RU2637342C2 - Multistage centrifugal pump - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention relates to a multistage centrifugal pump with a base (2), a head (14) and a wall (16) that connects the base (2) to the head (14) and surrounds the pump stages around the outer perimeter. In addition, the centrifugal pump comprises of an engine frame adjacent to the head (14) for accommodating an electric motor (20) for driving a centrifugal pump. The wall (16) in the axial direction extends beyond the head (14) and is connected to the motor frame.

EFFECT: creating a simpler structure and more attractive design.

13 cl, 15 dwg

Description

The invention relates to a multistage centrifugal pump with the features shown in the restrictive part of the independent claim 1.

In this invention, well-known centrifugal pumps, for example, the CRund and CRE series of the company Grundfos, are taken as a basis. In this case, we are talking about multistage vertical centrifugal pumps, in which at least two pump stages are located in the pump housing between its base and the head, which are surrounded on the outer perimeter by a wall connecting the base to the head. At the base there are suction and pressure nozzles of a centrifugal pump. The liquid pumped by the centrifugal pump through the suction pipe first enters the first stage of the pump, and from there it goes further to the last stage of the pump, from where it again returns to the base and is discharged from the centrifugal pump through the pressure pipe. The shaft of the centrifugal pump connecting the impellers of the individual stages of the pump is hermetically withdrawn from the head part, where it is movably connected to the shaft of the drive electric motor mounted at an axial distance from the head part on the engine frame, usually made of steel casting. In these known centrifugal pumps, the engine frame is either an integral part of the head part, or detachably fixed to this head part, the engine frame being connected to the base with pin bolts.

The objective of the invention is to provide a multistage centrifugal pump of the kind described above, which, unlike the known pumps, has a simpler design and a more attractive design.

This problem is solved by means of a multistage centrifugal pump with the characteristics given in independent claim 1. Preferred modifications to this centrifugal pump are described in the dependent claims, the following description, and also in the drawings. Moreover, the characteristics given in the dependent claims and in the description, both by themselves and in a suitable combination with each other, characterize the improved technical solutions according to the independent claim 1.

The multistage centrifugal pump according to the invention has a base and a head part, between which there are at least two stages of the pump with an impeller in each of them. By such a centrifugal pump is meant preferably a vertical centrifugal pump, i.e. a centrifugal pump operating on a base with vertically oriented axes of the impellers, however, it should be emphasized that in the case of a centrifugal pump according to the invention, it can also be a centrifugal pump operating in any other position. The steps of the centrifugal pump along the outer perimeter are surrounded by a wall that connects the base to the head part and together with the base and head part forms the pump casing. In addition, the centrifugal pump of the invention has an engine frame adjacent to the head portion for receiving an electric motor for driving this centrifugal pump. On the frame, the electric motor is installed at a distance from the head in the direction of the centrifugal pump's middle axis, and the end of the pump shaft protruding from the head, connected to the impellers of the pump stages, is connected to the motor shaft in the area of the motor frame.

In contrast to the known multistage centrifugal pumps of the kind under consideration, the centrifugal pump according to the invention is also characterized in that the wall of the pump housing in the axial direction, i.e. in the direction of the middle axis of the centrifugal pump, respectively, in the direction of the axis of its impellers, extends beyond the head and is connected to the engine frame to accommodate the electric motor. Unlike conventional centrifugal pumps, the motor frame in the centrifugal pump according to the invention does not bear the head part, but the wall surrounding the centrifugal pump at the outer perimeter of the stage. Due to this, freedom of choice is significantly increased with respect to the form of execution of the centrifugal pump. This applies, for example, to the embodiment of the head part, which can be simplified structurally and technologically due to the significantly lower static load on it compared to the known centrifugal pumps. The pin bolts that were previously used to connect the engine frame to the base are no longer required in the centrifugal pump of the invention. Completely new opportunities are also opening up in terms of the design of a centrifugal pump, so that a centrifugal pump can be made much more attractive in appearance.

A structurally and technologically simple solution is obtained when the wall is preferably made in the form of a pipe into which the head part is inserted. Such a pipe can be understood as either a pipe with a welded seam or a seamless pipe, in which case the pipe can be made, for example, by deep drawing, so that the wall thickness can be easily determined. Regardless of the shape of the pipe, it is advisable to tightly connect it at one end to the base. In the pipe section adjacent to the other end of the pipe, a head is inserted at a distance from this pipe end and is also hermetically connected to the pipe. Preferably, the head is welded to the pipe in this position. In this case, the welded joint of the head part and the pipe can be provided inside the pipe, or this welded connection can be made outside the pipe.

