GB2533989A

GB2533989A - Sealing Mechanism

Info

Publication number: GB2533989A
Application number: GB1516018.7A
Authority: GB
Inventors: Wareham Paul
Original assignee: Zennex Special Products Ltd
Current assignee: Zennex Special Products Ltd
Priority date: 2014-09-09
Filing date: 2015-09-08
Publication date: 2016-07-13
Anticipated expiration: 2035-09-08
Also published as: GB2533989B; GB201516018D0; GB201411110D0

Abstract

A valve comprises a butterfly element mounted on a spindle and a seal mounted within a rigid body of substantially circular cross-section, wherein major and minor parts of the perimeter of the butterfly element respectively have first and second radii R1 and R2, with R1 being less than R2, and an external periphery of the seal comprises a groove or slot forming an expansion slot (figure 6). The groove or slot is preferably of trapezoidal cross-section. Also disclosed is a flexible intermediate bulk carrier (IBC) comprising the valve of the invention and a system comprising said flexible IBC. The IBC may comprise collapsible plastics or may comprise corrugated cardboard. The system preferably comprises a dock, bulkhead and a steaming plate. A closed cell foam gasket may be present between the valve and the dock and bulkhead.

Description

SEALING MECHANISM

This invention is concerned with a sealing mechanism particularly for use in a valve assembly for use in the transport of liquids, particularly viscous liquids which may be food grade. An example of such a sealing mechanism is trade marked Polylune. An example of such a valve assembly is trade marked Zennex.

The transport market covers a wide range of delivery methods, from very large, rigid shipping containers with flexitanks through intermediate bulk carriers, down to individual bottles, cans and bag in box consumer products. The intermediate bulk carrier (IBC) market is in turn segmented between rigid tanks and flexible containers. Investigations have focused on the latter segment.

Examples of flexible IBC's are collapsible rigid plastic containers and disposable containers having a "bag in the box arrangement' such as disposable corrugated cardboard containers. This invention is more particularly concerned with a valve assembly for flexible IBC's.

The valve containing the improved sealing mechanism is used with a dock, bulkhead and steaming plate in order to present and lock the valve to the container, provide waterproof protection when steaming the valve, protect the cardboard from overspills and to reduce bulging when used with a corrugated cardboard disposable IBC. Plastic collapsible rigid containers do not require the dock, bulkhead and steaming plate. Figures 1 to 3 show such a valve assembly having a retractable operating handle (registered design). A butterfly, seal, seal housing is present inside a valve body.

The integrity and sealing of the butterfly element in any valve naturally depends upon the interference between the butterfly element, seal and main valve body. More interference allows for moulding/production/design inaccuracies and increases friction to the operation. Friction results in wear and the stressing of the other components such as through the weld of a gland to a liner. The whole thinking behind the sealing geometry needs to change to better suit a moulding process and this type of valve. New geometry needs to be developed to seal effectively with lower friction.

After much time and effort an improved sealing geometry to better suit this type of valve and a moulding process has been designed, established and tested, giving rise to numerous performance and cost improvements. This geometry seeks to combine effective sealing with lower friction. Resolving the sealing-friction relationship contradiction was the most difficult and complicated feature to design and develop. The new geometry is founded on three important principles established by a combination of conventional physics, our engineering knowledge and design experience: i. Rubber does not compress-the rubber has to "flow" ii. Interference needs to be variable across the surface of the sealing area iii. Friction should be variable and proportional to the moment of force required to overcome it.

According to the invention a sealing mechanism for a valve comprises a butterfly element and a seal mounted within a relatively rigid body of substantially circular cross section, the butterfly element being sealingly engageable with the seal, the butterfly element being pivotal on a spindle between a position sealingly engaging an internal periphery of the seal whereby the valve is closed and a position not engaging the seal whereby said valve is open, the spindle being housed within the butterfly element. the spindle further projecting from diametrically opposite regions of the butterfly element, characterised in that firstly a major part of the perimeter of the cross section of the butterfly element follows a circular path having a fixed constant radius RI and a minor part of the perimeter of the cross section of the butterfly element corresponding to the two regions uniformly distributed about the two diametrically opposite regions follows a circular path having a fixed constant radius R2, radius R2 being greater than radius R1, the portions of said perimeter between the major and minor parts constituting shoulder regions forming a smooth gradual transition between the radii of the major and minor parts and secondly that an external periphery of the seal adjacent the body comprises at least one groove or slot for flow relief when the butterfly element engages the seal.

