Centrifugal cantilever single-stage acid pump TsKN. Vertical pumps: types, design, features of application and maintenance. Features of sewage pumps

Vertical pumps, the design feature of which is the arrangement of the shaft and impeller corresponding to their name, are widely used both in everyday life and in various industries. Thanks to the vertical arrangement of the shaft, impeller and casing, the installation of this equipment does not require much space, which is one of the main reasons for its high popularity. Depending on the model, the vertical pump can be used as a stand-alone pump mobile device, as well as an element of the water supply or sewerage system.

Parameters and varieties

Pumps with a vertical shaft and impeller arrangement, belonging to centrifugal type devices, are classified according to the following characteristics:

1. pressure (depending on the value of this parameter, vertical pumps can be with low, medium or high pressure levels);
2. operating speed (based on this characteristic, normal, low-speed or high-speed hydraulic machines are distinguished);
3. volume of working medium pumped per unit of time (device performance);
4. the number of steps, which can be sections or rings of equipment;
5. the number of lines through which the pumped medium enters the device (one- or two-way devices);
6. the type of liquid medium for which the pump is intended to pump (drainage, fecal, chemical, water, etc. electric pumps);
7. the location of the device relative to the medium it pumps (ground models, submersible and vertical semi-submersible pumps);
8. method of connection with the drive electric motor (direct drive, gear and pulley hydraulic machines).

Vertical pumps are successfully used for pumping clean, contaminated and chemically aggressive liquid media characterized by a low degree of viscosity. The most significant advantages of hydraulic machines of this type should include:

• compactness;
• ease of use and maintenance;
• high efficiency;
• Not high level noise created during operation.

Due to the above advantages, vertical multistage centrifugal pumps (as well as single-stage ones) are actively used to equip the following systems:

• autonomous water supply;
• heating;
• drainage and purification of liquid media;
• condensation;
• filtration, irrigation and reclamation.

A vertical centrifugal pump, which raises the fluid it pumps to a higher level by increasing the pressure of its flow, can fall into one of the following categories:

• hydraulic machine of surface or ground type;
• semi-submersible pump;
• submersible type device.

Both surface models and semi-submersible and submersible pumps are equipped with an electric motor, which ensures the rotation of the impellers of such devices.

Surface pumps of the vertical type, as their name implies, are installed on the surface of the earth, in close proximity to the reservoir from which the liquid must be pumped out. The place for installing such equipment can be a pit or a specially prepared area that does not come into contact with the surface of the pumped liquid medium. A semi-submersible vertical pump, as also follows from its name, is only partially lowered into the pumped liquid medium, while the drive motor remains above the surface of the liquid.

During operation, the housing of submersible pumps is completely located in the thickness of the pumped liquid medium. If a vertical semi-submersible pump cannot be installed in wells whose shafts are characterized by a curved shape, then a submersible type device has this capability.

It should be borne in mind that vertical type electric pumps cannot be started until the inside of their housing is filled with liquid. If this requirement is neglected, the pump will run at idle speed, which can lead to overheating and, accordingly, premature failure.

Multistage centrifugal pumps of the vertical type are distinguished by higher power, which are able to significantly increase the pressure of the flow of the pumped liquid medium, which cannot be said about single-stage models. At the same time, power and efficiency multistage pumps vertical type, the higher the more sections there are in the design of such devices. Each of the sections connected to each other in series contributes to an increase in the kinetic energy of the flow of the pumped liquid medium.

Operating principle

The main design element of a vertical type centrifugal pump is Working wheel equipped with blades. In vertical multistage pumps, there are several such wheels mounted on the shaft, which makes it possible to increase the efficiency of using this equipment. The impellers of these centrifugal electric pumps are two disks mounted on a vertical shaft, which are located at a certain distance from each other and are connected by blades that bend in the direction opposite to the direction of rotation of the wheel itself.

The principle by which a vertical centrifugal pump operates is as follows:

1. When the wheel rotates in a temporary working chamber formed by two nearby blades, a vacuum of air is created, which facilitates the absorption of liquid into it through the inlet pipe.
2. After the liquid enters the temporary working chamber and begins to rotate along with the blades moving it, a centrifugal force begins to act on it, pressing it against the walls of the inner chamber.
3. When liquid enters the area of ​​the outlet pipe, already under pressure due to the centrifugal forces acting on it, it is pushed into the pressure line.

When the impeller of a centrifugal electric pump with blades attached to it rotates, the suction of the pumped liquid and its expulsion into the pressure line occurs in a continuous mode. Thus, during one rotation of the wheel, several cycles of suction and expulsion of the pumped liquid occur.

