M-shaped sealing opening ring of centrifugal pump

Abstract

The invention relates to the field of centrifugal pumps, in particular to an M-shaped sealing wear ring of a centrifugal pump, and a pump body wear ring comprises a pump body wear ring cover ring, a pump body wear ring sheet and a pump body wear ring gasket; the impeller wear ring comprises an impeller wear ring cover ring, an impeller wear ring sheet and an impeller wear ring gasket; a first operation gap is formed between the pump body wear ring cover ring and the impeller wear ring cover ring which correspond to each other, a second operation gap is formed between the pump body wear ring ring piece and the impeller wear ring ring piece which correspond to each other, the first operation gap linearly extends in the axial direction, and the section of the second operation gap is in a V shape. Therefore, a continuous M-shaped labyrinth channel is formed between the pump body wear ring and the impeller wear ring, on the premise of ensuring that the design of an operation gap meets the requirement, the backflow prevention and leakage prevention capacity is effectively improved, the efficiency and the operation stability of the centrifugal pump are improved, the channel gap is larger than that of a common wear ring, no flowing dead zone exists in the gap, and the service life of the centrifugal pump is prolonged. Particulate matters are easy to pass through and are not easy to accumulate, so that the device has more advantages under silt and particle conditions.

Description

Technical Field

[0001] The invention relates to the field of centrifugal pumps, and in particular to an M-type sealing ring for a centrifugal pump. Background Art

[0002] In a centrifugal pump, the mouth ring (also known as the sealing ring or clearance ring) is a key structural element located between the pump body and the impeller. Its main function is to prevent fluid leakage, reduce axial force and ensure sealing effect by forming a seal and gap control between the impeller and the pump casing. During the high-speed rotation of the centrifugal pump impeller, a small radial displacement may occur due to thermal expansion, manufacturing errors or installation deviations. If the mouth ring gap is too small, the impeller may directly contact the pump casing, causing severe wear, damage or even pump failure. Appropriate mouth ring gap provides space to accommodate these deviations, prevents mechanical interference between components, and improves the operating reliability and service life of the pump.

[0003] The design of the ring and its clearance size have an important influence on the performance of the centrifugal pump. The size and shape of the centrifugal pump's ring clearance directly affect the pump's leakage, efficiency and operating stability. Especially in the pursuit of high efficiency and low energy consumption of pump design, the optimization of the ring clearance is particularly critical.

[0004] Existing centrifugal pump mouth rings, such as the utility model patent with application number CN202420679481.2, discloses a fixed-axis metal magnetic pump, in which the pump body and the impeller are respectively equipped with replaceable wear-resistant pump body mouth rings and impeller mouth rings, such as the patent Figure 1 As shown, the pump body mouth ring and the impeller mouth ring are both straight cylindrical mouth rings. The existing centrifugal pump mouth ring has a simple structure and cannot effectively prevent liquid backflow and leakage, which affects the efficiency and operation stability of the pump. Summary of the invention

[0005] The object of the present invention is to provide an M-type sealing mouth ring for a centrifugal pump, which improves the hydraulic performance of the pump while ensuring that the mouth ring gap meets the operating clearance, so as to solve the defects mentioned in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A centrifugal pump M-shaped sealing ring, comprising a pump body ring and an impeller ring that cooperate with each other, the pump body ring comprising two pump body ring cover rings arranged along the axial direction, a plurality of pump body ring ring sheets evenly spaced are arranged between the two pump body ring cover rings, and a pump body ring gasket is respectively arranged between two adjacent pump body ring ring sheets and between the pump body ring cover ring and the adjacent pump body ring ring sheet; the impeller ring comprises two impeller ring cover rings arranged along the axial direction, a plurality of impeller ring ring sheets evenly spaced are arranged between the two impeller ring cover rings, the impeller ring sheets correspond to the pump body ring sheets one by one, and an impeller ring gasket is respectively arranged between two adjacent impeller ring ring sheets and between the impeller ring cover ring and the adjacent impeller ring ring sheet;

[0008] A first operating gap is provided between the pump body mouth ring cover ring and the impeller mouth ring cover ring, a second operating gap is provided between the pump body mouth ring sheet and the impeller mouth ring sheet, the first operating gap extends in a straight line along the axial direction, the cross-section of the second operating gap is V-shaped, the second operating gap is provided with two flow channels symmetrically arranged along the axial direction, one end of the two flow channels are connected to each other; correspondingly, annular grooves are respectively provided between the pump body mouth ring gasket and the impeller mouth ring gasket, and the annular grooves connect the operating gaps located on the opposite sides thereof.