The butterfly element is illustrated in more detail in figure 4.and 5.

The butterfly element may be a section through two spheres of radii R1 and R2 having a common centre which can be tangentially connected.

RI and R2 may be proportional to the cross sectional area of the butterfly element. Further the distance from and perpendicular to the central longitudinal axis of the spindle to the boundaries of the minor parts with the shoulder regions may be proportional to the cross sectional area of the butterfly element. Still further the distance from and perpendicular to the central longitudinal axis of the spindle to the boundaries of the major parts with the shoulder region may be proportional to the cross sectional area of the butterfly element.

The difference between R1 and R2 may correspond to 5 to 10% of the cross sectional area of the seal.

The radius R2 may be calculated to interfere with said seal by 10%.

The shoulder region corresponds to a smooth gradual transition between the radii of the major and minor parts and gives rise to a slice through the spherical geometry of the butterfly element, the slice being in the form of a cone.

Further the sealing geometry comprises a groove or expansion slot in the external peripheral surface of the seal adjacent the valve body. Figure 6 shows a cross section of contact between butterfly and seal. Figure 7 shows a sectional view of the valve seal expansion slot.. Although figure 7 shows a groove of trapezoidal cross-section, it may be of other cross-sections. The seal may comprise a rubber or thermoplastic elastomer and may be formed by injection moulding.

The butterfly element and the body are preferably formed of materials having low coefficient of volumetric /linear expansion for dimensional stability under heating. Best performance occurs with use of the same materials for both the butterfly element and the valve body, and where present, the dock, bulkhead and steaming plate, so that they expand and contract at the same rate. Suitable materials are plastics such as nylon, other polyamides and PBT or metal.

Figure 8 shows a Zennex valve dock, bulkhead and steaming plate and figure 9 a side view of a dock, bulkhead and steaming plate, the locking plate being screw threaded. The bulkhead may be in two parts to allow firm fitting to a disposable IBC. The bulkhead may have an evacuation spout to expel condensate. A closed cell foam gasket may be present between the valve and the dock and bulkhead. Figure 10 shows a dock and steaming plate with valve in place, the valve outlet having a cover with a knurled edge.