The electric pump shaft, on which its impeller is mounted, is placed in bearing units to ensure ease and accuracy of rotation, and gland-type sealing elements are installed between the moving and stationary parts of the device.

Certain models of vertical submersible pumps can even be installed in pipelines of the appropriate diameter, which can significantly increase the efficiency of pumping liquid media. The suction and pressure pipes of such models are located on the same axis.

Multistage vertical pumps

In multistage centrifugal vertical pumps, the pumped liquid sequentially passes through all sections of the device before entering the pressure pipe, which makes it possible to significantly increase the pressure of the working medium at the outlet. Depending on the model, pumps of this type may contain in their design different quantity impellers (from 2 to 10), which are fixed on one shaft, but each are located in separate modules.

The modules of a multistage vertical pump are placed in one casing, which is installed between the suction and pressure chambers of the device. All elements of the body of a multistage electric pump, the pipes of which are located in the same horizontal plane, are tightened with pins, and the joints between them are sealed using sealing elements.

As mentioned above, multistage centrifugal pumps, due to their design features, can significantly increase the pressure of the pumped liquid medium at the outlet. The pressure of the fluid flow created by a multistage pump is the sum of the pressure values ​​generated by each of its stages.

Rules for selection and service

Significantly extending the service life of centrifugal pumps, as well as ensuring their trouble-free operation, is possible by following simple rules for their use and Maintenance. To minimize the impact external factors that can damage centrifugal pumps, such installations should be retrofitted nearby additional elements. Such elements, in particular, are:

• mesh filter and valves that will protect the pump from getting into it inner part solid inclusions contained in the pumped liquid medium;
• check valve, preventing the pumped liquid from escaping back into the well, that is, preventing the pump from running idle and, accordingly, overheating of the device and its failure;
• a pressure gauge installed on the pipe through which the liquid medium is sucked in by the pump (the presence of a pressure gauge will make it possible to control the liquid pressure in the inlet pipe and thereby prevent the occurrence of cavitation processes);
• a pressure gauge designed to monitor the pressure level inside the pump itself (the presence of such a device will prevent the occurrence of water hammer).

The efficiency of the pipeline system served by a centrifugal pump is largely determined by how correctly such a device is selected. Choosing both land-based and submersible and semi-submersible vertical pumping devices, you should focus on the following parameters:

• power consumed by the drive motor;
• performance;
• the pressure of the water jet that the pump is able to create;
• body dimensions;
• materials for manufacturing parts that will come into contact with the pumped medium.

Centrifugal pumps are actively used both in everyday life and in industry. Depending on the design, they are classified as multi-stage or single-stage pumps. Pumping equipment belonging to each of these categories not only has a special internal organization, but also differs in specific technical characteristics and, accordingly, areas of application.

Design differences

A centrifugal pump, as is clear from its name, is a device that pumps liquid media due to the centrifugal force acting on them. The main working body pumping equipment This type, which ensures the formation of such force, is a wheel (or drum), on the outer cylindrical surface of which special blades are fixed.

The pump housing of this type can be made of cast iron or steel alloy. Inside such a housing there is a drive electric motor and a rotation shaft connected to it, on which the wheel with blades is fixed. According to its design, the pump impeller can be open or closed. Open impellers consist of one disk, on the outer surface of which blades are fixed, closed impellers consist of two disks connected to each other by working blades.

The blades are located at a certain angle, their bend is directed in the direction opposite to the direction of rotation of the impeller. This arrangement of the blades provides more efficient work pumping equipment. The suction of the pumped liquid medium into the internal chamber of the pump, as well as its expulsion into the pressure line, is carried out through the nozzles.

The principle by which both single-stage devices and multi-stage pumps operate is as follows.

• The liquid, located in the inner part of the pump before it starts, is captured by the blades when the impeller rotates and begins to move with them.
• Under the influence of centrifugal force, the liquid is thrown towards the walls of the inner chamber, due to which high pressure is created near them.
• When moving through the pressure pipe area, the liquid under high pressure, is pushed into it.
• When the liquid pumped by the pump is thrown towards the walls of the working chamber, a vacuum of air is created in the central part of the latter, which facilitates the suction of the liquid medium through the inlet pipe.

Due to the above-described principle of operation in pumps of both single-stage and multi-stage types, the continuity of the process of suction and expulsion of the pumped liquid is ensured when the impeller rotates. The scope of application of this type of pumping equipment is significantly expanded by the fact that, unlike piston devices, it does not create pulsations of liquid pressure in the pipeline system it serves.

As mentioned above, single-stage and multi-stage centrifugal pumps have design features that determine the differences in their technical characteristics. Thus, the main design elements of a single-stage pump are:

1. the body, which is often called the “snail”;
2. impeller with blades;
3. shaft sealing elements;
4. a shaft connected to the drive motor and providing rotation of the impeller;
5. chamber sealing elements with oil bath;
6. support for bearing assembly;
7. load-bearing support;
8. hole through which the oil level in the chamber is controlled.

