Pumps according to the principle of operation. Centrifugal pumps: device, principle of operation, advantages and disadvantages

All operated pumping devices are designed to interact with the liquid and differ in the nature of the impact of functional components on water.

All pumps are divided into 2 main categories:

1. Dynamic.
2. Volumetric.

In dynamic devices, the liquid is pumped under the action of forces interacting with water in the working cavities between the inlet and outlet of the device. Centrifugal pumps are considered characteristic representatives of this category. Detailed description classification of such devices is given in this article.

Varieties of centrifugal pumps

The main functional component of each centrifugal pump is a wheel with blades, located on a special shaft in a housing in the form of a spiral. Such a pump operates due to the action of centrifugal force. The liquid enters the working body in the axial direction. When the blades rotate, the water is pressed against the walls of the housing, and then exits under pressure through the injection hole. At the point where water enters the pump, the pressure level decreases, and in the area of ​​the impeller it increases. Basic functional feature centrifugal pumps is the ability to continuously supply water.

There are such types of centrifugal pumps:

• Single stage horizontal. Design features determine the name of these cantilever mechanisms, in which the impeller is mounted on the shaft tip. In this situation, the shaft acts as a console, at a distance between the front bearing and the wheel. In this case, the pump is fixed on the foundation plate, which also holds the electric motor;
• Multistage horizontal. These devices have several impellers on one shaft. The functional characteristics of such devices are comparable to several pumps installed on one water supply. The main task of such pumps is the formation of high pressure with relatively small water supplies. Such devices create a pressure approximately corresponding to the combined indicator of the injection pressure of the water flow in the system by several devices;
• Fecal pumps are used to interact with liquids containing a large number of various impurities. The supply of the working fluid is carried out in the axial direction. In everyday life and industry, vertical and horizontal devices are used. The main distinguishing feature of such devices is the relatively small number of blades on the wheel. The body of the fecal pump is equipped with special hatches necessary for servicing the device.
• Dredgers and sand devices are used to interact with industrial effluents containing many different impurities. Such models of pumps contribute to the pumping of slurry with a normal bulk density of 3 kg/l.

Separately, one should consider centrifugal pumps to extract water from wells.

Operating principle

The channels between the blades are filled with water during the operation of a centrifugal pump. When the shaft rotates, centrifugal force acts on the water located between the blades, which contributes to the removal of liquid from under the working stage. Thus, a rarefaction can occur in the center of the stage, accompanied by an increase in the pressure index at the periphery. Water is pumped through the suction pipeline, and then through the pipe it is sent to the pump.

The working fluid moves through the pipeline, due to the difference in pressure in the central part of the wheel and the receiving container used. Water under pressure is removed from the impeller, directed to the spiral chamber, and then enters the pressure pipe, through which it flows into the pressure pipeline. The centrifugal force index increases significantly with an increase in the number of shaft revolutions, therefore, the pressure in the system increases. Centrifugal pumps can be driven by a conventional electric motor or a turbine.

To date similar devices applied in a wide variety of fields. There are many subcategories of centrifugal pumps that are in great demand in the domestic market.

Downhole centrifugal pumps

Downhole pumping devices are divided into two main subcategories:

1. Semi-submersible.
2. Submersible.

Semi-submersible units often have a multi-stage design with an installed pressure pipeline, electric motor and reliable support unit. Elastic rubber or lignofoil bearings are mounted in the equipped crosses of the used pressure pipe, thanks to which the pump shaft can rotate normally. Several sections of the shaft are combined with screwed couplings. Thanks to chrome-plated coating, the shaft walls are reliably protected from corrosion, and their wear resistance increases. The counter-reverse mechanism blocks the possible rotation of the shaft in the opposite direction. Impellers in devices are open or closed type. Mechanisms with open wheels are much less sensitive to all kinds of impurities. However, pumps with closed impellers have a significant increase in efficiency. The pressure pipeline in the semi-used devices submersible type assembled from several sections.

The motor can be serviced without special work in semi-submersible systems. However, the installation of such systems requires compliance with certain rules in the process of drilling a well, which must be vertical and straight. Also to distinctive features such equipment includes high metal consumption and installation complexity.

The submersible pump descending into the well is equipped with an electric motor and a multi-stage water intake system. The device is immersed in the installed casing pipe and fixed to the pressure pipe structure using a special coupling. Weight pumping unit is transmitted to the base plate through a pipeline consisting of several sections. It is connected to the pressure pipeline using special clamps. electrical cable powering the engine. The operating device is controlled by a remote automated system.

