique something is wrong:

Suction drying.
Noise.
Vibration.

Council. If you have noticed the above-described signs in your pump, it is necessary to stop its work. Since cavitation reduces the PDD of the pump, its pressure and accordingly the performance.

Moreover, it affects not only the work of the wheel, but also to other parts of its details. With long-term exposure to cavitation, the details become rough, and the only thing that will help them - is the repair or purchase of new equipment.

Repair of the impeller

If the impeller still broke, or the pump broke, it can be repaired with his own hands.

Council. But it is better to contact a specialized repair, as this requires special tools.

Nevertheless, here is a small instruction, how the working wheels of the centrifugal pump are made independently.
Disassembly:

Using the shooter, a half.
The rotor is applied to the unloading disk to the end, where suction is performed.
Mark axis shift arrow.
Disassemble bearings.
Remove the liners.
With the help of a special pull-out discharge disk.
Using squeezing screws alternately, not allowing tasks, remove the impeller from the shaft.

Repair of the impeller:

In order to repair the repair of the centrifugal pump of the centrifugal pump.
Steel:

If the wheel is worn, first, it is guided, after which it is pulled out on the lathe.
If the wheel is very worn, then it is removed, and then welded new.

Cast iron:

Cast-iron wheels, as a rule, simply change, if you can get around sharpening, then the necessary places are poured with copper, and then drag.

After the wheel is repaired or replaced, the pump is collected back:

Wipe the centrifugal pump.
Check the presence of burrs and care, if it is, they are eliminated.
The impeller is collected on the shaft.
Return a discharge disk.
Install a soft packing of the glands.
Wrap nuts.
Rolling the gland.
The rotor is supplied to the head of the discharge disk to the heel.

For greater understanding of the repair process, you can watch the video in this article.

Prices

The price of the impeller in different stores is its own, it all depends on the material of the pump itself. The initial cost of 1800 rubles, the ultimate - 49 tr. It all depends on what is your centrifugal space, for which you use it, and what size it is, as well as how many wheels in it.
Therefore, in order to avoid the cost of repair, you must carefully follow its work. And also, when there are any signs that indicate its malfunction, it is not necessary to use it until it stops work, it should be attributed to a specialist who will replace or repairs to you those details that have been breaking.

Centrifugal pump For water, as one of the types of dynamic hydraulic devices, is used in water supply, energy industry, water supply, automotive industry, heat supply and other areas when pumping any liquids, such as water, aggressive chemical reagents, acids, fuel, wastewater.

The centrifugal pump is a sealed spiral body, which is a working chamber, inside which the shaft is rigidly enshrined. The collected device is able to work only if all its cavities are filled with water before launch.

Centrifugal pumps have such basic nodes as:

housing;
suction nozzle;
discharge nozzle;
working wheel;
worker;
bearings;
selns;
guide;
casing.

Case (stator), suction and injection pipe

The centrifugal pump housing is the carrier element of the entire design, it is a steel or cast-iron bowl, inside which the impeller will be placed. The housing has two holes: suction from the bottom and ejecting the side on the edge of the case. All other details are attached to him. Most often, it can be cast, spiral shape caused by the hydrodynamic features necessary to impart fluid to the right direction during the pump operation. Case happens to how separate element Constructions with connected nozzles and cast (in this case, nozzles and housing can be a single unit). Bracket, with which the whole design is attached to any plane, is part of the housing.

IN low part The pump housing is screwed up suction (receiving) nozzle required to supply water inside the working chamber. Through this pipe, the pump is connected to the pipeline immersed in a pond or another source of fluid from which the fence will occur. Depending on the design, the suction nozzle can be both a molded part of the pump housing and separated.

On the side of the case there is a discharge (giving) nozzle that exercises water from the pump's working chamber. A pressure pipe that goes to the consumer will be connected to the discharge nozzle. The nozzle is a cast part of the case.

Impeller (rotor)

The main element committing useful work In the pump, is the impeller (impeller).

The impeller is made of cast iron, copper or steel. The rotor consists of two connected disks, between which there are blades curved against the axis of the wheel rotation from the center to the edges. The central part of the design, having a hole (neck) on one of its sides, equal to the diameter of the suction nozzle, fits tightly to its input for the immediate contact of the blades with the absorbable water. The wheel is placed inside the case of the case and completely "fills" the working chamber, which eliminates the slit flow of the liquid, leaving free space only in the disc chubs.