A single-stage centrifugal pump, unlike multi-stage models, is equipped with one impeller. A centrifugal multistage pump can be equipped with two or more impellers with blades, which can significantly increase the efficiency of such equipment.

Due to the presence of several impellers, centrifugal multistage devices, when compared with single-stage ones, have certain advantages.

• Using multistage pumps, it is possible to pump liquid with a higher productivity, which characterizes the amount of liquid medium that the hydraulic machine passes through itself per unit of time.
• Multistage pumps are capable of generating a fluid flow with higher pressure levels, measured in meters of water column. In fact, the liquid pressure created by multistage electric pumps is the sum of the pressures created by each of its stages. This quality of multi-stage hydraulic machines makes it possible to achieve higher fluid pressure in the areas they serve. pipeline systems and move it along them to longer distances and greater heights.

A multistage centrifugal pump, depending on its design, can be sectional or spiral. In sectional type devices, during the pumping process, the liquid medium moves sequentially from the first section of the pump to the last, while the liquid pressure also increases sequentially. Modern models of multistage sectional pumps are capable of providing a liquid pumping process performance of up to 900 m3, while the pressure of the working medium created by such devices can reach up to 1900 meters of water column.

Advantages and disadvantages of centrifugal pumps

Both multi-stage and single stage pump It has a number of advantages that make these devices so popular among consumers. The advantages of the hydraulic machines under consideration include:

1. compact dimensions and light weight (since the operating shaft of the pumping equipment is directly connected to the drive motor, which eliminates the need to use additional transmission mechanisms);
2. high reliability and long service life, no need for regular maintenance;
3. minimizing the risk of pressure surges (the liquid medium pumped by pumps of this type is supplied to the pressure line in a smooth mode);
4. absence of valve elements (this makes it possible to pump contaminated liquid media containing insoluble solids);
5. simplicity of design (this is why any multi-stage or single-stage pump is affordable).

Among the disadvantages of single- and multistage pumps are:

• rather low efficiency when operating in low-capacity mode (this becomes a problem when it is necessary to pump a small volume of liquid medium under high pressure);
• impossibility of quick start-up (for such devices to start working, their working chamber must first be filled with liquid).

Basis of classification

Centrifugal pumps (both multi-stage and single-stage) are divided into different categories according to a number of their parameters and design options. So, depending on the spatial position of the axis of the working shaft, they can belong to one of the following types:

• horizontal centrifugal pumps;
• devices with a vertical working axis.

A centrifugal horizontal pump, the axis of rotation of the shaft and impeller of which is located strictly in the horizontal plane, is, as a rule, a large-sized installation used for industrial purposes. Centrifugal horizontal pumps are used to equip pumping stations, ensuring the operation of autonomous water supply systems in which such devices are used in conjunction with a hydraulic accumulator. Thus, a horizontal pump requires more space for its installation.

Centrifugal pumps with a vertical shaft and impeller axis are more common in the domestic sphere. This design can be used as a surface multi-stage pump used to service an autonomous water supply system, as well as a drainage or fecal pump.

Another criterion by which different categories are distinguished among single- and multi-stage pumps is the location of such equipment in relation to the pumped liquid medium. So, depending on this parameter, pumps can be surface (or ground), submersible and semi-submersible. Surface devices, which can be a vertical multi-stage and single-stage or a horizontal multi-stage and single-stage pump, are located on the surface of the earth, outside the well, but close to it.

Place such equipment, reliably protected from moisture, in a pit, on a specially prepared area or in a separate room. One of the most significant disadvantages of this type of pumping equipment is that it produces quite a lot of noise during operation. It should also be taken into account that surface centrifugal pumps can be chosen only if the depth of the well from which it is planned to pump water with their help does not exceed ten meters.

Submersible centrifugal pumps are completely immersed in the pumped medium during operation. Some models of vertical submersible centrifugal pumps can even be placed in a pipe through which the liquid medium is pumped out. When using submersible pumps, water from a serviced well can be lifted from a depth of 40 meters or more. Submersible pumps are capable of pumping liquid media with a capacity of up to 16 m 3 /hour, while its pressure can reach 200 meters of water column. Submersible pumps make virtually no noise during operation, since they are completely in a liquid medium.

designed for pumping stations. The most commonly used equipment in water supply installations is general purpose. For the most part, double-sided type D pumps are installed at the stations, and if large volumes are required, console devices are used.

