Valve body

Abstract

A valve body defining a longitudinal axis and comprising: (i) a central valve body portion comprising: (a) a valve seat engagement surface, (b) a support surface extending from the valve seat engagement surface, and (c) a valve stem extending from the support surface along the longitudinal axis; and (ii) an annular support mounted on the support surface around the valve stem and defining: (a) a stem aperture through which an upper portion of the valve stem extends, (b) an upper cap portion and (c) a frusto-conical portion extending from the valve seat engagement surface to the upper cap portion.

Description

[0001] VALVE BODY

[0002] FIELD OF INVENTION

[0003] This invention relates to a valve body. It also relates to a valve including that valve body.

[0004] BACKGROUND OF THE INVENTION

[0005] One type of valve is a self-actuated valve. A self-actuated valve is designed to open when there is only a small pressure differential across the valve, such as less than 100 kPa (1 bar). This pressure differential only has to overcome the force acting to close the valve, which is typically gravitational force and, where a spring is used to assist closing, the force of the spring that urges the valve to the closed position. Unlike actuated valves, that can open when there is a large pressure difference across the valve, a self-actuated valve has specific design constraints.

[0006] Self-actuated valves have been available for many decades, and there are many design variations of these valves.

[0007] One particularly challenging environment for self-actuating valves to operate in is in pumping slurries. Slurries are two-phase fluids that include solid particles suspended in liquid, for example, as a paste or as a settling slurry. Slurries typically have a solids concentration of at least 5% by weight. In valves, abrasive wear is typically the dominant wear type (particularly at the area where the valve seat meets the valve body), and is particularly problematic when pumping slurries having a relatively high solids concentration of hard or abrasive particles. Self-actuating valves are not suitable for use in pumping pastes, such as two phase mixtures having a yield stress higher than approximately 100 Pascals.

[0008] One consideration in valve design relates to the valve stem and the valve body, which are typically formed as a unitary component. To seat a self-actuating valve body correctly on the valve seat, guidance is needed, which is typical provided by a stem portion at the top of the valve body. In some circumstances, the valve stem portion can shear from the rest of the valve body, causing premature failure of the valve.

[0009] It is among the objects of an embodiment of this invention to provide means which may at least ameliorate this problem or provide a useful alternative. SUMMARY

[0010] This summary is provided to introduce a selection of concepts that are further described in the detailed description below. This summary is not intended to identify indispensable features of the claimed subject matter, nor is it intended for use as an aid in limiting the scope of the claimed subject matter.

[0011] In this application ordinal numbers (first, second, third, etc.) are assigned arbitrarily herein, and are used to differentiate between parts, and do not indicate a particular order, sequence, or importance.

[0012] According to a first aspect there is provided a valve body defining a longitudinal axis and comprising: (i) a central valve body portion comprising (a) a valve seat engagement surface, (b) a support surface extending from the valve seat engagement surface, and (c) a valve stem extending from the support surface along the longitudinal axis; and (ii) an annular support mounted on the support surface around the valve stem and defining: (a) a stem aperture through which an upper portion of the valve stem extends, (b) an upper cap portion, and (c) a frusto-conical portion extending downward and outwards from the upper cap portion to the valve seat engagement surface, and wherein the upper cap portion and the frusto-conical portion of the annular support define a valve ring mounting area.

[0013] Optionally, the valve stem has a first diameter at a lower portion thereof, and a second, narrower, diameter at an upper portion thereof. The first diameter (also referred to as the annular support diameter) may be similar to (i.e. approximately the same size or slightly smaller than) the stem aperture diameter defined by the annular support.

[0014] Optionally, the upper cap portion extends beyond the support surface, and optionally also beyond the valve seat engagement surface.

[0015] Optionally, the upper cap portion and the frusto-conical portion define a valve ring mounting area.

[0016] Optionally, the upper cap portion defines a lower surface (optionally substantially planar), extending from the frusto-conical portion to a lateral sidewall thereof. In some embodiments, a valve ring, when mounted thereon, is in contact with at least 40% of the lower surface of the upper cap portion. In other embodiments, the valve ring, when mounted, may be in contact with at least 50%, 55%, 60% or even 70% of the lower surface of the upper cap portion. Optionally, the support surface and the valve stem lower portion are joined at a transition zone providing stress concentration relief. Optionally, the transition zone includes an external radius larger than a machining tool imparted radius. Optionally, the external radius is at least 3mm. The combination of the transition zone external radius and an enlarged lower portion diameter provides increased stress concentration relief, thereby reducing the potential for fatigue breakage or snapping of the valve stem.