Compared to semi-submersible systems, submersible systems are characterized by insignificant metal consumption, their installation can be performed in non-straight boreholes, installation and dismantling are much easier. The disadvantages of such devices are high rate sensitivity to the presence of sand mass in the pumped water.

Advantages and disadvantages of centrifugal pumps

Centrifugal pumps are endowed with many advantages, due to which they are widely popular in the domestic market.

These advantages include:

• Relatively large number of shaft revolutions. This makes it possible to use electric motors and turbines as mechanisms that provide rotation;
• The possibility of gradual reduction or increase in power. Due to this quality, the start of the device can be performed with the valve at the outlet closed;
• When several pumps are installed on the same pipeline, the level of pressure and the intensity of the water supply increase significantly;
• Simplicity of design;
• Comparative cheapness;
• Possibility of using an automated control system;
• Fluid can be drawn into the pump from a great height;
• The efficiency of such devices is approximately 0.6-0.8;
• Reliability of operation.

The disadvantages of this class of pumps include:

1. The probability of unstable water supply, changing in case of unstable operation of the electrical circuit.
2. When starting up, the working tank of the centrifugal pump must be filled with water. Often, water has to be poured into the device if the liquid level does not reach the inlet pipe.
3. The functional characteristics of the mechanism can be significantly reduced in a situation where air mass enters the spiral, bearings and other components fail faster.

In order for air to be safely removed from the system, special plungers are installed on the casing.

It must be understood that the functional characteristics of the pumps are affected by several factors:

• The occurrence of blockages in the suction area. To do this, the filter is replaced;
• Exceeding the permissible temperature level of the pumped water. In this case, the pump must be turned off and wait until the liquid has cooled;
• Pipe diameter too small in relation to its length. System design flaws that need to be corrected;
• Depressurization of joints shutoff valves, as well as installed flanges. In such cases, the cause of depressurization is found and appropriate sealing measures are taken.

Self-assembly of a centrifugal pump is not difficult. You should always understand what difficulties may arise during operation. It is necessary to constantly monitor the operation of the device in order to avoid problems in the future. When the first characteristic signs of a violation of the stability of the supply of the working fluid appear, you need to independently identify the problem that has arisen. If the necessary measures are taken in a timely manner, it will be possible to use the pump longer without the need for repair work.

Every person who has his own plot has repeatedly faced such a problem as the lack of water. Water outage can be only for a few hours, and sometimes water can be absent for several days, in such cases, many people drill a well and install water pumps. Or, you can face the problem of lack of water during the irrigation season, as a rule, the water pressure at such hours is very small and, again, you cannot do without a pump.

So, by purchasing a pump, you are at times make your work easier. You will always have water for domestic needs, for drinking, as well as for watering your garden and vegetable garden. Moreover, today's market has such a large range of products, both domestic and foreign. Pumps presented different types and designed for various purposes so it won't be too hard to choose.

Consider what types of water pumps are. They fall into two broad categories: household pumps intended for installation on own site and professional- large pumps that are installed in various industries.

In this article, we will consider household pumps in more detail, since we will still talk about them. But it's worth mentioning the main difference e household pumps from industrial ones: they have a longer motor resource and with the help of such pumps, it is possible to pump large quantity cubic meters of water. These pumps are used to provide big cities water or any industrial enterprise.

• devices for water supply;
• drainage pumps;
• circulation pumps.

By working principle pumps are divided into:

• wells;
• downhole;
• self-priming;
• manual.

By collection method water pumps are:

• outdoor;
• submersible;
• injection.

Let us consider in more detail the pumps according to the method of water intake.

Outdoor pumps

External pumps are used for water intake from wells, open reservoirs, water supply systems. When the pump is running, water is sucked into the pipe one end of which is in the water. The depth from which he is able to suck up water, the height to which he can raise a column of water, as well as his productivity are completely dependent on its power. In turn, external pumps are also divided into two types: vortex and centrifugal. The former are used to extract water from small wells, but the latter can cope with pumping water from deeper wells.

Advantages outdoor pumps:

• easily pumps water to a height of 15 to 20 meters;
• the pump is easy to maintain;
• just mounted.

disadvantages outdoor pumps:

• with its help it is impossible to pump out water from a depth of more than 7-8 meters;
• the electric motor is very noisy, there is, of course, an option to purchase silent pump, but the price will be much higher.

Submersible pumps

Submersible pumps, as well as external ones, are used for water intake from wells and wells. By the name itself, you can understand that such a pump is immersed directly into the water itself so it does not need to provide dry running protection.