Vertical pumps

A single-stage vertical centrifugal pump is used in buried stations, the construction of which is difficult when the water level is too close. This makes it possible to reduce the cost of construction, reduce the size of the machine room, and improve the quality of operating conditions for electric motors, which can be moved to the ground floor.

Axial pumps

Such installations are most often used for large water supplies. Sewage dynamic pumps are mostly installed at stations of household waste disposal systems. Water temperatures up to 80 degrees and a possible content of up to one percent of abrasive particles are provided. Installations of the Gr and GrU types can also be used in wastewater systems.

Centrifugal single-stage pump and its properties

The operational properties of such pumps are determined by their main parameters: power, pressure, cavitation reserve, flow, suction height. Important qualities The operation of the units is the voltage of the electric motor and the speed of the wheel.

It must be understood that the parameters of axial and centrifugal pumps are variable even with continuous action of the impeller and will depend on the flow. It is customary to show characteristics for reduced wheel diameters in the drawings. The characteristics of optimal operating points correspond to maximum efficiency. Adequate recruitment and flow are acceptable pump performance. These characteristics are included in the designation of installations.

Operating point

The operating point is the position corresponding to the current operating mode. It does not always coincide with an acceptable indicator, but it must be close to them. A single-stage centrifugal water pump always operates within the working section, which is determined according to the permissible reduction in efficiency. Operating points should only be within these limits. The characteristics of each device are described by the manufacturer with the expectation of clean water with a temperature of twenty degrees at optimal atmospheric pressure at ocean level.

Pumps types K and KM

The centrifugal single-stage type operates with a single-sided impeller located on the edge of the pump shaft. The pressure pipes rotate 90, 180, 270 degrees. This depends on the specific layout conditions. Bearings in mechanisms are lubricated with a liquid substance. The cantilever single-stage centrifugal pump can have several modifications: installation without an engine (K) and in a monoblock version (KM). After these letters, the marking indicates the flow and pressure.

Installations with two-way supply

Class D single-stage horizontal pumps with semi-scroll inlet are available on the market. The horizontal lift of the cast iron body is carried out in the plane of the shaft axis. This feature makes it possible to disassemble and repair the device without the need to dismantle the pipeline. Each two-way pump is marked with the symbol "D". After this letter two numbers are indicated: flow and pressure.

What does a console installation consist of?

A single stage centrifugal water pump consists of the following parts: casing volute, support, front cover, impeller, suction pipe, nut, shaft, oil seal bushing, ball bearing.

The principle of connecting components

With the help of relief holes, the axial pressure is partially balanced. The wheel is also equipped with an axial seal on the rear side. A tube with a branch pipe is connected to the unloading chamber. A second ball bearing is installed to fix the rotor and better perceive the unbalanced axial force. The pump seals are equipped with a hydraulic seal.

Such installations have a capacity of 28 to 100 liters per second with a head of 12 to 98 meters. High-performance single-stage pumps mostly have a two-way supply option. At normal axial pressure, a good double-flow impeller has fairly high cavitation rates.

Housing and seals

Pumps designed for pumping clean liquid with temperatures up to 80 degrees are equipped with a cast iron body with horizontal connectors along the shaft axis. Replacement o-rings are made of cast iron. The pump shaft is made of steel and rotates on one thrust and radial bearings with ring lubrication.

The oil seals are equipped with tubes that supply fluid from spiral chambers. This single-stage cantilever-type centrifugal pump has a capacity of 30 to 1800 liters per second and a head of 10 to 100 meters.

Vertical shaft units

Two brands of single-stage devices for clean water are produced: 20 HB and 28 HB. They are designed for installation in buried stations. In this installation, the heel of the electric motor absorbs axial forces. The pump seal is equipped with a hydraulic seal with soft padding. Type NV units are directly connected to electric motors or by means of solid seam couplings via an intermediate shaft. The single-stage vertical centrifugal pump has a capacity from 3240 to 10,800 cubic meters per hour and pressure from 29 to 40 meters.

Features of sewage pumps

Centrifugal single stage pump is used for pumping sewage liquid, Wastewater and sludge. One of the main reasons why pumps stop during use is their clogging. To prevent debris from getting into the mechanisms, special grilles are provided. Their installation necessitates changing the installation form.

Such pumps are sealed with steel rings with a sharp edge that cuts the fibers that get into the seals. The units are equipped with covers that provide easy access for cleaning the suction part of the impeller. The number of blades is kept to a minimum to reduce the possibility of clogging. The passages between them thus increase. Quite often the number of blades is reduced to two.

The cantilever single-stage centrifugal sewage pump is created from materials that are not susceptible to corrosion. Its body contains several connectors necessary for partial disassembly during the cleaning process. The inlet edges of the blades are very rounded. Thanks to this, fibrous bodies will not get stuck on them.