[0009] As a further improvement, the two flow channels are distributed at ninety degrees.

[0010] As a further improvement, the V-shaped openings of the cross sections of two adjacent second operating gaps are arranged opposite to each other.

[0011] As a further improvement, the radial width of the first operating clearance is A, the axial thickness of the pump body mouth ring gasket and the impeller mouth ring gasket are both B, the axial thickness of the pump body mouth ring sheet and the impeller mouth ring sheet are both C, the radial width of the second operating clearance is D, the radial width of the annular groove is E, the maximum axial displacement of the impeller is S, and the minimum value of the first operating clearance is K when the impeller has the maximum axial displacement S; B≥S, C=2D, E≥1.5C, K=DS≥A.

[0012] As a further improvement, the pump body mouth ring cover ring, the pump body mouth ring ring sheet, and the pump body mouth ring gasket are coaxially arranged and fit in pairs; the impeller mouth ring cover ring, the impeller mouth ring ring sheet, and the impeller mouth ring gasket are coaxially arranged and fit in pairs.

[0013] As a further improvement, the inner diameters of the two pump body ring cover rings are consistent with the inner diameter of the pump body ring gasket, or the outer diameters of the two impeller ring cover rings are consistent with the outer diameter of the impeller ring gasket, or the inner diameter of one of the pump body ring cover rings is consistent with the inner diameter of the pump body ring gasket, and the outer diameter of one of the impeller ring cover rings is consistent with the outer diameter of the impeller ring gasket.

[0014] As a further improvement, the pump body mouth ring piece includes an alternately arranged pump body mouth ring piece I and a pump body mouth ring piece II, the inner circle of the pump body mouth ring piece I is surrounded by a first V-shaped groove, and the inner circle of the pump body mouth ring piece II is surrounded by a first V-shaped protrusion.

[0015] As a further improvement, the impeller ring segment includes an impeller ring segment I and an impeller ring segment II that are arranged alternately, the outer ring of the impeller ring segment I is surrounded by a second V-shaped protrusion, and the outer ring of the impeller ring segment II is surrounded by a second V-shaped groove.

[0016] As a further improvement, the impeller mouth ring segment I and the impeller mouth ring segment II correspond to the pump body mouth ring segment I and the pump body mouth ring segment II respectively, the maximum inner diameter of the pump body mouth ring segment II is consistent with the inner diameter of the pump body mouth ring gasket, and the minimum outer diameter of the impeller mouth ring segment I is consistent with the outer diameter of the impeller mouth ring gasket.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The V-shaped second operating gap connects the annular grooves on both sides thereof, thereby forming a continuous M-shaped labyrinth channel between the pump body mouth ring and the impeller mouth ring. On the premise of ensuring that the design of the operating gap meets the requirements, the anti-backflow and anti-leakage capabilities between the pump body mouth ring and the impeller mouth ring are effectively improved, thereby improving the efficiency and operation stability of the centrifugal pump. The channel gap between the pump body mouth ring and the impeller mouth ring is larger than that of ordinary mouth rings, and there is no flow dead zone inside the gap, so particles are easy to pass through but not easy to accumulate, which is more advantageous under mud and particle conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0021] Figure 2 yes Figure 1 The enlarged schematic diagram of the pump body mouth ring and impeller mouth ring in part I;

[0022] Figure 3 is a schematic diagram of an impeller according to an embodiment of the present invention when the impeller has a maximum axial displacement;

[0023] Figure 4 It is the head curve diagram of different mouth rings;

[0024] Figure 5 It is the shaft power curve of different rings;

[0025] Figure 6 This is the efficiency curve of different mouth rings.