Advantages submersible pumps:

• with extraordinary ease, such a pump is able to lift water from great depth, will cope even with a depth of 40-50 meters;
• silent operation of the pump motor;
• does not take up much space;

One of the biggest drawbacks of submersible pumps is its high price compared to outside.

injection pumps

Injection pumps are used if there is a need pump water from deep more than 10 meters. The injection pump differs in that it has two suction pipes: one of a larger diameter and the other of a smaller one. At the ends of both pipes there is a special nozzle - an injector. Thanks to this nozzle, the pump can pump water from a greater depth.

Advantages of injection pumps:

• affordable, reliable and easy to install;
• safe;
• provide water lifting from a great depth;
• suitable for domestic use;
• have great performance;
• electricity consumption is reduced.

Water pump design

If we consider a water pump from the point of view of mechanical engineering, then it is a hydraulic machine that is designed to pumping water in the horizontal or vertical direction. In order for water to start moving in one direction or another, it must be informed of a certain kinetic energy. Based on this, a water pump can be thought of as a device that converts electrical energy into kinetic energy, due to which fluid is moving.

According to the principle of operation, pumps are divided into centrifugal and vibration.

For example, a centrifugal pump consists of such elements as:

• working chamber;
• Working wheel;
• guide apparatus;
• pump shaft;
• discharge pipe;
• pump housing;
• suction pipe.

But vibration pumps have in their design flexible membrane, which shares the working capacity. On one side of the membrane is a mechanism that sets it in motion, and on the other - area with water.

Popular Water Pump Manufacturers

One of the popular manufacturers of water pumps is the Italian company Calpeda. She is considered recognized leader on the world market pumping equipment. The pumps produced by this company are considered the most reliable in the world. They are manufactured using high-precision equipment, highly qualified personnel work in the production and, moreover, the company is famous for good technical tradition. Absolutely all materials and spare parts for Calpeda pumps are made in Italy.

In addition to this recognizable brand, there are also such as Gardena or Makita, which are also quite recognizable brands. Are stable and reliable companies that today are only increasing their potential.

The cost of water pumps their comparison

Prices for water pumps can be completely different, the price depends on:

• engine power;
• pump type;
• manufacturer's marks.

Therefore, before buying a particular pump, you should first decide what type of pump you need, you also need know its power, and then consider pumps from different manufacturers.

For example, a 900 W Gardena submersible water pump with a maximum capacity of 5500 l / h will cost within 8 thousand rubles. A pump of the same brand with only a power of 500 W will already cost within 4 thousand rubles.

If we consider surface-type pumps, they go more in terms of power, respectively, and their price is higher. For example, a pump of the same brand of surface type with a power consumption of 1000 W costs in the area 15,000 - 17,000 rubles. At the same time, the price may be overestimated if the pump has some features, for example, automatic control of the water level.

Makita brand surface type pump 710 - 750 W costs almost the same as Gardena, while it has less power but has a low noise level.

Based on the foregoing, when buying a pump, first of all it is worth determine its type. You need to know where you will pump water from, after which you can already make a choice regarding one or another type of pump. It is also worth knowing what water volume will pump out the pump. And then choose the brand of the manufacturer and compare prices for them.

A pump is a hydraulic device designed for suction, pressure movement or injection of liquid by imparting external kinetic or potential energy to it.

Types of water pumps are distinguished according to their technical parameters, which include:

• the amount of fluid that the pump moves per unit of time;
• developed pressure or maximum head;
• power.

Invention history

The first types of pumps appeared in the 1st century BC. e. They helped put out fires. However, until the 18th century. such devices were rarely used.

Everything changed after the invention steam engine and increasing demand for water. Various types of pumps began to displace water-lifting devices and are widely used in economic activity person. Over time, the requirements for hydraulic mechanisms have become more and more diverse. With the development of technical thought, the main types of pumps have also been outlined. These included piston, rotational, as well as machines that do not have moving working bodies.

Advances in science and technology have led to the fact that today there are many various kinds pumps. What they are, what is their main purpose, we will consider in this article.

Household and industrial hydraulic machines

The types of pumps that exist today have a different classification. One of them concerns the scope of such devices and singles out household and industrial ones from them. The first of these machines are used for sewerage, heating and water supply in residential and industrial premises.

Industrial pumps are intended for use in various systems and settings. They are used to supply water, pump oil products and aggressive substances, as well as to carry out many other specific actions.

Positive displacement pumps

Another classification of hydraulic machines takes into account their design features and operating principle. What types of pumps are the main ones in this case? These are volumetric and dynamic hydraulic machines.

In the first of them, the working body is the camera. Under the action of the emerging pressure forces, it changes in volume, which leads to the forced displacement of the substance.