Pumps of the NF, NFuV and FV brands. Open and diagonal devices

The following standard sizes of installations are provided: 2NF, 4NF, 6NF, 8NF. Their productivity ranges from 36 to 864 cubic liters per hour with a pressure of 6.5 to 50 meters. Similarly to such installations, sewage pumps with an open impeller with two thick blades can be used. In such devices, all fibers are cut by the sharp edge of the blade.

To work with wastewater, a single-stage diagonal-type centrifugal pump is often used. The impeller in these units, as well as in models of the FV and NFuV brands, is equipped with two blades. Their productivity varies from 43 to 150 cubic meters per hour, and the pressure reaches 63 m.

Dredgers

Dredgers are used to pump mixtures of loosened soil and liquid through pipes to the required distance. Today, the market produces pumps with a transportation range of up to 5 km and a capacity of 40 to 1200 cubic meters per hour. With the help of dredgers, it is possible to develop excavations up to 15 m deep below the water horizon. These installations have a number of features due to the high concentration of large particles in the pumped water mass. For this reason, a wear-resistant wheel is created from manganese hard steel.

The single-stage vertical centrifugal pump is protected by armor on the inside of the housing to prevent rapid wear. To prevent the mechanism from becoming unusable so quickly, purified water is supplied between the wheel into the left cavity and to the oil seal through special drillings to flush out solid fragments from these places.

Radial blades are installed on the outer part of the working and covering wheel disks. They are selected so that the axial amplifier comes into balance during rotation.

Vacuum pumps

A single-stage centrifugal pump with a vacuum device is created in two main versions: dry, sucking only gas, and wet, also working with liquid. The difference can only be determined by distribution nodes. U wet pumps The dead space dimensions are much larger, so they have a higher ultimate pressure compared to dry ones. The highest rotation speed during operation is achieved by samples with a vertical shaft arrangement.

Non-self-priming device

A non-self-priming single-stage centrifugal pump is used for pumping milk or other viscous food products whose temperature does not exceed 90 degrees. The working blades of the wheel are closed and every part of such an installation that comes into contact with the liquid is made of good quality of stainless steel and other materials approved for use in the food industry. The engine is protected from water ingress by a special facing casing.

Conclusion

The centrifugal single-stage pump, the circuit of which is described in this article, can be used in the most various areas. The method of application and the materials being pumped will determine the performance characteristics of such installations, as well as the material from which the parts are made and the method of their placement in the mechanisms. The pumps can be used for the distillation of clean water, a mixture of liquid and dirt, sewage waste and food mass of various viscosities.

Mechanisms designed for pumping liquids used for food are made of quality materials, the use of which is approved by the Ministry of Health. Pumps that are used to remove sewer liquids containing large fibers are designed so that large parts are cut and do not interfere with normal operation mechanisms.

This article provides descriptions of pump designs used in water supply and sewerage systems, as well as in the main industries and utilities.

Axial pumps. Axial pumps are vane pumps in which the fluid moves through the impeller in the direction of its axis. Basic specifications axial pumps are specified in GOST 9366-80 “Axial pumps. Are common technical specifications" According to this GOST, axial pumps are manufactured in two types: with rigidly fixed wheel blades - rigid-blade pumps (type O) and with rotating wheel blades - rotary-vane pumps (type OP). The ability to change the angle of installation of the blades in OP type pumps allows you to adjust the flow and pressure of the pump over a much wider range than in O type pumps with rigidly fixed wheel blades. The high efficiency of the OP type pump is maintained.