[0017] Optionally, the valve body may further comprise a valve ring mounted on the frusto-conical portion.

[0018] Optionally, the valve ring may comprise an elastomeric seal mounted as an interference fit on the frusto-conical portion.

[0019] Optionally, the valve seat engagement surface defines a circumferential nose where the seat engagement portion meets the frusto-conical portion.

[0020] Optionally, the elastomeric seal protrudes radially beyond the circumferential nose.

[0021] Optionally, the central valve body portion may further comprise an alignment feature extending in an opposite direction to the stem along the longitudinal axis.

[0022] Optionally, the alignment feature comprises a central base and an alignment leg extending downwards therefrom to assist with centralising the valve body. Optionally, a plurality of alignment legs extend downwards and outwards therefrom to assist with centralising the valve body.

[0023] Optionally, the upper cap portion and the frusto-conical portion define an arcuate surface therebetween. In embodiments where a valve ring is mounted on the frusto-conical portion, the valve body may define an expansion cavity between the valve ring and the arcuate surface.

[0024] Optionally, the upper cap portion of the annular support defines at least one venting aperture extending therethrough; in some embodiments a plurality of venting apertures, such as three venting apertures, may be used.

[0025] Optionally, the upper cap portion includes a lower surface that slopes downwards (i.e. towards the valve seat engagement surface) towards the periphery thereof.

[0026] Optionally, the valve stem includes a threaded profile on a lower part thereof. Optionally, the annular support defines a threaded portion on the stem aperture complementary to the valve stem threaded profile so that the annular support may be screwed onto the valve stem to maintain the valve body in close-coupled relation. Alternatively, the annular support may be secured to the valve stem using a different mechanism, such as a clamp, a weld, or any other convenient fixture.

[0027] Optionally, the annular support is only secured to the central valve body portion at the valve stem (e.g. at the lower part so that other portions of the annular support are free to move relative to the central valve body portion.

[0028] Optionally, an underside of the frusto-conical portion is able to move (for example, slide) relative to the support surface when the threaded portion is secured to the valve stem.

[0029] Optionally, the upper cap portion includes an upper surface that includes engagement features to enable a screw tool to engage therewith and enable a user or machine to screw the annular support onto the valve stem.

[0030] Optionally, the annular support comprises a unitary component. Alternatively, the annular support comprises a plurality of components coupled together. Optionally, one component comprises a generally planar upper cap portion having a stem aperture therein. The upper cap portion optionally defines engagement features. Optionally, another component comprises a frusto-conical body coupled to an underside of the generally planar upper cap portion. Where a two-part annular support is used, the valve stem may include a threaded portion extending above the frusto conical body.

[0031] Optionally, the central valve body portion is formed as a unitary component, for example, by casting or forging. Alternatively, multiple components may be coupled (e.g. friction welded) to form the central valve body portion.

[0032] Optionally, the support surface extends from the valve seat engagement surface at a support angle (defined with respect to a horizontal plane). The support angle may be an angle selected from the range of between 1 and 40 degrees; preferably between 5 and 25 degrees; in some embodiments between 6 and 15 degrees, and in one embodiment approximately 10 degrees.

[0033] Optionally, the frusto-conical portion includes an upwards sloping underside defining an annular recess. Alternatively, or additionally, the support surface may define an annular recess. Optionally, a seal, such as an elastomeric seal (e.g. an O- ring) may be located within the recess, or within both recesses where opposing recesses are used. Additionally or alternatively, a lock (such as adhesive) may be used on the threaded portion to provide a seal.

[0034] Optionally, an underside of the frusto-conical portion has a complex profile including an upwards sloping outer portion and a generally planar inner portion. Where an 0-ring recess is used, this may be located at or in the generally planar inner portion, or at or in the upwards sloping outer portion.

[0035] During operation of the valve body portion (both opening and closing of the valve), trapped particles and the flow of fluid tend to force the valve stem out of alignment, particularly at an upper part thereof, which creates a bending stress concentration at a lower part of the valve stem, leading to potential fatigue crack failure at the lower part. By using a larger stem radius at the lower portion and a frusto- conical portion, the frusto-conical portion distributes the stress concentration and reduces the potential for fatigue crack failure at the lower portion of the valve stem. Using a separate support surface that can be releasably clamped to the central valve body portion at the stem makes the valve body more stiff, thereby providing additional support to the valve stem and reducing the risk of the valve stem being sheared during operation (i.e. during opening and closing). Clamping the frusto-conical portion at the stem (but not at the upwards-sloping underside) allows relative movement of the frusto-conical portion and the valve seat engagement surface, which may assist in reducing stress concentrations.