[0026] In the figure: 1-pump casing; 2-impeller; 3-pump body mouth ring; 4-impeller mouth ring; 5-pump body mouth ring cover ring; 6-pump body mouth ring ring piece; 61-pump body mouth ring ring piece I; 62-pump body mouth ring ring piece II; 611-first V-shaped groove; 621-first V-shaped protrusion; 7-pump body mouth ring gasket; 8-impeller mouth ring cover ring; 9-impeller mouth ring ring piece; 91-impeller mouth ring ring piece I; 92-impeller mouth ring ring piece II; 911-second V-shaped protrusion; 921-second V-shaped groove; 10-impeller mouth ring gasket; 11-annular groove; 12-first operating clearance; 13-flow channel; 14-second operating clearance. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] like Figures 1 to 3 As shown, an M-type sealing ring of a centrifugal pump includes a pump body ring 3 and an impeller ring 4 that cooperate with each other, and the pump body ring 3 is nested outside the impeller ring 4; the impeller ring 4 is sleeved on the outer wall of the impeller 2 inlet, and the pump body ring 3 is embedded in the inner wall of the pump casing 1 of the centrifugal pump.

[0029] like Figure 2As shown, the pump body mouth ring 3 includes two pump body mouth ring cover rings 5 ​​arranged in the axial direction, a plurality of pump body mouth ring slices 6 arranged evenly spaced are arranged between the two pump body mouth ring cover rings 5, and pump body mouth ring gaskets 7 are respectively arranged between two adjacent pump body mouth ring slices 6 and between the pump body mouth ring cover ring 5 and the adjacent pump body mouth ring slices 6. In this embodiment, the pump body mouth ring cover ring 5, the pump body mouth ring slice 6, and the pump body mouth ring gasket 7 are coaxially arranged in annular shapes and fit in pairs, and the outer diameters of the pump body mouth ring cover ring 5, the pump body mouth ring slice 6, and the pump body mouth ring gasket 7 are consistent, and a step surface for abutting against one of the pump body mouth ring cover rings 5 ​​is provided on the inner wall of the pump housing 1, and the other pump body mouth ring cover ring 5 can be fixedly installed on the pump housing 1 by screws, so that the pump body mouth ring slice 6 and the pump body mouth ring gasket 7 located on the inner side are pressed by the two pump body mouth ring cover rings 5.

[0030] The impeller ring 4 includes two impeller ring cover rings 8 arranged in the axial direction, a plurality of impeller ring segments 9 evenly spaced are arranged between the two impeller ring cover rings 8, the impeller ring segments 9 correspond one to one with the pump body ring segments 6, and impeller ring gaskets 10 are respectively arranged between two adjacent impeller ring segments 9 and between the impeller ring cover ring 8 and the adjacent impeller ring segments 9. In this embodiment, the impeller ring cover ring 8, the impeller ring piece 9, and the impeller ring gasket 10 are coaxially arranged in annular shapes and fit in pairs. The inner diameters of the impeller ring cover ring 8, the impeller ring piece 9, and the impeller ring gasket 10 are consistent. A step surface for abutting one of the impeller ring cover rings 8 is provided on the outer wall at the inlet of the impeller 2. The other impeller ring cover ring 8 can be fixed on the outer wall at the inlet of the impeller 2 by screws, so that the impeller ring piece 9 and the impeller ring gasket 10 located on the inner side are pressed by the two impeller ring cover rings 8.

[0031] Operating gaps are respectively provided between the corresponding pump body ring cover ring 5 and the impeller ring cover ring 8, and between the corresponding pump body ring piece 6 and the impeller ring piece 9, and multiple operating gaps are staggered in the radial direction; annular grooves 11 are respectively provided between the corresponding pump body ring gasket 7 and the impeller ring gasket 10, and the annular grooves 11 connect the two operating gaps located on the opposite sides thereof.