The impeller of an axial pump consists of a streamlined sleeve on which the blades are mounted. The bushings and blades of the axial pump in the basic version are cast from cast iron or steel, and in the marine version - from bronze. Liquid enters the pump through the inlet pipe. In the inlet pipes of some types of pumps there are guide devices in the form of fixed, streamlined blades. Directly behind the impeller (along the fluid flow) there is a straightening device to eliminate the rotational movement of the fluid.
In axial pumps of type O and OP in the basic version (Fig. 2.19), the liquid is discharged at an angle of 60° to the vertical. In small-sized axial pumps, the liquid is discharged at an angle of 90°. The shaft of axial pumps of the OP type is hollow, the rod of the blade turning mechanism passes inside it. The blade turning mechanism can have a manual, electric or hydraulic drive. It should be borne in mind that in the case of a manual drive, the angle the settings of the blades can only be changed when the pump is not running. The design of the impeller of an axial pump determines the features of its operation: such pumps are designed to supply large flow rates of liquid (up to 140 thousand m3/h) at relatively low pressures (4-20 m). also determines another feature of axial pumps - in most cases they are designed to operate under flood water. Therefore, when designing. pumping units axial pumps are installed so that the impeller is located below the water level in the receiving chamber.
Axial pumps are distinguished by their simple design and compactness, lighter weight compared to centrifugal pumps, and the ability to supply contaminated liquids. The compact design is especially valuable when supplying large flows of liquid, as it allows you to significantly reduce the size of the pumping station. Axial pumps are used in irrigation installations and first lift pumping stations of water supply systems, as well as for pumping waste liquid and activated sludge at sewage treatment plants.
Sewage pumps (sewage) and soil pumps. Fecal pumps are designed for pumping wastewater, sludge and liquids contaminated with mechanical impurities in suspension. Therefore, such pumps must have sufficiently large passage channels to guarantee uninterrupted operation. For this purpose, the impellers of fecal pumps are made with a small number (2-4) streamlined blades. In addition, special hatches are installed in the housing for inspection and cleaning of the pumps.
The main parameters of centrifugal fecal pumps produced to date are specified in GOST 11379-73 “Centrifugal fecal pumps. Main parameters". According to this GOST, the production of fecal pumps of four main types is provided: horizontal type FG, vertical type FV, single-stage and two-stage.

Rice. 2.21. Vertical fecal pump
/ - pump housing; 2— base plate; 3—electric motor

A horizontal fecal single-stage cantilever pump with axial liquid supply is shown in Fig. 2.20. The pump support is made in the form of a bracket, to the flange of which a simplified body with suction and discharge pipes is attached. The suction pipe is equipped with a hatch for cleaning. The second cleaning hatch is located in the upper part of the pump housing.

The pressure pipe is usually located vertically; if necessary, it can be rotated 90° in any direction. The pump shaft rotates in rolling bearings, and for large pumps - in plain bearings. The shaft seal is an stuffing box. To cool and flush the stuffing box, as well as to create a hydraulic seal while the pump is running, water is supplied to the stuffing box. process water under pressure 0.03–0.05 MPa (0.3–0.5 kgf/cm2) exceeding the pressure in the pump discharge pipe.
Vertical fecal pumps have become widespread. Vertical pumping units with a small feed are structurally designed in the form of a block with an electric motor (Fig. 2.21). The pump shaft has upper and lower supports. In the upper support, mounted on the plate, there is a heel that absorbs the axial force of the rotating parts of the pump. The lower support is located in the pump and consists of two bearings - radial ball and textolite thrust. The pump housing is connected to the base plate using a pipe. The pump shaft runs inside the pipe. To lubricate a textolite bearing, clean (technical) water must be supplied to it.
Large vertical fecal pumps are produced with an axial supply. The pump housing is made with a connector in the horizontal plane (Fig. 2.22). As can be seen from the figure, the pump and electric motor are installed on separate foundations. Axial forces and the load from the weight of the rotating parts in such pumps are absorbed by the heel of the electric motor, located in the oil bath.
On January 1, 1983, a new GOST for pumps for waste liquids was introduced - GOST 11379-80E “Dynamic pumps for waste liquids. General technical conditions". According to this GOST, pumps of the SD - centrifugal and SDS - free-vortex types must be manufactured. Pumps of the SD type must be manufactured in horizontal and vertical versions, as well as semi-submersible. This series of pumps must provide a flow rate from 7 to 10,800 m3/h with pressures from 5.5 to 0 m when pumping liquid containing no more than 1% of abrasive particles up to 5 yul in size. The main technical characteristics of SD pumps (flow, pressure) are close to the characteristics of F-type fecal pumps.
In the designation of wastewater pumps, the first letters indicate the type of pump, the first group of numbers means flow, m3/h, the second group of numbers means pressure, m; then put the designation climatic version and GOST number. For example, a horizontal pump type SD with a flow of 100 m3/h and a head of 40 m, climatic version U4 (according to GOST 15150-69) is designated as follows: SD 100/40-U4-GOST 11379-80E. A comparison of the designations of pumps manufactured according to GOST 11379-73 and 11379-80E is given in table. 2.3.
Behind Lately In our country and abroad, to simplify the operation of pumps for pumping wastewater and other liquids containing large suspended and floating inclusions, a number of new types of pumps are being developed.

Table 2.3

Centrifugal fecal pumps are made with wheels equipped with devices (knives) for grinding large inclusions.
Such a pump, at the same time as pumping liquid, performs the function of a crusher, i.e. it is a crusher pump. The use of such pumps simplifies the operation of pumping units. This primarily concerns automated pumping stations, where the need to operate crushers and devices for removing solids trapped on grates is eliminated or significantly reduced. In our country, such a pump was developed by NIKTI MKH of the Ukrainian SSR (Kyiv).