The engine frame is preferably provided with an annular flange, which is located at the end of a portion of the wall protruding beyond the head. Preferably, this annular flange, as preferably the entire engine frame, is an aluminum die cast part. The radial dimensions of the annular flange are preferably such that the outer perimeter of the annular flange coincides with the outer perimeter of the wall, so that the annular flange radially extends only into the cross section in the light or, accordingly, in the direction of the inner cavity of the wall, but does not protrude outside the outer perimeter of the wall.

Further, it is preferable to make an annular flange in the form of a shoulder, moreover, it has a section that is included in the inner space of the wall, and a section adjacent to the end of the wall. In this case, the outer diameter of the portion entering the inner wall space corresponds to the inner diameter of the wall, so that the wall at its free end facing away from the base can rest on the radial portion entering the inner space of the wall, which gives increased stability to the wall portion forming the frame engine.

Preferably, the annular flange forms the entire engine frame. In this regard, a preferred embodiment in which this annular flange is adapted to secure the electric motor. The electric motor is mounted on the flat side of the annular flange facing away from the base. It is advisable to mount the motor on the annular flange in the region of the annular flange, which is included in the cross section in the light of the wall, where mounting means are preferably located on the side of the annular flange for fixing the motor on this annular flange. This preferably refers to through holes for receiving bolts with which the motor is screwed to the annular flange.

According to another preferred embodiment of the centrifugal pump according to the invention, said annular flange is adapted to mount various electric motors. In this regard, it is preferable to provide that in the annular flange at a first radial distance from the middle axis of the annular flange, several through holes are made in series with the distribution around the perimeter of the annular flange to provide a threaded connection with the mating flange of the first electric motor, and at least one second radial a distance other than said radial distance of said through holes, with sequential distribution along the perimeter of the annular flange, is provided additional through holes for providing a threaded connection with the counter flange of the second electric motor.

As an alternative to the preferred embodiment with an annular flange that directly forms the engine frame, an axially protruding device can be placed on the annular flange on the annular flange to form an engine frame, and a mounting flange for the electric motor is located at the end of the annular flange. This embodiment has proven to be preferable, for example, when large electric motors are used. In addition, the device axially protruding on the annular flange allows a relatively short section of the wall protruding beyond the head of the centrifugal pump, which positively affects the stiffness of this section in bending and torsion. The mounting flange located at the end of the fixture facing away from the annular flange, when using small electric motors, can be so large that it will be inside the cross section in the light of the wall, or with electric motors with large dimensions, respectively, with electric motors with large counterflanges compared with the indicated mounting flange may also protrude radially beyond the external contour of the wall.

Preferably, at least one window is formed on the wall portion extending beyond the head portion. Such a window should be understood as a large recess provided in the wall, through which the inner part of the wall is accessible for maintenance and repair in the region of the section forming the engine frame. This at least one window is thereby integrated into the wall. When choosing window sizes, it should be taken into account that the wall must support the weight of the electric motor, i.e., at least one window should not have any effect on the mechanical stability of the wall, and therefore should not be too large.

In addition, it should be borne in mind that the mechanical weakening of the wall caused by this at least one window can adversely contribute to the undesired excitation of the wall's own vibrations. To counter this, it is preferable to increase the rigidity of the wall by suitable methods. One step in this direction may be to increase the wall thickness in the portion protruding beyond the head portion compared to the thickness of the rest of the wall. As another measure, a protective function for the window cover can also be given. In addition, the mechanical structure can be stabilized by creating the corresponding mechanical deformations in the wall.

It is particularly preferable if two windows are made on the wall portion extending beyond the head part, which are arranged in such a way that a labyrinth seal is available through them, which seals the pump shaft relative to the head part, and at least one centrifugal pump air valve located on the head part. Preferably, in the centrifugal pump according to the invention, two air valves are provided on the head, which together are located in the same plane passing through the middle axis of the centrifugal pump and its head, on both sides facing away from the middle axis. In this case, both windows made in the wall of the window are preferably located diametrically opposed to each other radially outside relative to the air valves.

The head part of the centrifugal pump according to the invention is preferably made in the form of a deep drawn part, preferably made of stainless steel. As a result, a comparatively thin-walled sheet of steel and preferably stainless steel can be used for the manufacture of the head, which is preferably formed into a vaulted shape by a deep drawing process. In contrast to the head parts made so far from steel castings, the head part of the centrifugal pump according to the invention is therefore clearly lighter, which usually also positively affects the total weight of the centrifugal pump. In the case of using stainless steel, the corrosion resistance of the head is also an additional advantage.