All volumetric pumps (we are considering types) are designed to supply viscous liquids. The principle of operation of such devices is based on the conversion of energy. It is transferred from the engine to the pumped liquid.

Positive displacement pumps are high pressure. In the process of their work, significant vibration arises, to dampen which the device is placed on a massive foundation. However, the advantage of these pumps lies not only in their high power. Such devices are capable of dry suction.

Types of positive displacement pumps

There are various devices in which the working body is a chamber. Among them are the following units:

1. Rotary. These are pumps that have a fixed casing that contains blades, vanes and other similar parts. The movement of the fluid in this case is facilitated by the movement of the rotors.
2. gear. This is the simplest type of positive displacement pump. These devices move the fluid in the process of changing the volumes of the cavities of the gears linked to each other.
3. impeller. If you look at such a pump disassembled, you can see the impeller, the blades of which are made of elastic material. It is located inside the eccentric body. What happens during the operation of such a device? The blades bend and, rotating, displace the liquid.
4. Cam. In these pumps, two independent rotors rotate, which contributes to the movement of fluid through the working chamber. Cam gears are widely used in the manufacture of dairy products, beverages, jams, etc. And all this is due to their ability to pump liquids with large inclusions. Also, this type of pumps is used in the pharmaceutical industry.
5. Peristaltic. In these pumps, the main working part is a multilayer flexible hose made of elastomer. When the engine is turned on in such a device, the shaft with rollers begins to rotate. They pinch the sleeve, facilitating the movement of the fluid inside it.
6. screw. A stator made of elastomer is inserted into the casing of these pumps. It contains a metal rotor having a helical shape. How will the liquid be pumped in this case? After turning on the motor, the rotor begins to rotate, changing the volume of the internal cavities. This is where the fluid moves.

Dynamic pumps

These devices are characterized by double energy conversion. Initially, it is transferred to the liquid in kinetic form. In this case, the flow moving inside the pump increases its speed. Then there is a partial transformation of the energy of the liquid into a static form. In this case, the flow rate decreases with increasing pressure. Such devices, unlike volumetric ones, are not capable of producing dry suction.

Centrifugal hydraulic machines

Consider the types of pumps The most common of them are centrifugal devices. These pumps are used to supply hot or cold water, as well as for pumping aggressive and viscous liquids, Wastewater and mixtures of water with slag, with soil, peat, etc.

How does a centrifugal pump work? Being between the blades of a rotating impeller, liquid particles receive kinetic energy from it. This creates a centrifugal force. It moves the fluid further into the motor housing. This work occurs continuously due to the pressure that ensures a constant supply of new fluid particles to the pump.

According to their purpose, centrifugal pumps are classified into:

• used in the operation of operational equipment of thermal power plants;
• for various technical purposes.

What are the types of centrifugal pumps belonging to the first group? Devices used for water circulation are divided into circulation and recirculation. Pumps installed for heat transfer are divided into boiler and network pumps. In the preparation of drinking water, condensate centrifugal pumps are used, and in the feed system for servomotors of steam turbines, pressure pumps are used.

What devices are used for various technical purposes? These are such types of centrifugal pumps as household, fire, drainage, etc.

Recently, new developments of such devices have appeared. Among them, sand centrifugal pumps are especially popular. They are used for pumping hydraulic mixtures. That is why such pumps are installed in places where there is sand in the water, as well as all kinds of industrial solids.

Vortex hydraulic devices

These dynamic pumps are similar in their characteristics to centrifugal ones, but, unlike them, they have a smaller mass and dimensions. Among the shortcomings of vortex pumps, low efficiency can be distinguished, which in the operating mode does not exceed fifteen percent. In addition, such mechanisms are not capable of pumping liquid containing abrasive particles, as this leads to rapid wear of internal parts.

Jet hydraulic devices

These pumps, unlike many other similar machines, are not able to create excess pressure at the outlet. Their principle of operation is reduced to the transformation of the potential energy of the liquid into kinetic. At the same time, there are no moving parts in jet pumps. The main working mechanism in devices of this type is a jet of liquid or gas.

Such pumps can be water-jet (for example, hydraulic elevators). In them, the working fluid transfers its kinetic energy to the pumped substance. Among the jet pumps there are also airlifts. In them, a compressor is supplied. Further, the water-air mixture is set in motion by air bubbles.

Water pumps

These devices are of many types. But mostly experts classify them according to their purpose. So, there are the following types of pumps for water:

• circulation used for forced movement of fluid in air conditioning, hot water and heating systems;
• water-lifting necessary to extract fluid from wells and wells, which are submersible and surface;
• drainage used for pumping water from wells, sewers and basements.