Claims

Claims 1. A sealing mechanism for a valve comprising a butterfly element and a seal mounted within a relatively rigid body of substantially circular cross section, the butterfly element being sealingly engageable with said seal, said butterfly element being pivotal on a spindle between a position sealingly engaging an internal periphery of said seal whereby said valve is closed and a position not engaging said seal whereby said valve is open, said spindle being housed within said butterfly element. said spindle further projecting from diametrically opposite regions of said butterfly element, characterised in that firstly a major part of the perimeter of the cross section of said butterfly element follows a circular path having a fixed constant radius R1 and a minor part of the perimeter of the cross section of said butterfly element corresponding to said two regions uniformly distributed about said two diametrically opposite regions follows a circular path having a fixed constant radius R2, radius R2 being greater than radius R1, the portions of said perimeter between said major and minor parts constituting shoulder regions forming a smooth gradual transition between the radii of said major and minor parts and secondly that an external periphery of said seal adjacent said body comprises at least one groove or slot for flow relief when the butterfly element engages the seal.
2. A sealing mechanism according to claim 1 wherein said butterfly element is a section through two spheres of radii R1 and R2 having a common centre which are tangentially connected.
3. A sealing mechanism according to claims 1 or 2 wherein R1 and R2 are proportional to the cross sectional area of said butterfly element.
4. A sealing mechanism according to any one of claims 1 to 3 wherein the distance from and perpendicular to the central longitudinal axis of said spindle to the boundaries of said minor parts with said shoulder regions is proportional to the cross sectional area of said butterfly element.
5. A sealing mechanism according to any one of claims 1 to 4 wherein the distance from and perpendicular to the central longitudinal axis of said spindle to the boundaries of said major parts with said shoulder parts is proportional to the cross sectional area of said butterfly element.
6. A sealing mechanism according to claims 1 to 5 wherein the difference between R1 and R2 corresponds to 5 to 10% of the cross sectional area of said seal.
7. A sealing mechanism according to claims 1 to 6 wherein radius R2 is calculated to interfere with said seal by 10%.
8. A sealing mechanism according to any one of claims 1 to 7 wherein said groove is of trapezoidal cross section.
9. A sealing mechanism according to any one of claims 1 to 8 wherein said seal comprises rubber or thermoplastic elastomer.
10. A sealing mechanism according to any one of claims 1 to 9 wherein said butterfly element and said body are formed of materials having low coefficient of volumetric/linear expansion for dimensional stability under heating.
11. A sealing mechanism according to any one of claims Ito 10 wherein the same material is used for said butterfly element and said body.
12. A sealing mechanism according to any one of claims 10 or 11 wherein said material comprises nylon, other polyamides, or PBT or metal.
13. A valve assembly comprising a sealing mechanism according to claims 1 to 12.
14. A flexible intermediate bulk carrier comprising a sealing mechanism according to claims 1 to 12 or a valve assembly according to claim 13.
15. A flexible intermediate bulk carrier according to claim 14 wherein said bulk carrier comprises collapsible plastic.
16. A flexible intermediate carrier according to claim 15 wherein said bulk carrier comprises corrugated cardboard.
17. A system comprising a flexible intermediate carrier according to claim 16 comprising a dock, bulkhead and a steaming plate to present and anchor the valve assembly to the carrier, provide waterproof protection when steaming the valve assembly and protect the cardboard from overspills and reduce bulging of the cardboard.
18. A system according to claim 17 wherein the dock, bulkhead and steaming plate are formed of materials having low coefficient of volumetric/linear expansion for dimensional stability under heating.
19. A system according to claim 18 wherein the same material is used for said dock, bulkhead and said steaming plate.
20. A system according to claim 19 wherein said material comprises nylon, other polyamides or PBT or metal.
21. A system according to claims 17 to 20 wherein said bulkhead is in two parts to allow firm fitting to a disposable IBC.
22. A system according to claims 17 to 21 wherein said bulkhead has an evacuation spout to expel condensate.
23. A system according to claims 17 to 22 wherein a closed cell foam gasket is present between said valve and said dock and bulkhead.Amendments to the Claims have been filed as follows: Claims * * * 1. A butterfly element suitable for use in a valve comprising said butterfly element and a resilient seal mounted within a relatively rigid body of substantially circular cross section, said butterfly element being sealingly engageable with said seal, said butterfly element being pivotal on a spindle between a position sealingly engaging an internal periphery of said seal whereby said valve is closed and a position not engaging said seal whereby said valve is open, said spindle being housed within said butterfly element, said spindle further projecting from diametrically opposite regions of said butterfly element cross section, characterised in that a major part of the perimeter of the cross section of said butterfly element follows a circular path having a fixed constant radius