For maintenance, cleaning or repair, it is advisable to detach the wall to the base. In this regard, it is preferable to provide that the wall was pulled together with the base using a clamping ring. In this case, preferably one section of the base extends into the end section of the wall facing away from the head and the engine frame, and the clamping ring surrounding the wall radially from the outside presses the wall against the base. For a tight seal of the wall relative to the base, it is advisable to place the seal between the wall and the base.

The clamping ring used to connect the wall to the base is preferably made circumferentially divided into several annular segments. As a result of this, the clamping ring has several annular segments which are circumferentially adjacent to each other and connected to each other, forming a clamping ring. Such a sectioned embodiment of the clamping ring is advantageous in that it allows the clamping ring to be easily positioned outside the wall and allows the transmission of force from the clamping ring to the wall.

The individual annular segments of the clamping ring are preferably made in such a way that one recess is made at their both circumferential ends directly adjacent to the corresponding end of the annular segment, the first recess on the first side being made on the first flat side of the annular segment extending perpendicular to the middle axis of the clamping ring, and the second recess is made on the second flat side facing away from the first flat side and extending parallel to this first flat side. Accordingly, in the wall-mounted state of the annular segments, one recess is facing the head portion, while the other recess is facing the base. In the region of these recesses, the annular segments of the clamping ring connected to each other are arranged overlapping each other in the axial direction and the circumferential direction of the clamping ring.

Preferably, the individual annular segments of the clamping ring are connected not only to each other, but each of them is also connected to the base. Thus, according to a further preferred embodiment of the centrifugal pump according to the invention, it is provided that these annular segments of the clamping ring, forming a connection with each other, are screwed to the base. To this end, through openings oriented in the axial direction of the clamping ring are made on both recesses of the ring segments, arranged so that in the docked state of the clamping ring and with overlapping recesses of the ring segments, these through holes formed in overlapping recesses coincide with each other. Through a common through hole formed thereby, one screw with a head is passed, which is screwed into a blind threaded hole made in the base.

Below the invention is explained in more detail on the examples presented in the accompanying drawings. In these drawings, the following is schematically, simplified, and at different scales:

FIG. 1 vertical multistage centrifugal pump, side view,

FIG. 2 is a section along lines II-II in FIG. one,

FIG. 3, the centrifugal pump of FIG. 1 and 2, top view,

FIG. 4 is a perspective view of the end portion of the centrifugal pump of FIG. 1-3 in the area of the head of a centrifugal pump,

FIG. 5 is a view in the direction V-V of FIG. four,

FIG. 6 is a perspective view of the end portion of the centrifugal pump of FIG. 1 to 3 in the area of the base of the centrifugal pump,

FIG. 7, the end portion of FIG. 6, side view,

FIG. 8 ring segment of the clamping ring, top view,

FIG. 9, the annular segment of FIG. 8, in perspective,

FIG. 10 fragment A from FIG. 2

FIG. 11 is a perspective view of a centrifugal pump unit of FIG. 1 to 3 and an electric motor for driving a centrifugal pump,

FIG. 12 is a longitudinal sectional view of an end portion of a centrifugal pump according to a second embodiment in the region of the head of the centrifugal pump,

FIG. 13 a fragment of FIG. 12, in perspective,

FIG. 14 is a longitudinal sectional view of an end portion of a centrifugal pump according to a third embodiment, in the region of the head of the centrifugal pump, and

FIG. 15 is a side view of an end portion of a pumping unit with a centrifugal pump according to a fourth embodiment.

Presented in FIG. 1-11, the multistage centrifugal pump has a base 2. This base 2 is made with two connecting flanges 4 and 6. Of these connecting flanges 4 and 6, the connecting flange 4 forms a suction pipe, and the connecting flange 6 forms a discharge pipe of the centrifugal pump.

A connecting flange 4, forming a suction pipe, surrounds the suction channel 8, which extends into the suction zone formed at the base 2, to which the suction pipe of the impeller 10 of the first stage of the centrifugal pump adjoins, which is formed by the impeller 10 and the housing surrounding it 12. The centrifugal pump as a whole contains five stages, consisting of the impeller 10 and the housing 12. These pump stages are located one above the other vertically, and the impellers 10 of these pump stages sit on one common shaft of us a wasp, which on the head part 14, located at a distance vertically from the base 2, is removed from the centrifugal pump housing on its upper side. This pump shaft is not the subject of this invention and therefore is not shown in the drawings for reasons of their better clarity.