[0032] In this embodiment, the running clearance includes:

[0033] A first operating gap 12 is located between the corresponding pump body mouth ring cover ring 5 and the impeller mouth ring cover ring 8, and the first operating gap 12 extends in an axial straight line;

[0034] And, the pump body mouth ring piece 6 includes a staggered pump body mouth ring piece I 61 and a pump body mouth ring piece II 62, the inner ring of the pump body mouth ring piece I 61 is surrounded by a first V-shaped groove 611, and the inner ring of the pump body mouth ring piece II 62 is surrounded by a first V-shaped protrusion 621; the impeller mouth ring piece 9 includes a staggered impeller mouth ring piece I 91 and an impeller mouth ring piece II 92, the outer ring of the impeller mouth ring piece I 91 is surrounded by a second V-shaped protrusion 911, and the outer ring of the impeller mouth ring piece II 92 is surrounded by a second V-shaped groove 921; the pump body mouth ring Ring piece I61 corresponds to impeller mouth ring piece I91, and pump body mouth ring piece II62 corresponds to impeller mouth ring piece II92. With this structure, two flow channels 13 symmetrically arranged along the axial direction are formed between the corresponding pump body mouth ring piece I61 and the impeller mouth ring piece I91, and between the corresponding pump body mouth ring piece II62 and the impeller mouth ring piece II92. One ends of the two flow channels 13 are interconnected to form a second operating gap 14 with a V-shaped cross-section, and the V-shaped openings of the cross-sections of two adjacent second operating gaps 14 are arranged back to back.

[0035] With the above structure, the V-shaped second operating gap 14 connects the annular grooves 11 on both sides thereof, thereby forming a continuous M-shaped labyrinth channel between the pump body mouth ring 3 and the impeller mouth ring 4. On the premise of ensuring that the design of the operating gap meets the requirements, the anti-backflow and anti-leakage capabilities between the pump body mouth ring 3 and the impeller mouth ring 4 are effectively improved, thereby improving the efficiency and operation stability of the centrifugal pump. The channel gap between the pump body mouth ring 3 and the impeller mouth ring 4 is larger than that of ordinary mouth rings, and there is no flow dead zone inside the gap, so particles are easy to pass through and not easy to accumulate, which is more advantageous under mud and particle conditions.

[0036] In this embodiment, the two flow channels 13 are distributed at a 90-degree angle.

[0037] In this embodiment, the maximum inner diameter of the pump body mouth ring piece II 62 is consistent with the inner diameter of the pump body mouth ring gasket 7, and the minimum outer diameter of the impeller mouth ring piece I 91 is consistent with the outer diameter of the impeller mouth ring gasket 10, so that adjacent second operating gaps 14 are staggered radially.

[0038] In this embodiment, when the number of pump body ring segments 6 and impeller ring segments 9 are both odd numbers, the inner diameters of the two pump body ring cover rings 5 ​​are consistent with the inner diameter of the pump body ring gasket 7, or the outer diameters of the two impeller ring cover rings 8 are consistent with the outer diameter of the impeller ring gasket 10; or when the number of pump body ring segments 6 and impeller ring segments 9 are both even numbers, the inner diameter of one of the pump body ring cover rings 5 ​​is consistent with the inner diameter of the pump body ring gasket 7, and the outer diameter of one of the impeller ring cover rings 8 is consistent with the outer diameter of the impeller ring gasket 10, so that the two first operating gaps 12 are staggered with the adjacent second operating gaps 14.

[0039] In this embodiment, the radial width of the first operating gap 12 is A, the axial thickness of the pump body ring gasket 7 and the impeller ring gasket 10 is B, the axial thickness of the pump body ring plate 6 and the impeller ring plate 9 is C, the radial width of the second operating gap 14 is D, the radial width of the annular slot 11 is E, the maximum axial displacement of the impeller is S, and the minimum value of the first operating gap 12 is K when the impeller has the maximum axial displacement S; B≥S, C=2D, E≥1.5C; and when the impeller has the maximum axial displacement S, if Figure 3 As shown, in order to avoid the corresponding pump body mouth ring piece 6 and impeller mouth ring piece 9 from colliding with each other, K=DS≥A, that is, D≥A+S.