R1 and a minor part of the perimeter of the cross section of said butterfly element corresponding to two areas uniformly distributed about said two diametrically opposite regions follows a circular path having a fixed radius R2, radius R2 being greater than radius R1, the portions of said perimeter between said major and minor parts constituting shoulder parts forming a smooth gradual transition between the radii of said major and minor parts.2. A valve comprising a butterfly element and a resilient seal mounted within a relatively rigid body of substantially circular cross section, the butterfly element being sealingly engageable with said seal, said butterfly element being pivotal on a spindle between a position sealingly engaging an internal periphery of said seal whereby said valve is closed and a position not engaging said seal whereby said valve is open, said spindle being housed within said butterfly element, said spindle further projecting from diametrically opposite regions of said butterfly element, characterised in that firstly a major part of the perimeter of the cross section of said butterfly element follows a circular path having a fixed constant radius RI and a minor part of the perimeter of the cross section of said butterfly element * 4,0 * * * **00 * * * ** * * ID *** * corresponding to two areas uniformly distributed about said two diametrically opposite regions follows a circular path having a fixed constant radius R2, radius R2 being greater than radius R1, the portions of said perimeter between said major and minor parts constituting shoulder regions forming a smooth gradual transition between the radii of said major and minor parts and secondly that an external periphery of said seal adjacent said body comprises at least one groove or slot for flow relief when the butterfly element engages the seal.3. A butterfly element according to claim 1 corresponding to a section through two spheres of radii R1 and 122 having a common centre which are tangentially connected.4. A butterfly element according to claims 1 or 3 wherein R1 and R2 are proportional to the cross sectional area of said butterfly element.5. A butterfly element according to any one of claims 1, 3 or 4 wherein the distance from and perpendicular to the central longitudinal axis of said spindle to the boundaries of said minor parts with said shoulder regions is proportional to the cross sectional area of said butterfly element.6. A butterfly element according to any one of claims 1 or any one of 3 to 5 wherein the distance from and perpendicular to the central longitudinal axis of said spindle to the boundaries of said major parts with said shoulder parts is proportional to the cross sectional area of said butterfly element.7. A valve comprising a butterfly element according to any one of claims 3 too.8. A valve comprising a butterfly element according to claims 1 or any one of 3 to 6 wherein the difference between R1 and R2 corresponds to 5 to 10% of the cross sectional area of said seal.9. A valve according to claims 8 wherein radius R2 is calculated to interfere with said seal by 10%.10. A valve according to claim 2 or any one of claims 7 to 9 wherein said groove is of trapezoidal cross section. * *** * * **** * * * ** * * * *** * **** 11. A valve according to claim 2 or any one of claims 7 to 10 wherein said seal comprises rubber or thermoplastic elastomer.12. A butterfly element according to claims 1 or any one of 3 to 6 formed of material having low coefficient of volumetric/linear expansion for dimensional stability under heating.13. A valve according to claim 2 or any one of claims 7 to 11 wherein said butterfly element and said body are formed of materials having low coefficient of volumetric/linear expansion for dimensional stability under heating.14. A valve according to any one of claims 2 or any one of 7 to 11 or 13 wherein the same material is used for said butterfly element and said body.15. A butterfly element according to claim 12 wherein said material comprises nylon, other polyamides or PBT or metal.16. A valve according to any one of claims 13 or 14 wherein said material comprises nylon, other polyamides, or PBT or metal.17. A flexible intermediate bulk carrier comprising a valve according to claims 2 or any one of claims 7 to 11,13 or 16.18. A flexible intermediate bulk carrier according to claim 17 wherein said bulk carrier comprises collapsible plastic.19. A flexible intermediate carrier according to claim 17 wherein said bulk carrier comprises corrugated cardboard.20. A system comprising a flexible intermediate carrier according to claim 19 comprising a dock, bulkhead and a steaming plate to present and anchor the valve assembly to the carrier, provide waterproof protection when steaming the valve assembly and protect the cardboard from overspills and reduce bulging of the cardboard.21. A system according to claim 20 wherein the dock, bulkhead and steaming plate are formed of materials having low coefficient of volumetric/linear expansion for dimensional stability under heating. * *** * * **** a * * * * * * *** * 22. A system according to claim 21 wherein the same material is used for said dock, bulkhead and said steaming plate.23. A system according to claim 22 wherein said material comprises nylon, other polyarnides or PBT or metal.
24. A system according to claims 20 to 23 wherein said bulkhead is in two parts to allow firm fitting to a disposable IBC.
25. A system according to claims 20 to 24 wherein said bulkhead has an evacuation spout to expel condensate.
26. A system according to claims 20 to 25 wherein a closed cell foam gasket is present between said valve and said dock and bulkhead. * ** * a * **** * ** * * a/io* * **** **^**