Types of surface-type water pumps are divided by specialists into those used for:

• pressure increase;
• cold water supply;
• fire extinguishing systems.

When choosing pumps, types, characteristics and other parameters of devices must be taken into account depending on their purpose. So, sometimes the machine will have to work in autonomous conditions. And in some cases, it will be provided with access to the electrical network.

That is why there are such types of water pumps that run on internal combustion engines. They are called motor pumps. At the same time, they are divided into gasoline and diesel. There are also electric pumps. Their work is completely dependent on the voltage in the network.

However, the main classification of pumps concerns the definition of the place they occupy relative to the source of supply. According to this parameter, they are divided into surface and submersible. Let's take a closer look at these types of devices.

Surface pumps

These devices are widely used in cottages, dachas and in country houses. They are used to increase the pressure in the water supply network, as well as for watering and irrigation. land plot. With their help, water is raised from wells, wells and open reservoirs located at a distance of up to eight meters from the axis of the pump.

There are many types of such devices. For example, according to the method of pumping water and the internal structure, they are classified into vortex and barrel, drainage and circulation, as well as cantilever (centrifugal). The last two types are most popular with summer residents. These units are easy to operate, compact and economical, and when connected to special system automation turns out full-fledged stations.

Surface pumps consist of the following main components:

1. Hose. This is a kind of aquifer from the place where the liquid is directly taken to the pump itself and further to the points of intersection with plumbing system or to water supply.
2. Ejector. This is a special device designed to improve circulation and pressure in the pump by increasing the suction depth.
3. Frame. It is most often made of composite materials, cast iron, aluminum or stainless steel. When the unit is running for all year round, in winter time the body needs protection from the cold.
4. Engine. It can be internal combustion or electric. It all depends on the type of pump.

Circulation pumps

This type of surface aggregates is distinguished by a complex device. They are usually used in autonomous heating systems in order to force the movement of water in a closed circuit and maintain a constant temperature in it.

According to their design, they have a body with a steel or ceramic rotor built into it, as well as a shaft with blades.

To date, there are the following types of circulation pumps:

• with a "wet" rotor;
• with a "dry" rotor.

The first of them are practically silent, economical, cheap and easy to operate. Their working element is designed in such a way that it is in water, which lubricates all parts and at the same time cools the engine. But such units have a significant drawback. The fact is that when the fluid circulation stops, the engine can overheat. In addition, the efficiency of such units is at an extremely low level.

All types of thermal type with a "dry" rotor have a built-in fan. Their engine is structurally isolated from the incoming fluid. In this case, all moving parts are lubricated with oil.

In turn, such pumps are divided into:

• console, in which the engine is located separately from the body;
• monoblock, where the body and the engine are also separated, but at the same time they are in the same block;
• inline pumps, which differ from the previous two in their increased tightness.

Submersible pumps

Such units are indispensable in cases where water layers lie at a depth exceeding 8 m. Submersible pumps are lowered into the well along with pressure pipe. Further, under pressure created by a hydraulic device, water enters the house.

All types of submersible pumps are highly efficient, in addition, they have efficient and high-quality cooling. According to their internal structure, submersible pumps are classified into:

• centrifugal, in which water rotates along with the blades of the impeller and is supplied outside under high pressure;
• vibrating, in which the liquid is absorbed due to the vibration and electromagnetic mechanism.

Such pumps consist of a housing, a motor and a switch. In drainage and sewage pumps, a grinder or cutting mechanism is additionally installed, designed to prevent being in the liquid solids that are larger than 5 cm.

Hydraulic fire fighting equipment

Special requirements are imposed on pumps used to localize fires. From their constructive perfection and technical parameters largely depends on the success of the fight against fire.

What are the types of fire pumps? It all depends on the extinguishing conditions. So, centrifugal-type units are installed on fire trucks. They supply fire extinguishing agents without any pulsations, do not increase pressure when the fire hose is broken or clogged, they are simple and reliable in operation.

It is also important that the centrifugal pumps installed on fire trucks do not need a complex engine drive and have a relatively low weight and dimensions. However, these units also have a number of disadvantages. They are not capable of sucking up liquid on their own and are ready for operation only after the suction line is filled with water.

What other types of fire pumps are there? These are accessory units. They are also installed on fire trucks. Auxiliary pumps make it possible to fill the housing of the centrifugal mechanism and the cavity of the suction hose with water. That is why their work is short-lived. After starting the centrifugal pump, they turn off. As auxiliary devices, rotary-type units, etc. are used.