The body of the centrifugal pump is formed not only by the base 2 and the head part 14, but also by the wall 16, which connects the base 2 to the head part 14 and surrounds the steps of the centrifugal pump at a radial distance from them. The wall 16 in this embodiment is a stainless steel pipe. As can be seen in particular in FIG. 1, 4 and 11, the wall 16 has a section 18, which in the axial direction of the centrifugal pump extends beyond the head part 14. Thus, the head part 14 is integrated into the wall 16 at a distance from the end of the wall 16 facing the base 2, and the head part 14 hermetically connected to the wall 16 by welding. Welding is performed on the inner side of the wall 16 by laser welding.

An annular flange 24 is located at the end of the section 18 of the wall 16 facing away from the base 2. The ring flange 24 forms a motor frame for the electric motor 20, and the shaft of the electric motor 20 is connected via a coupling 22 to the pump shaft not shown in the region of the section 18 of the wall 16.

In FIG. 2 it can be seen that the annular flange 24 is made in the form of a shoulder and contains a portion 26 extending inside the wall 16 and a portion 28 adjacent to the end of the wall 16. In this case, the outer profile of the portion 26 of the annular flange 24 corresponds to the inner profile of the wall 16, and the outer profile of the portion 28 of the annular the flange 24 corresponds to the outer profile of the wall 16.

The connection of the electric motor 20 with the annular flange 24 is carried out as a threaded connection. To this end, on the annular flange 24, as can be seen in particular in FIG. 4, at the same radial distance from the center of the annular flange 24, four through holes 30 are made, which extend axially in the annular flange 24 and are used to accommodate the screws with which the counterflange of the electric motor 20 is fixed on the annular flange 24. In addition, in the annular flange 24 there are four additional axially oriented through holes 32, which are located at the same radial distance from the center of the annular flange 24, and the radial distance of the through holes 32 from the center of the annular flange 24 is less than the radial distance of the through holes 30 from the center of the annular flange 24. The through holes 32 are used to fasten the electric motor, the counter flange of which is from the counter flange of the electric motor 20.

On the site 18 of the wall 16, two windows 34 are made, lying diametrically opposite to each other. Access through the windows 34 is open from the outside of the wall 16 to the inside of the wall portion 18. Thus, through these windows 34, it is possible to carry out, including installation, maintenance and repair work on the coupling 22 connecting the pump shaft to the motor shaft, as well as the labyrinth seal 36, the pump sealing shaft relative to the head part 14, and two centrifugal pumps 38 located on the head part 14 of the air valves.

On the upper side of the window 34 facing the annular flange 24, two recesses are made, in which one tongue 40 extends into the wall 16 and is designed for detachable fastening of the annular flange 24 to the wall 16. In the region of the tongue 40 overlapping the portion 26 of the annular flange 24 one through hole 42, which serves to install a screw that is screwed into a blind threaded hole made in section 26 of the annular flange 24 and in its position corresponding to the through hole 42, so that ltsevoy flange 24 fixed to wall 16.

The wall 16 at its end facing away from the head part 14 is expanded in the radial direction, the wall 16 passing through the ledge into the radially expanded section 44, the base section 46 enters this expanded section 44 of the wall 16, forming part of the flow connection between the connecting flanges 4 and 6 and a pump housing (see FIG. 2 and FIG. 10). An annular groove 48 is made on the outer perimeter of the portion 46 of the base 2, which serves to accommodate the annular seal 50, which seals the wall 16 relative to the base 2 (Fig. 2).

The wall 16 is sealed to the base 2 by means of a clamping ring 52. This clamping ring 52 is perimeter divided and contains six identical ring segments 54, the structure of which is clearly visible in FIG. 8 and FIG. 9. From FIG. 8 and FIG. 9, it can be seen that at both ends of the annular segments 54 lying on the perimeter, one recess 56, 58 is made, immediately adjacent to the corresponding end. In this case, the recess 56 is made on one flat side 60 of the ring segment 54, and the recess 58 is on the flat side of the ring segment 54 facing the flat side 60. The ring segments 54 adjacent to the flat side 60 also have one ledge 64, which the mounted state of the ring segments 54 is facing towards the center of the clamping ring 52. In the mounted state, the ring segments 54 overlap each other in the area of the recesses 56 and 58 made in these ring segments 54, and the portion of the first ring segment 54, menshenny in recesses 56 in the axial direction of the clamping ring 52 contacts the portion of the second annular segment 54, which is exactly the same in the recess area 58 is reduced in the axial direction of the clamping ring 52.