Most of the water during operation accumulate between the blades, which allows it when rotating the wheel sprinkle from the center to the edges under the action of the emerging centrifugal force, without a decrease in pressure. The water discarded from the center forms at the periphery high blood pressure And it is displaced through the injection nozzle outside, while the vacuum is absorbed by the liquid through the center of the disk, and therefore water pumping occurs permanently. In some models of high-performance centrifugal pumps on the shaft, several wheels are fastened. The pumps of this type are called multistage. For pumping aggressive chemicals, the impeller can be made from ceramics, rubber or other stable materials.

Wheels are several types:

closed type;
open type (where the blades are open and located on one disk);
stamped;
cast;
riveted.

Open impellers differ from the location of the blades only on one disk, without covering. These impellers are applied when low pressures And when pumping excessively dense and contaminated suspensions, which allows you to have free access to shovels for cleaning them. IN simple pumps The wheel is closed, while both disks with blades are made in the form of a monolithic part. For large, heavy pumps, the wheel is made by stamping from steel. Depending on the rotational speeds, the predetermined shape of the blades can be both direct and at an angle. For high-speed pumps, to increase productivity, the blades begin with the sleeve. On the shaft, the wheel is mounted with swords. The riveted the same impellers are used in domestic water pumps of low power.

Tree impeller

The rotational moment is transmitted to the impeller through the shaft on which the wheel is rigidly fixed.

The shaft is made of wrought steel, and for high load - from doped, with a alloy of vanadium, chromium or nickel. For working with acids shaft is made of stainless steel. The shaft itself is installed on the bearings, it is necessary to avoid distortion and vibrations of the pump during operation.

The shaft of the impeller is hardly the most susceptible to damage item. Vibrations that appear as a result of improper shaft balancing can lead to unstable work or even to the destruction of the pump. Due to the high speed of rotation, the working shafts of the unit are manufactured taking into account critical revolutions.

Work shafts are the following types:

hard;
flexible;
compounds (the pump shaft is simultaneously the engine shaft).

The hard shaft is done for quiet operating modes, when there are no high-demand operations and no speeds exceeding permissible. Flexible shafts Applied where stability is necessary with a possible frequent exceeding critical revolutions. A small disbelcing of masses during rotation is able to lead to fluctuations and cause a deflection destructive for the shaft. The shaft should be well balanced statically, and in some cases dynamically dynamically using special machines. The fusion shaft is used in domestic pumps, in this case the impeller is attached directly to the rotor of the electric motor.

The remaining components of centrifugal pumps

Bearings of the working shaft are the necessary element of the structure. Bearings for pumps are made with cast iron liners, bobbito. Lubricated with thick or liquid lubrication. In some cases, water cooling of oil is provided in the bearings. Cooling lubricant It is carried out both with the help of a water shirt and through a serpent.

In the pumps, not only roller and ball, but also rubber, textolite and other bearings can be applied. This type of water lubricant bearings.

Rear wall (casing) refers to the case. It is installed directly on the body. The sealing of the casing is carried out by laying between the wall and the pumping of the rubber gasket, which will prevent penetration into air, which can disrupt the normal operation of the design and reduce the pump performance due to the falling of the vacuum. To the engine from the working chamber did not penetrate water, on the shaft at the place of his joint with back wallThe nest put a seal (seal).

The guide apparatus is a static disk with grooves directed in the opposite direction from rotation of the rotor. The guide apparatus is necessary to reduce the velocity of water at the outlet of the wheel and partial transformation of the energy of this velocity into the pressure. In most ordinary pumps, the guide apparatus is cast from cast iron, and in specialized - from bronze or steel. For household pumps It can be made of aluminum or plastics.

The glands are made with a soft padding of asbestos cord, paper or cotton. A stuffing is impregnated with lard on graphite. From the suction side, the gland is made with a water shutter. The device of such a gland is a clutch with a sealing ring to which the fluid from the injection pipeline is supplied, preventing air from entering the operating chamber. In the chemical pumps, the shutter is carried out with a liquid, leaving outside. For pumping high-temperature liquids, the glands must have a cooled design.