Oil pumps

These devices are designed to reduce the friction forces that occur between moving parts of the engine. All types of oil pumps are divided into two types. The first one is adjustable. In such pumps, a constant pressure is maintained by changing the performance. The second type of oil pumps is unregulated. They also maintain a constant pressure, but only with the help of a pressure reducing valve. Most modern engines are equipped with unregulated type pumps.

Units for pumping oil are classified according to their design. They are:

• gear, with the driving and driven gears placed in the housing;
• rotary.

In the first of these two types of devices, the oil enters the housing, where it is captured by the gears. Then, through the discharge valve, it moves into the system.

The performance of such a pump is directly dependent on the frequency with which the crankshaft rotates. After the pressure of the oil injected into the unit exceeds a certain limit, it enters into operation. It passes a certain portion of oil to the suction vane or to the engine crankcase.

As for rotary pumps, they can be either with unregulated or with adjustable control. The first type of such units has a driving and driven rotors, which are placed in its housing. These parts serve to capture the oil entering the system. Further, as in a gear pump, a pressure reducing valve opens to move the substance.

With adjustable control, they provide a constant working pressure that does not depend on the speed of their crankshaft. To implement this function, they are provided with an adjusting spring and a movable stator. A constant working pressure is created by changing the volume of the cavity that is located between the driving and driven rotors.

fuel pumps

These units are the main elements without which the operation of any internal combustion engine is impossible. Their main purpose is to deliver gasoline or diesel from the tank to the combustion chamber.

One or two fuel pumps are a must for every car. These units perform work, the principle of which largely depends on the features of their design. What are the types of fuel pumps? There are two main ones. This is:

1. Mechanical fuel pump. This device is part of a carbureted engine. Its design is classic. piston pump. The main parts of such a unit are a body divided into two parts by a diaphragm, as well as two valves for supplying and receiving fuel.
2. Electric pump. This type of unit finds its application in gasoline engines with separate injection. Electric pumps are installed either directly in the tank, or in any place of the fuel line. The most widely used submersible fuel units. They are placed at the bottom of the tank. In turn, according to the type of oil injection, electric pumps are divided into centrifugal, gear and rotary.

There are many types of pumps, and all such devices are widely used in one area or another.

Centrifugal pumps are the most widely used pumps in the world. Due to its design and stable operation, this type of pumps has found wide application both for solving household problems and for basic technological processes in the most various industries industry. This article will give a complete description of centrifugal pumps, describe how a centrifugal pump works, its classification and main areas of use.

The main element of a centrifugal pump is an impeller (impeller) located inside a spiral casing (snail), which has blades directed in the opposite direction relative to the rotation of the wheel itself. The impeller is mounted on a shaft that is connected to the pump drive. When the unit is started, the impeller begins to rotate, and the liquid enters through the suction pipe along the axis of rotation of the wheel.

Under the action of centrifugal force, the liquid moves through the channels between the blades in the radial direction (from the center of the impeller to its periphery) into the spiral chamber of the pump casing, and then into the pump discharge pipe. On the periphery of the impeller is a zone of high pressure. In the center, the pressure is reduced, which ensures a constant supply of fluid to the pump.

Design of centrifugal pumps

The centrifugal pump consists of the following main parts:

• suction pipe
• Discharge pipe
• Volute casing (wet end of the pump)
• Impeller (impeller)
• Shaft seal
• crankcase pump

Classification of centrifugal pumps

Centrifugal pumps can be classified according to the design of its main elements, according to the type of installation and purpose.

According to the location of the nozzles of the pumps

• In-line pump. At of this type pump suction and discharge pipe are in line opposite each other. The pumped liquid passes through the pump. The pump is installed on straight sections of the pipeline.

• • Console pumps. The liquid enters the center of the impeller (impeller). Branch pipes are located at 90˚С relative to each other.
  
  

  By number of pump stages

  
  
  • A multistage pump has more than one impeller connected in series on the shaft. This type of pump is used to provide high head with relatively low flow. High head is created due to the sum of the pressures created by each individual wheel. The pumped liquid passes sequentially from one stage to another.
• 
  

  Shaft seal type

  Various sealing systems are used to protect against the ingress of the pumped liquid into the environment and into the mechanical part of the centrifugal pump. According to the type of system used, pumps can be divided into:

  • Centrifugal Pumps with Stuffing Box Seal (Link to Stuffing Box Seal)
  • Centrifugal pumps with mechanical seal (single or double) (link to mechanical seal)
  • Magnetic Drive Centrifugal Pumps (Link to Magnetic Drive)
  • Glandless centrifugal pumps (link to wet rotor)
  • Centrifugal pumps with dynamic seal (link to dynamic seal)

  By type of connection to the electric motor

  Centrifugal pumps are also divided according to the type of connection between the hydraulic part of the pump and the electric motor. Allocate types:

  • Coupling pump. A flexible coupling is an element that allows you to connect the motor shaft and the shaft on which the impeller is mounted. For this, both a conventional coupling and a coupling with an intermediate element are used. The use of an intermediate element makes it possible not to disconnect the electric motor when servicing the pump, for example when replacing the mechanical seal.
    