The connection of the ring segments 54 with each other is carried out by screwing. To install the necessary screws 66 in the annular segments 54 in the area of the recesses 56 and 58, through holes 68 are made that coincide with each other when adjacent ring segments 54 overlap each other in the area of the recesses 56 and 58. The screws 66 are not only used for connecting the annular segments 54 with each other, but also for tightening the clamping ring 52 on the outer side of the wall 16, which is clearly seen in FIG. 10. For tightening 10 of the clamping ring 52 on the outer side of the wall 16, the separate ring segments 54 of the clamping ring 52 are located on the outer side of the wall 16 so that they surround the ledge 70 with their shoulder 64, forming a transition to its expanded section 44 on the wall 16, and fit to six protrusions 72 radially extending from the base 2, and the through holes 68 made on overlapping portions of the annular segments 54 coincide with the blind threaded holes 74 made in the protrusions 72. To tighten the clamping ring 52 n the outer side wall 16 inserted through the through holes 68 of the ring segments 54 screws 66 are screwed into blind threaded holes 74.

Presented in FIG. 12 and FIG. 13, the centrifugal pump is different from that shown in FIG. 1-11 of a centrifugal pump is only a form of execution of the wall connecting the base 2 with the head part 14, as well as a form of execution of the engine frame and its connection with the wall. The one shown in FIG. 12 and FIG. 13 of the centrifugal pump, the wall 16 ‘extends to a lesser extent beyond the head part than the wall 16 of the centrifugal pump of FIG. 1-12, so that the portion 18 'of the wall 16' is shorter than the portion 18 of the wall 16 of the centrifugal pump of FIG. 1-12.

At the top in FIG. 12 and FIG. At the end of the wall 16 ', an annular flange 24 ‘is installed, which section 26‘ enters the wall 16 ‘and the section 28‘ adjoins the wall 16 ‘. An annular flange 24 ‘on its flat side facing away from the head part 14 carries a structure 76. The structure 76 is formed by two ribs 78 that are located on the annular flange 24 opposite to each other and extend obliquely to the middle axis X of the centrifugal pump. Of these two ribs 78 in FIG. 12 and FIG. 13, respectively, one rib 78 is visible.

At the end of the structure 76 facing off from the annular flange 24 ′, a mounting flange 80 is provided. A mounting flange 80 is used to fasten the electric motor 20, which is screwed by the counterflange to the mounting flange 80.

The annular flange 24 ', the structure 76 and the mounting flange 80 together form the engine frame for the electric motor 20, and on this engine frame through the intermediate spaces between the ribs 78 forming the structure 76, good access is provided to the coupling located between the mounting flange 80 and the annular flange 24' a pump shaft with a drive shaft of an engine 20, which in FIG. 12 and FIG. 13 is not shown, as well as partially not shown components on the head part 14.

The fastening of the motor frame of the centrifugal pump of FIG. 12 and FIG. 13 is well shown, in particular in FIG. 13. For mounting the engine frame in the wall 16 'just below the area in which the portion 261 of the annular element 24' extends into the wall 16 ', two rectangular openings 82 lying diametrically opposed to each other are made. Each of the openings 82 serves to accommodate the fastening element 84. Each fastener 84 has a main body 86 with corresponding openings 82 with a rectangular cross-section contour that extends from the outside of the wall 16 'through openings 82 into the wall 16', and an end portion 88 that extends beyond the cross-section contour I am the main body 86 and is adjacent to the outer side of the wall 16 '. Through the main body 86 of the fasteners 84 passes through one threaded hole 90, which in the installed position of the fastener 84 in the wall 16 'is oriented parallel to the middle axis X of the centrifugal pump. Corresponding to the position of the threaded hole 90 in the installed position of the fasteners 84 in the wall 16 'in the annular flange 24', two through holes 92 are made. Each of these through holes 92 serves to accommodate a head screw 94 that is screwed into the threaded hole 90 of the fastener 84, whereby the engine frame is fixed on the wall 16 '.

Presented in FIG. 14, the centrifugal pump substantially corresponds to that shown in FIG. 12 and FIG. 13 of the centrifugal pump and differs from it only in the fastening of the engine frame 20 to the wall 16 ‘. This fastening is carried out by welding the annular flange 24 'with the wall 16 in the area in which the portion 26' extends into the wall 6 '.