For pumping wastewater containing inclusions large sizes, use free-vortex pumps (SVP), which, according to their operating principle, are related to vane friction pumps. These pumps differ from centrifugal pumps in that the open impeller is located in a pocket in the rear wall of the pump housing (Fig. 2.23). In this case, a chamber is formed between the end of the wheel, free from rotating parts. The width of this chamber is equal to the diameter of the pressure pipe at the level of the alignment tongue. Only part of the total flow of liquid entering the pump passes through the impeller - the so-called circulation flow, which makes up 15-25% of the pump flow. Energy is transferred to the rest of the liquid entering the pump through vortex energy exchange with the circulation flow. A wide flow cavity, free of moving parts, and an open impeller ensure that the pump practically does not clog, and therefore, the labor costs for its operation are significantly reduced. However, the efficiency of free-vortex pumps is lower than that of centrifugal pumps, amounting to 45-55%. Currently, the industry produces a free-vortex pump FGS 81/31 with a nominal flow of 81 m3/s and a submersible centrifugal monoblock fecal electric pump brand TsMF 160-10-U5 with a free-vortex impeller.
To pump pulps, as well as certain types of industrial wastewater with a large amount of heavy mechanical impurities, including abrasive ones (sand, scale, slag, etc.), soil and sand pumps are used.
Gr type single-stage cantilever-type soil pumps with a four-bladed single-entry impeller are manufactured in accordance with GOST 9075-75.
The housings of such pumps have a connector in a vertical plane. These pumps are designed for pumping pulps with a density of up to 1.3 kg/l.
The main parameters of sand centrifugal pumps are established by GOST 8388-77 “Centrifugal sand pumps. Types and basic parameters." Currently, the industry produces sand pumps of the Ps type with a flow rate of 50 to 200 m3/h for pumping pulp with a density of up to 2-3 kg/l (depending on the brand of the pump). The design of the Pr type sand pump is shown in Fig. 2.24. As can be seen from the figure, the pump housing, inlet and outlet pipes are rubberized, which prevents rapid wear of the pump.
It is necessary to supply clean water to the gland seals of Pr type pumps (as well as Gr type pumps) under a pressure equal to 0.8-1 of the operating pressure of the pump.

Recently, low-power submersible sewer electric pumps have become widespread. A series of submersible electric pumps of the TsMK type has been developed and mastered (Fig. 2.25). This is a submersible monoblock unit with a built-in electric motor, sealed against waste liquid entering the internal cavity. The pumping part is a single-stage centrifugal pump with a two-bladed impeller mounted on the cantilever part of the electric motor shaft. The pump outlet is spiral. The suction and discharge cavities are separated by a labyrinth seal.
The sewage electric pump is equipped with a special device for automatically connecting it to the pressure pipeline without the use of conventional fasteners, which allows you to dismantle the pump without emptying the well (tank) where it is installed.
In production construction work For open drainage, as well as for pumping contaminated water, including waste water, submersible monoblock centrifugal electric pumps of the GNOM type have become widespread (Fig. 2.26). According to GOST 20763-75, these pumps must be manufactured with a flow rate from 10 to 400 m3/h at pressures from 10 to 40 m.

Rice. 2.25. Submersible sewage pump type TsMK
1 - impeller; 2—spiral outlet; 3 - bearing shield; 4 - electric motor; 5 - cover; 6 - handle; 7 - electric motor cable

The impeller of the GNOM type electric pump is semi-open, cast, made of wear-resistant material, mounted on the electric motor shaft. The electric motor of a special design is asynchronous with a squirrel-cage rotor. The rotor rotates in two ball bearings installed in the upper and lower covers. Between the impeller and the lower bearing there is an oil chamber with a seal unit located in it. The oil in the chamber is intended to lubricate and cool the friction pairs of the mechanical seals. It also serves as a hydraulic shutter to prevent the pumped liquid from penetrating into the cavity of the electric motor. The presence of an oil chamber somewhat complicates the operation of GNOM type pumps compared to the operation of TsMK type pumps. The pumped liquid is sucked in by the impeller and fed into the annular slot between the electric motor and the casing. Next, the liquid enters the pressure pipe and is pumped through a rubber hose. GNOM type pumps are capable of pumping liquid with a density of up to 1250 kg/m3 with a content of solid mechanical impurities with a maximum size of up to 5 mm and up to 10% by weight.
Abroad, submersible electric pumps for pumping wastewater have become widespread. The Swedish company Flygt produces a large range of standard sizes of submersible pumps for wastewater, including large pumps with a flow rate of up to 4000 m3/h. In Fig. Figure 2.27 shows one such pump. The use of submersible pumps for pumping wastewater can significantly reduce the size of pumping stations, and therefore reduce their cost.