  • Monoblock pump. For this type of pumps, the impeller is mounted either directly on the elongated motor shaft, or a fixed permanent blind coupling is used to connect the motor shaft and the pump.

    By appointment

    Due to its design possibilities, the purpose of a centrifugal pump can be very different. According to this indicator, the following types of centrifugal pumps are distinguished:

    • Drainage
    • Downhole
    • Fecal
    • Slurry
    • food
    • Sanitary
    • Firefighters
    • Self-priming

    Material version of centrifugal pumps

    Centrifugal pumps are used in almost all industries, pumping a wide variety of liquids, from water to highly aggressive and abrasive slurries.

    Therefore, the choice of materials for the main elements of centrifugal pumps is very wide and is most often based on durability. this material to the properties of the pumped liquid (link to the table of chemical resistance) and the operating conditions of the pump itself.

    The following main materials can be distinguished:

    Metal version

    • Cast iron
    • Bronze
    • Carbon steel
    • Stainless steel
    • Duplex
    • Super Duplex
    • Titanium
    • Etc

    Lined and plastic versions

    When working with highly aggressive liquids, such as acids, the metal version may not always provide the necessary corrosion protection. Or the use of ultra-resistant alloys can lead to a significant increase in the cost of the entire structure.

    Therefore, the use of a wide variety of plastics as the main material in contact with the medium in centrifugal pumps has become widespread.

    Two main types can be distinguished:

    • Lined pumps. Lining is the process of applying a plastic coating to metal body pump. All elements in contact with the pumped medium are covered with a polymer layer, which significantly increases the corrosion resistance of the entire flow path. Modern technologies provide excellent adhesion between the coating and the body, because during casting, the polymer fills all the cavities and gaps.

    

    • Plastic centrifugal pumps. The main elements of the pump in contact with the medium are made of solid plastic processed on special machines.

    Materials for lined and plastic pumps:

    • PP - polypropylene
    • PVDF - polyvinyldenefluoride
    • PE - polyethylene
    • PVC - polyvinyl chloride
    • PFA - perfluoroalkoxy
    • PTFE - polytetrafluoroethylene
    • ETFE - ethylene tetrafluoroethylene (Tefzel)
    • FEP - fluoroethylene propylene

    O-ring materials

    The following elastomers are most often used as sealing rings in centrifugal pumps:

    • EPDM - Ethylene propylene rubber
    • NBR - Nitrile Butadiene Rubber
    • FPM/FKM/Viton - Fluoroelastomer
    • FFKM — Perfluorinated rubber

    Advantages and disadvantages of centrifugal pumps

    Advantages:

    • Simple design
    • Few moving parts long term services
    • High efficiency
    • High performance
    • Constant feed, no pulsations
    • Capacity control via throttle valve in the discharge line or frequency converter

    disadvantages

    • The impossibility of "self-priming"
    • Great risk of cavitation
    • Performance is highly dependent on pressure.
    • Most effective at only one given operating point. Efficiency decreases when supply is controlled by a frequency converter
    • Cannot handle multi-phase fluids containing air or gas
    • When pumping abrasive liquids, rapid wear of the main elements is possible due to high speed rotation of the impeller (about 1500 rpm).
    • Cannot handle highly viscous liquids (max. 150 cSt)

    Areas of use

    Centrifugal pumps are used in almost all industries.

    The main ones are:

    Water supply and sanitation

    Water treatment facilities

    Energy

    Oil and gas industry

    Chemical industry

    Pulp and paper industry

    mining industry

    Pharmaceutical

Main manufacturers

The major players in the centrifugal pump market can also be broken down by the industries in which they are strongest:

Water supply, sewerage, water treatment

• Grundfos: grundfos.com
• Wilo:wilo.com
• Xylem group of companies. Pumps Lowara, Goulds, Flygt, Vogel, etc.: http://xylem.ru
• KSB: https://www.ksb.com/ksb-ru/
• Pentair: www.pentair.com
• Ebara: http://www.ebaraeurope.ru/
• Caprari: www.caprari.it

petrochemical industry

• Flowserve www.flowserve.com
• ITT www.itt.com/
• Sulzerwww.sulzer.com
• Hermetic Pumpen www.hermetic-pumpen.com
• Kirloskar pumps www.kirloskarpumps.com/
• www.ruhrpumpen.com