[0036] An ideal valve stem would have a combination of high hardness (for wear resistance) and high toughness (for impact load resistance); however, such a combination is not practically available. As a result, ideal designs would have high toughness at the valve stem and high hardness at the contact point of the valve stem and an upper support or guide. It is expensive to create a composite material having these properties, or to process the valve stem material so that it has these properties (e.g. case hardening). However, by securing the annular support to the central valve body portion at the valve stem, the effective acting stress applied to the transition zone is reduced, even without changing the properties of the valve stem material, so that the allowable stress of the unchanged material is not exceeded. This reduction in acting stress reduces the potential for fatigue breakage or snapping of the valve stem. According to a second aspect there is provided a valve comprising: a valve seat defining a flow path therethrough; and a valve body according to the first aspect.

[0037] Optionally, the valve comprises a self-actuated valve.

[0038] According to a third aspect there is provided a pump including one or more valves according to the second aspect.

[0039] BRIEF DESCRIPTION OF THE DRAWINGS

[0040] These and other aspects of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

[0041] Figure 1 is a sectional elevation view of a self-actuated valve body in accordance with an embodiment of the invention;

[0042] Figure 1 B is an enlarged view of part of the self-actuated valve body of Figure 1 ;

[0043] Figure 2 is a perspective view of a part (the annular support) of the valve body of Figure 1 ;

[0044] Figure 3 is a simplified sectional view of a valve comprising the valve body of Figure 1 mounted in a valve housing, with the valve body in the closed position; and

[0045] Figure 4 is a simplified sectional view of the valve of Figure 3, with the valve body in the open position.

[0046] DETAILED DESCRIPTION OF EMBODIMENTS

[0047] Reference will now be made to the drawings, in which reference numeral 10 indicates a valve body according to one embodiment of the present invention. In this embodiment the valve body 10 comprises a self-actuated valve, but in other embodiments the valve body 10 may be used in an actuated valve.

[0048] The self-actuated valve body 10 defines a longitudinal axis 12, and includes a central valve body portion 20 comprising: (a) a valve seat engagement surface 22, (b) a support surface 24 extending from the valve seat engagement surface 22, and (c) a valve stem 26 extending along the longitudinal axis 12 from the support surface 24.

[0049] The support surface 24 extends at support angle 28 of approximately 10 degrees to the horizontal, as best seen in Figure 1 B.

[0050] In this embodiment, the central valve body portion 20 is formed as a unitary component, for example, by casting; but in other embodiments, multiple components may be coupled together, for example by welding, to form the central valve body portion 20. The valve stem 26 comprises a lower portion 30 having a first diameter (also referred to as the annular support diameter), and an upper portion 32 having a second, narrower, diameter (also referred to as the stem diameter) than the first diameter. The lower portion 30 includes a screw thread profile 34.

[0051] As best seen in Figure 1 B, a transition zone 36 is provided where the support surface 24 meets the valve stem lower portion 30. The transition zone 36 includes an external radius larger than a typical radius imparted by a machining tool after casting or fabrication of the central valve body portion 20. In this embodiment, the external radius is at least 4mm. The combination of the transition zone external radius and the lower portion diameter (which is larger than a typical valve stem diameter) provides increased stress concentration relief, thereby reducing the potential for fatigue breakage or snapping of the valve stem 26.

[0052] As also shown in Figure 2, the self-actuated valve body 10 further comprises: an annular support 40 removably mounted on the support surface 24 and defining: (a) a stem aperture 42 through which the upper portion 32 of the valve stem 26 protrudes and surrounding the lower portion 30 of the valve stem 26, (b) an upper cap portion 44 and (c) a frusto-conical portion 48 extending downwards and outwards from the upper cap portion 44.

[0053] The valve seat engagement surface 22 and the frusto-conical portion 48 meet at, and define, a circumferential nose 50.

[0054] The upper cap portion 44 extends radially beyond the valve seat engagement surface 22 and also beyond the support surface 24 and the circumferential nose 50. In other embodiments, however, the upper cap portion 44 may not extend beyond one or more of the valve seat engagement surface 22, the support surface 24, or the circumferential nose 50.