[0040] CFD numerical calculations were carried out to verify the improvement of pump efficiency:

[0041] Examples:

[0042] Taking OHA80-400 pump as an example, the design point flow rate is 284m 3 / h, speed 2980r / min, diameter of the mouth ring gap is 207mm, according to "API 610" gap A = 0.5mm, the axial length L of the mouth ring is 22mm, and the performance of the original mouth ring is obtained through CFD calculation after installation, with a maximum efficiency of 71.81%.

[0043] Application case A: According to the original axial ring size L = 22mm, the maximum axial displacement of the impeller is S = A = 0.5mm, B = 1mm (≥S), D = 1mm (≥S+A), C = 2D = 2mm (≥2B = 2mm), E = 5.5mm (≥1.5C = 3mm).

[0044] Application case B: The axial ring size is L=22.5mm, the maximum axial displacement of the impeller is S=A=0.5mm, B=0.5mm (≥S), D=1mm (≥S+A), C=2D=2mm (≥2B=2mm), E=5.5mm (≥1.5C=3mm).

[0045] Application case C: The axial ring size is L=22.5mm, the maximum axial displacement of the impeller is S=A=0.5mm, B=0.5mm (≥S), D=1.5mm (≥S+A), C=2D=3mm (≥2B=2mm), E=5.5mm (≥1.5C=4.5mm).

[0046] Application case D: The axial ring size is L=22.5mm, the maximum axial displacement of the impeller is S=A=0.5mm, B=0.5mm (≥S), D=1mm (≥S+A), C=2D=2mm (≥2B=2mm), E=5.5mm (≥1.5C=4.5mm).

[0047] Based on the same CFD calculation method, the hydraulic performance under the above different mouth ring conditions was obtained, as shown in Table 1.

[0048] Table 1 shows the pump efficiency values ​​under different fluid conditions.

[0049]

[0050] It can be seen from Table 1 that the technical solution of the present application can improve the pump efficiency. Figure 4 The comparison results of the lift under different flow conditions show that the mouth ring designed by the patented invention improves the lift under each flow condition. Figure 5 This is the shaft power curve. It can be seen that under different flow conditions, the mouth ring designed by the patented invention reduces the shaft power. Figure 6 This is the pump efficiency curve. It can be seen that under different flow conditions, the mouth ring designed by the patent of the present invention improves the pump efficiency and does not change the highest efficiency flow point.

[0051] Table 2 shows the efficiency improvement values ​​at different flow rates. It can be seen that the increase in the number of stacking layers of the pump body ring segment 6 and the impeller ring segment 9 can continuously improve the pump efficiency. For example, compared with the rated flow rate of ring D of ring B, the 3 / h, the efficiency improvement value is increased from 7.48% to 8.05%, so when using the patented method of the present invention, the number of stacking layers of the pump body mouth ring segments 6 and the impeller mouth ring segments 9 can be increased as much as possible under the condition that the axial size L of the mouth ring allows.

[0052] Table 2

[0053]

[0054]

[0055] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An M-shaped sealing ring for a centrifugal pump, comprising a pump body ring (3) and an impeller ring (4) that cooperate with each other, characterized in that: The pump body mouth ring (3) comprises two pump body mouth ring cover rings (5) arranged along the axial direction, a plurality of pump body mouth ring ring sheets (6) arranged at even intervals are arranged between the two pump body mouth ring cover rings (5), and a pump body mouth ring gasket (7) is respectively arranged between two adjacent pump body mouth ring ring sheets (6) and between the pump body mouth ring cover ring (5) and the adjacent pump body mouth ring ring sheet (6); the impeller mouth ring (4) comprises two impeller mouth ring cover rings (8) arranged along the axial direction, a plurality of impeller mouth ring ring sheets (9) arranged at even intervals are arranged between the two impeller mouth ring cover rings (8), the impeller mouth ring sheets (9) correspond to the pump body mouth ring sheets (6) one by one, and an impeller mouth ring gasket (10) is respectively arranged between two adjacent impeller mouth ring ring sheets (9) and between the impeller mouth ring cover ring (8) and the adjacent impeller mouth ring ring sheet (9); A first operating gap (12) is provided between the pump body mouth ring cover ring (5) and the impeller mouth ring cover ring (8), and a second operating gap (14) is provided between the pump body mouth ring plate (6) and the impeller mouth ring plate (9). The first operating gap (12) extends in a straight line along the axial direction, and the cross section of the second operating gap (14) is V-shaped. The second operating gap (14) is provided with two flow channels (13) symmetrically arranged along the axial direction, and one end of the two flow channels (13) is connected to each other; correspondingly, annular grooves (11) are respectively provided between the pump body mouth ring gasket (7) and the impeller mouth ring gasket (10), and the annular grooves (11) connect the operating gaps located on opposite sides thereof.