Presented in FIG. 15, the centrifugal pump is based essentially on the centrifugal pump of FIG. 1-11 and differs from the latter only in the form of the engine frame. The engine frame has an annular flange 24 “, different from the annular flange 24 of the centrifugal pump of FIG. 1-11 only the axial dimensions of the 28 "section. A mounting flange 80 'is mounted on the flat side of the section 28 "facing away from the wall 16. This mounting flange 80' is intended for fastening electric motors 20 with a large counterflange 96 and for this extends radially beyond the outer perimeter of the peripheral part 16. In this region, which extends beyond the outer perimeter of the peripheral part 16, the mounting flange 80 'is supported by several stiffening ribs 98, which radially protrude along the outer perimeter of the portion 28 "of the annular flange 24".

Reference List

2 - base

4 - connecting flange

6 - a connecting flange

8 - suction channel

10 - impeller

12 - case

14 - head part

16, 16 ‘- wall

18, 18 ‘- plot

20 - electric motor

22 - coupling

24, 24 ‘, 24“ - ring flange

26, 26 ‘- plot

28, 28 ‘, 28“ - section

30 - through hole

32 - through hole

34 - window

36 - labyrinth seal

38 - air valve

40 - tongue

42 - through hole

44 - plot

46 - Plot

48 - ring groove

50 - ring seal

52 - a clamping ring

54 - ring segment

56 - notch

58 - recess

60 - flat side

62 - flat side

64 - ledge

66 - screw

68 - through hole

70 - ledge

72 - ledge

74 - blind threaded hole

76 - structure

78 - rib

80.80 ‘- mounting flange

82 - opening

84 - fastener

86 - the main body

88 - end section

90 - threaded hole

92 - through hole

94 - head screw

96 - counterflange

98 - stiffener

A - fragment

X - Middle axis

Claims (13)

1. A multistage centrifugal pump containing a base (2), a head part (14), a wall (16, 16 ') that connects the base (2) to the head part (14) and which surrounds the pump steps along the outer perimeter, as well as the adjacent to the head part (14) of the engine frame to accommodate an electric motor (20), designed to drive a centrifugal pump, characterized in that the wall (16, 16 ') in the axial direction extends beyond the head part (14) and is connected to the engine frame. 2. A centrifugal pump according to claim 1, characterized in that the wall (16, 16 ') is formed by a pipe into which the head part (14) is integrated, preferably welded. 3. The centrifugal pump according to claim 1, characterized in that the engine frame contains an annular flange (24, 24 '), which is located at the end of the section (18, 18') of the wall (16, 16 '), protruding beyond the head part (14 ) 4. The centrifugal pump according to claim 3, characterized in that the annular flange (24, 24 ') is made in the form of a shoulder and has a section (26, 26') that enters the inner space of the wall (16, 16 '), and a section ( 28, 28 ') adjacent to the end of the wall (16, 16'). 5. A centrifugal pump according to claim 4, characterized in that the annular flange (24) is made for mounting an electric motor (20). 6. A centrifugal pump according to claim 3, characterized in that the annular flange (24) is made for mounting various electric motors (20). 7. A centrifugal pump according to claim 3, characterized in that an axially protruding device (76) is made on the annular flange (24 '), and at the end of the annular flange (24') there is a mounting flange (80) for the electric motor ( twenty). 8. A centrifugal pump according to any one of claims 1 to 7, characterized in that at least one window (34) is formed on the portion (18) of the wall (16) that extends beyond the head part (14). 9. A centrifugal pump according to claim 8, characterized in that two windows (24) are made in the section (18) of the wall (16) protruding beyond the head part (14), which are arranged so that there is access through these windows (34) to the labyrinth seal (36), which seals the pump shaft relative to the head part (14), as well as to at least one centrifugal pump air valve (38) located on the head part (14). 10. Centrifugal pump according to claim 8, characterized in that the head part (14) is made in the form obtained by deep drawing parts, preferably stainless steel. 11. A centrifugal pump according to any one of claims 1 to 7, characterized in that the wall (16, 16 ‘) is tightened on the base (2) with a clamp ring (52). 12. A centrifugal pump according to claim 8, characterized in that the clamping ring (52) is made divided in the circumferential direction into several ring segments (54). 13. A centrifugal pump according to claim 9, characterized in that the annular segments (54) of the clamping ring (52) are screwed to the base (2) when creating a connection with each other.

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