[0055] The upper cap portion 44 and the frusto-conical portion 48 define an arcuate surface 52 therebetween, and also define a valve ring mounting area, shown generally by numeral 54 in Figure 2.

[0056] The annular support 40 (in this embodiment, the stem aperture 42) includes a screw thread profile 56 (best seen in Figure 2) which is complementary to, and operable to engage with, the screw thread profile 34 on an outer surface of the lower portion 30 of the valve stem 26 so that the annular support 40 may be screwed onto the valve stem 26 to maintain the valve body 10 in close-coupled relation. The upper cap portion 44 includes a lower surface 60 that is generally planar, or slopes slightly downwards (i.e. towards the valve seat engagement surface 22) from the arcuate surface 52 towards a periphery 62, e.g. at an angle of approximately 2 degrees.

[0057] The upper cap portion 44 includes an upper surface 64 that is substantially planar (i.e. flat) across its surface, except for engagement features 66 upstanding (or protruding) therefrom. The engagement features 66 enable a tool to be used to screw the annular support 40 onto the central valve body portion 20 so that a relatively high torque may be applied by the tool and thereby couple those parts securely together. In other embodiments, the engagement features may comprise recesses in the upper surface 64.

[0058] The frusto-conical portion 48 includes an upwards sloping underside 68 complementary to the central valve body portion support surface 24, onto which it is mounted.

[0059] The frusto-conical portion 48 also defines an annular recess 70 into which an O-ring 72 is mounted. The O-ring 72 ensures that there is a seal between the support surface 24 of the central valve body portion 20 and the upwards sloping underside 68 of the annular support 40. In other embodiments, the annular recess may be defined by the support surface 24, and the O-ring 72 may be located therein. The advantage of providing a seal between the support surface 24 and the upwards sloping underside 68 is that it prevents, or at least reduces, pressure leakage through the screw threaded profiles 34, 56 (which in this embodiment are metal to metal contact surfaces) when the valve is closed. In other embodiments, the annular recess into which an O-ring is mounted may be formed in the upper surface 24, or co-operating recesses (facing each other) may be formed in each of the upper surface 24 and the upwards-sloping underside 68 of the frusto-conical portion 48.

[0060] A valve ring 80, which is an elastomeric seal in this embodiment, is mounted on the annular support 40 (in particular, on the frusto-conical portion 48) as an interference fit, and is located within the valve ring mounting area 54 (Figure 2). The elastomeric seal 80 protrudes radially beyond the circumferential nose 50. An expansion cavity 82 is defined between the elastomeric seal 80 and the arcuate surface 52. When the valve body 10 is closed, the elastomeric seal 80 can deform into the expansion cavity 82. In this embodiment, the elastomeric seal 80 is in contact with at least 40% of the lower surface 60 of the upper cap portion 44.

[0061] The upper cap portion 44 also defines one or more venting apertures 84 extending therethrough and providing a fluid communication channel near the arcuate surface 52 and from the expansion cavity 82 to an area above the valve body 10.

[0062] In this embodiment, the annular support 40 comprises a unitary component, but in other embodiments, the annular support 40 may comprise a plurality of components coupled together. For example, one component may comprise a generally planar upper cap portion having a stem aperture therein and defining engagement features; another component may comprise a frusto-conical body coupled to an underside of the generally planar upper cap portion.

[0063] The central valve body portion 20 further comprises an alignment feature 90 extending along the longitudinal axis 12 in an opposite direction to the valve stem 26.

[0064] The alignment feature 90 comprises a central base 92 and a plurality of alignment legs 94 extending downwards and outwards therefrom to assist with centralising the valve body 10. In this embodiment, four alignment legs are used (only three are visible in the cross section views of Figures 1 , 3 and 4), but other embodiments may use a greater or smaller number of legs.

[0065] To assemble the valve body 10, the elastomeric seal 80 is mounted onto the annular support 40, and the combination is placed over the valve stem 26 onto the central valve body portion 20. An engagement tool (not shown) is engaged with the engagement features 66 and rotated to screw the screw thread profile 56 of the stem aperture 42 onto the complementary screw thread profile 34 on the lower portion 30 of the valve stem 26 until the central valve body portion 20 and the annular support 40 are securely clamped together. Adhesive may be used to lock the screw threaded profiles 34, 56 together, alternatively or additionally, a lock weld, tag weld, or deformation may be used on the screw threaded profiles 34, 56 for the same purpose.