Chemical industry

• munsch-munsch.de/
• Pompe Travaini www.pompetravaini.it/
• someflu pump www.someflu.com/
• Rutschi Gruppe www.grupperutschi.com

mining industry

• Warman. Weir mineral group https://www.global.weir/brands/
• Krebs. flsSmidt Group http://www.flsmidth.com/en-US/Krebs
• Habermann pumpen www.aurumpumpen.de/en/

A pump is a machine for creating a flow of a liquid medium. By liquid medium is meant a dropping liquid, which may contain a solid or gas phase. The purpose of the pump can be defined as follows: to impart mechanical energy to the dropping liquid in order to ensure its movement through pipelines (channels) or to transfer energy through the liquid to drive various devices and mechanisms.

Pumps are one of the most common types of hydraulic machines. They are varied design which sometimes makes it difficult to classify them. The flow of the liquid medium in the pump is created as a result of force action on the liquid in the flow chamber or in the working chamber of the pump. According to the type of working chamber and its communication with the inlet and outlet of the pump, pumps are distinguished dynamic and voluminous.

The classification of pumps can be performed according to various classification criteria:

for dynamic pumps:
according to the type of forces acting on the liquid;
in the direction of movement of the liquid medium;
by type of withdrawal;
according to the design of the impeller, etc.

for positive displacement pumps:
by the nature of the movement of the working bodies;
by the nature of the movement of the driving link of the pump;
in the direction of fluid movement;
by type of working bodies;
by the type of transfer of movement to the working bodies, etc.

A dynamic pump is a pump in which the liquid medium moves under the influence of force on it in a chamber that is constantly in communication with the inlet and outlet of the pump.
Dynamic pumps include:
1) bladed - centrifugal and axial;
2) electromagnetic - conduction and induction;
3) friction - vortex, jet, screw, vibration, etc.

The figure shows the circuit centrifugal pump. The flow of the liquid medium enters the suction pipe 1 in the axial direction, changes the direction of movement in the channels of the impeller 2 to the radial one. Under the force of the blades, the fluid flow increases the speed of the fluid and the pressure in the impeller. After passing through the impeller, the liquid enters the outlet 3. The inlet and outlet of the pump are constantly communicating with each other.

Rice. Scheme of a centrifugal pump: 1 - supply; 2 - impeller; 3 - branch; 4 - body

A volumetric pump is a pump in which the liquid medium moves by periodically changing the volume of the chamber occupied by it, which alternately communicates with the inlet and outlet of the pump.
Positive displacement pumps include:
1) reciprocating - piston, plunger, diaphragm;
2) vaned;
3) rotary - rotary-rotary, rotary-translational, rotary-rotary, etc.

The figure shows one of typical schemes volumetric pump - gear pump. The pump consists of two gears in mesh. The gears are in the pump housing with small clearances. One of the gears is driving, the other is driven. When the gears rotate, the volume of liquid enters between the teeth of the gears, is isolated from the suction and pressure lines, and then is forced out by the teeth into the pressure line.

Rice. Gear pump diagram

Further classification according to common features dynamic and positive displacement pumps can be performed:
in the direction of the axis of rotation or movement of the working bodies: horizontal pump, vertical pump;
according to the location of the working bodies: cantilever pump, monoblock pump;
according to the design of supports: with outriggers, with internal supports;
according to the location of the liquid inlet to the pump: with an axial inlet, with a side inlet;
by the number of steps: single-stage, two-stage, multi-stage;
by the number of threads: single-threaded, multi-threaded;
according to the design and type of the body connector: sectional, with an end connector, with an axial connector, double-case, with a protective case;
according to the location of the pump: submersible, borehole, with a transmission shaft;
according to the requirements of operation: adjustable, unregulated, dosing manual, reversible, reversible;
according to the suction conditions: self-priming, with an upstream stage, with an upstream impeller;
for interaction with environment: sealed, explosion-proof, low noise, low magnetic;
according to the need to maintain the temperature of the medium: heated, cooled;
at the place of installation: stationary, mobile, built-in;
by size: small, medium, large;
by power: micro, small, small, medium, large.

The current practice of classifying pumps differs from the above.
Pumps are named, for example, according to the branch of technology in which they are used: heat power pump, ship pump, nuclear industry pump, chemical pump, etc.;
or according to the type of pumped liquid: for clean water, oil, petroleum, gasoline;
for the intended purpose: nutritional, mixing, dosing, etc.