2. The centrifugal pump M-shaped sealing ring according to claim 1, characterized in that: The two flow channels (13) are distributed at a 90-degree angle.

3. The centrifugal pump M-shaped sealing ring according to claim 1, characterized in that: The V-shaped openings of the cross sections of two adjacent second operating gaps (14) are arranged opposite to each other.

4. The centrifugal pump M-shaped sealing ring according to claim 1, characterized in that: The radial width of the first operating clearance (12) is A, the axial thickness of the pump body mouth ring gasket (7) and the impeller mouth ring gasket (10) is B, the axial thickness of the pump body mouth ring plate (6) and the impeller mouth ring plate (9) is C, the radial width of the second operating clearance (14) is D, the radial width of the annular groove (11) is E, the maximum axial displacement of the impeller is S, and when the impeller has the maximum axial displacement S, the minimum value of the first operating clearance (12) is K; B≥S, C=2D, E≥1.5C, K=DS≥A.

5. The centrifugal pump M-shaped sealing ring according to claim 1, characterized in that: The pump body mouth ring cover ring (5), the pump body mouth ring ring sheet (6), and the pump body mouth ring gasket (7) are coaxially arranged and fit in pairs; the impeller mouth ring cover ring (8), the impeller mouth ring ring sheet (9), and the impeller mouth ring gasket (10) are coaxially arranged and fit in pairs.

6. The M-shaped sealing ring for a centrifugal pump according to claim 1, characterized in that: The inner diameters of the two pump body mouth ring cover rings (5) are consistent with the inner diameter of the pump body mouth ring gasket (7), or the outer diameters of the two impeller mouth ring cover rings (8) are consistent with the outer diameter of the impeller mouth ring gasket (10), or the inner diameter of one of the pump body mouth ring cover rings (5) is consistent with the inner diameter of the pump body mouth ring gasket (7), and the outer diameter of one of the impeller mouth ring cover rings (8) is consistent with the outer diameter of the impeller mouth ring gasket (10).

7. The centrifugal pump M-shaped sealing ring according to claim 1, characterized in that: The pump body mouth ring piece (6) comprises a pump body mouth ring piece I (61) and a pump body mouth ring piece II (62) which are arranged alternately, wherein the inner circle of the pump body mouth ring piece I (61) is surrounded by a first V-shaped groove (611), and the inner circle of the pump body mouth ring piece II (62) is surrounded by a first V-shaped protrusion (621).

8. The M-shaped sealing ring for a centrifugal pump as claimed in claim 7, characterized in that: The impeller ring piece (9) comprises an impeller ring piece I (91) and an impeller ring piece II (92) which are arranged alternately, wherein the outer ring of the impeller ring piece I (91) is surrounded by a second V-shaped protrusion (911), and the outer ring of the impeller ring piece II (92) is surrounded by a second V-shaped groove (921).

9. The centrifugal pump M-shaped sealing ring according to claim 8, characterized in that: The impeller mouth ring piece I (91) and the impeller mouth ring piece II (92) correspond to the pump body mouth ring piece I (61) and the pump body mouth ring piece II (62) respectively, the maximum inner diameter of the pump body mouth ring piece II (62) is consistent with the inner diameter of the pump body mouth ring gasket (7), and the minimum outer diameter of the impeller mouth ring piece I (91) is consistent with the outer diameter of the impeller mouth ring gasket (10).

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