[0066] Reference is now made to Figure 3, which is a simplified sectional view of a valve 100 comprising the valve body 10 of Figure 1 mounted in a valve housing, generally indicated by numeral 110, with the valve body 10 in the closed position.

[0067] A first fluid port, indicated generally by numeral 122 (in this embodiment an inlet), and a second fluid port, indicated generally by numeral 124 (in this embodiment an outlet) are each defined by the housing 110, and a flow path extends through the housing 110 and connects the fluid ports 122, 124 in flow communication. In this embodiment, the inlet 122 is oriented transverse (perpendicular) to the outlet 124, but other orientations are possible.

[0068] The housing 110 defines a chamber 126 through which fluid, particularly slurry (a liquid containing particles), is transported from the inlet 122 to the outlet 124. In this embodiment, the solids concentration of the slurry is approximately 35% by weight, but in other embodiments, the solids concentration may be as low as 5% or as high as 70%..

[0069] The valve 100 further includes a valve seat, generally indicated by reference numeral 128, which is positioned between the two fluid ports 122, 124. In one embodiment, the valve seat 128 may be formed by a hardened surface in the housing. In another embodiment, shown in the drawings, the valve seat 128 is formed by an insert mounted on the housing 110 which facilitates replacement of the valve seat 128 when worn. A pair of elastomeric O-rings 130 are located between the valve seat 128 and the housing 110. A fluid channel 132 is provided to allow hydraulic fluid to assist in removing the valve seat 128 when desired.

[0070] The valve seat 128 is a conventional annular valve seat, and defines a part of the flow path. The valve seat 128 comprises a frusto-conical upper portion 140 having a narrow end 142 and a wider end 144, and a generally cylindrical lower portion 146 extending downwards from the narrow end 142 of the frusto-conical portion 140. In other embodiments, the valve seat 128 may have a different shape.

[0071] A valve housing cover 160 is provided to close the chamber 126 above the valve body 10. A clamping plate portion 162 defines (i) a support portion 164 mounted to an underside of the valve housing cover 160, and (ii) cylindrical guide 166 extending downwards from the support portion 164, and located generally centrally thereon. The cylindrical guide 166 defines a central guide channel 168 therein, and an outer cylindrical surface 170. The central guide channel 168 is in fluid communication with the chamber 126. A wear resistant cylindrical guide bush 172 is mounted at an entrance of the central guide channel 168 as an interference fit thereto. A coil spring 174 is mounted around the outer cylindrical surface 170. Inner radial surfaces of the engagement features 66 act to centre the coil spring 174 and help to retain it in position. In other embodiments, the cylindrical guide bush 172 may be mounted and held in place by a circlip. Reference is now also made to Figure 4, which is a simplified sectional view of the valve 100, with the valve body 10 in the open position.

[0072] When the valve body 10 moves to the closed position, the secure clamping of the central valve body portion 20 and the annular support 40 by the complementary screw thread profiles 34, 56 reduces the contact stresses at the lower portion 30 of the valve stem 26. The increased diameter of the lower portion 30 (compared with the upper portion 32, which has a conventional diameter for that size of valve body) also helps to resist the effects of contact stresses, including resisting shearing of the valve stem 26.

[0073] Various modifications to the above described embodiments may be made within the scope of the present invention. For example, a different type of securing mechanism than the screw thread profiles 34, 56 may be used in other embodiments.

[0074] In other embodiments, the valve 10 may be mounted in an inverse orientation to that shown in Figures 3 and 4 (e.g. upside down), or at an angle. If mounted upside down then gravity will assist with opening the valve 10.