Pumps for chemically active liquids. Pumps of this class are intended mainly for chemical industry. In water management systems, such pumps are used to pump solutions of various reagents, primarily a coagulant solution. They are also used for pumping wastewater that is aggressive towards ferrous metals. industrial production. Types and main parameters of centrifugal pumps for chemical production specified in GOST 10168-75. Basic technical requirements for such pumps are given in GOST 15110-79E. According to these GOSTs, pumps for chemical production are manufactured of the following types:
X, AX, TX - horizontal, cantilever on a separate rack; HB - horizontal, intersupport, single-stage and multi-stage, with single-entry impellers;
HD - horizontal, intersupport, with double-entry impellers;
HI, AHI, THI - submersible, vertical, with supports outside the pumped liquid;
HP, AHP - submersible, with supports in the pumped liquid.
Pumps of the indicated types must be manufactured in the following designs: M - monoblock; P - with increased (excessive) pressure at the inlet; О - heated or cooled; C - self-priming.

For particularly chemically active liquids, single-stage centrifugal pumps are made from ceramic materials And epoxy resins. The types and main parameters of such pumps are regulated by GOST 22570-77. According to this GOST, pumps must be manufactured with a flow from 3 to 460 m3/h and a pressure from 6 to 95 m. The most common are pumps of type X, AX and GC. These pumps are manufactured using standardized support posts and bearings. In Fig. Figure 2.28 shows a cross-section of the X 20/31 pump.

1 - impeller; 2 — oil seal; 3 — protective sleeve; 4 — pump shaft; 5 — bracket

The material of the pump flow part is high-silicon alloy. The shaft protective sleeve is made of the same material.
Previously, the designations of pumps for chemical production included the diameter of the inlet pipe and the speed number. GOST 10168-75 contains a table for replacing outdated pump designations. For example, the X 20/31 pump was previously designated 2X-6, and the AX 90/19 pump was previously designated 5AX-9.

Single Stage Centrifugal Pumps

Single-stage centrifugal pump is a type of centrifugal pump that is widely used for pumping water, liquids with increased chemical activity, suspensions, emulsions in many industries. This type of pump has one stage, that is, one impeller. A single-stage pump can have one or two-way fluid supply to the impeller. Due to the rotation of the impeller, the liquid entering the pump leaves it with increased speed and increased pressure. Structurally, they are divided into horizontal and vertical single-stage centrifugal pumps. The latter have a vertical working position and create increased outlet pressure compared to horizontal ones.
Single-stage centrifugal pumps are used for urban water supply, industrial and rural water management, for field irrigation, pumping petroleum products, aviation fuel, etc.

CN MAG-M

Max. pressure 16 bar for the standard version and 150 bar for the HP version (higher values ​​are possible on request). Used for pumping (explosive) hazardous, toxic media interacting with the atmosphere. There are no seals, external flushing systems, seals or valves, but provides complete sealing even under severe operating conditions. Impellers closed type, statically and dynamically balanced, end suction. External ball bearings (L10).

MZ series magnetic coupling pumps are made of thermoplastic. Capable of maintaining constant pressure over a wide range of pumping speeds. For use in the chemical industry. Available limited opportunity dry work.

NZ Series Single Stage Horizontal End Suction Thermoplastic Pump is an economical pumping solution wide range chemicals. Mechanical seals, single (TB/RA) and double (DROTT).

Cast horizontal single-stage pumps with end suction and side discharge and volute casing. Manufacturing material - thermoplastic. For pumping low density chemicals. Excellent for use in polishing, plating, filtration, cleaning and general chemical industrial applications.

N.J.L.

NJL series pumps are made from PFA/FEP. End suction. They are an excellent alternative to expensive pumps made of heat-resistant alloys for working with corrosive and toxic media (including acids). Complies with ISO 2858 / ISO 5199 / EN 22858 standards. Single and double mechanical seals. Roller bearings.

N.J.K.

Cast pumps of the NJK series are horizontal single-stage centrifugal with end suction. Are an excellent alternative expensive pumps made of heat-resistant alloys for pumping hazardous, toxic and corrosive media. Dimensions and design comply with ISO 2858 / ISO 5199 / EN 22858 standards. Mechanical seals are single (TB/RA) and double (DROTT), oil lubrication of bearings.

N.J.R.P.

The NJRP series cast horizontal end suction pumps can be equipped with a single (TB/RA) or double (DROTT) mechanical seal. The flow part is designed to withstand high loads and pressures on the flanges. NJRP series pumps are an excellent alternative to expensive pumps for pumping hazardous, corrosive, toxic media. Complies with ISO 2858 / ISO 5199 / EN 22858 standards.