[0075] LIST OF REFERENCE NUMERALS

[0076] Self-actuated valve body 10

[0077] Longitudinal axis 12

[0078] Central valve body portion 20

[0079] Valve seat engagement surface 22

[0080] Support surface 24

[0081] Valve stem 26

[0082] Support angle 28

[0083] Lower portion (of valve stem) 30

[0084] Upper portion (of valve stem) 32

[0085] Screw thread profile (of valve stem upper portion) 34

[0086] Transition zone 36

[0087] Annular support 40

[0088] Stem aperture (of annular support) 42

[0089] Upper cap portion (of annular support) 44

[0090] Frusto-conical portion (of annular support) 48

[0091] Circumferential nose 50

[0092] Arcuate surface 52 Valve ring mounting area 54

[0093] Screw thread profile (of stem aperture) 56

[0094] Lower surface (of upper cap portion) 60

[0095] Periphery (of upper cap portion) 62

[0096] Upper surface (of upper cap portion) 64

[0097] Engagement features (of annular support) 66

[0098] Upwards sloping underside (of frusto-conical portion) 68

[0099] Annular recess (of sloping underside) 70

[0100] O-ring 72

[0101] Valve ring (elastomeric seal) 80

[0102] Expansion cavity 82

[0103] Venting apertures 84

[0104] Alignment feature 90

[0105] Central base (of alignment feature) 92

[0106] Alignment legs (of alignment feature) 94

[0107] Valve 100

[0108] Valve housing 110

[0109] First fluid port (e.g. inlet) 122

[0110] Second fluid port (e.g. outlet) 124

[0111] Housing chamber 126

[0112] Valve seat 128

[0113] O-rings 130

[0114] Fluid channel 132

[0115] Frusto-conical upper portion (of valve seat) 140

[0116] Narrow end (of frusto-conical upper portion) 142

[0117] Wider end (of frusto-conical upper portion) 144

[0118] Cylindrical lower portion (of valve seat) 146

[0119] Valve housing cover 160

[0120] Clamping plate portion 162

[0121] Support portion (of clamping plate portion) 164

[0122] Cylindrical guide (of clamping plate portion) 166

[0123] Central guide channel (of cylindrical guide) 168

[0124] Outer cylindrical surface (of cylindrical guide) 170 Wear resistant cylindrical guide bush 172

[0125] Coil spring 174

Claims

CLAIMS1 . A valve body defining a longitudinal axis and comprising:(i) a central valve body portion comprising:(a) a valve seat engagement surface,(b) a support surface extending from the valve seat engagement surface, and(c) a valve stem extending from the support surface along the longitudinal axis; and(ii) an annular support mounted on the support surface around the valve stem and defining:(a) a stem aperture through which an upper portion of the valve stem extends,(b) an upper cap portion, and(c) a frusto-conical portion extending downward and outwards from the upper cap portion to the valve seat engagement surface, and wherein the upper cap portion and the frusto-conical portion of the annular support define a valve ring mounting area.

2. A valve body according to claim 1 , wherein the valve stem has a first diameter at a lower portion thereof, and a second, narrower, diameter at an upper portion thereof.

3. A valve body according to claim 2, wherein the support surface and the valve stem lower portion are joined at a transition zone providing stress concentration relief.

4. A valve body according to claim 3, wherein the transition zone includes an external radius larger than 3mm.

5. A valve body according to any of claims 2 to 4, wherein the annular support comprises a threaded portion that co-operates with a threaded portion of the lower portion of the valve stem so that the central valve body portion is secured at the valve stem.

6. A valve body according to any of claims 1 to 3, wherein the annular support is only secured to the central valve body portion at the valve stem so that otherportions of the annular support are free to move relative to the central valve body portion.

7. A valve body according to claim 5, wherein an underside of the frusto-conical portion is able to move relative to the support surface when the threaded portion is secured to the valve stem.

8. A valve body according to any of claims 1 to 7, wherein the upper cap portion extends beyond the support surface, and also beyond the valve seat engagement surface.

9. A valve body according to any preceding claim, wherein the upper cap portion and the frusto-conical portion define a valve ring mounting area.

10. A valve body according to any preceding claim, wherein the valve seat engagement surface defines a circumferential nose where the seat engagement portion meets the frusto-conical portion.

11. A valve body according to any preceding claim, wherein the upper cap portion and the frusto-conical portion define an arcuate surface therebetween.

12. A valve body according to any preceding claim, wherein the upper cap portion includes a lower surface that slopes downwards towards a periphery thereof.

13. A valve body according to any preceding claim, wherein the upper cap portion includes an upper surface including an engagement feature.

14. A valve body according to any preceding claim, wherein the support surface extends from the valve seat engagement surface at a support angle selected from the range of between 1 and 40 degrees.

15. A valve body according to any preceding claim, wherein the frusto-conical portion includes an upwards sloping underside defining an annular recess, and the valve body further comprises a seal located therein.

16. A valve body according to any preceding claim , wherein the central valve body portion includes an alignment feature comprising a central base and a plurality of alignment legs extending downwards and outwards therefrom to assist with centralising the valve body.

17. A valve body according to any preceding claim, wherein the valve body further comprises a valve ring mounted on the frusto-conical portion.

Images