GB2045947A

GB2045947A - Sealing means for gas meters

Info

Publication number: GB2045947A
Application number: GB7937891A
Authority: GB
Original assignee: United Gas Industries Ltd
Current assignee: United Gas Industries Ltd
Priority date: 1978-11-09
Filing date: 1979-11-01
Publication date: 1980-11-05
Also published as: GB2045947B

Abstract

A gas-measuring unit for a dry gas meter comprises a pair of dished pans 11, 15 having facing flanges 12, 16 secured together with a flexible diaphragm 18 therebetween. To ensure a good seal between the flanges a ribbon 20 of viscous gasket material is applied directly to one of the flanges before the flanges are secured together. One of the flanges may have a groove 13 which is filled with the gasket material, the other flange having a ridge which bites into the material in the groove. Suitable viscous materials are room-temperature vulcanizing silicon rubbers, polysulphides or polyurethanes. <IMAGE>

Description

SPECIFICATION Sealing means This invention relates to a method of providing a gas-tight seal in a gas-measuring unit of a dry gas meter.

The invention provides a method of making a gas-measuring unit for a dry gas meter of the kind comprising a pair of dished pans having facing flanges and a flexible diaphragm gripped between the flanges, including the step of applying a viscous liquid of a kind which sets or cures to form a resilient, gas-resistant solid gasket directly to at least one of the facing flange surfaces in a continuous ribbon, and securing the facing flanges together with the diaphragm therebetween.

Said method of applying the liquid may be by rolling or brushing or dipping or spraying or by gun application. The dished pans may be secured together either after or before the liquid is fully cured or set. The pans may be secured together by separate clips. Alternatively, one pan may have an integral clip means which resiliently engages over the other, for instance by bent-over tabs.

The invention also extends to a dry gas meter when formed by the method referred to above.

Specific embodiments of the invention are shown in the accompanying drawings, in which: Figure 1 is a diagrammatic scrap representation of part of a double-chamber unit for a gas meter, and Figures 2 and 3 are diagrammatic scrap representations of a different double-chamber unit for a gas meter.

Gas-measuring units for dry gas meters, for instance as described in Patent No. 1,165,151, comprise a pair of dished steel pans secured together about their edges, with a flexible diaphragm dividing one pan from the other. As shown in Figure 1, one of the dished pans 11 has a flange 12 running around its periphery with a groove 13 in the flange. The other pan 15 also has a flange 16, but this flange has a ridge 17 running around it, the ridge 17 being located and of a size to seat in the groove 13. A flexible diaphragm 18 of synthetic rubber extends across the pans, between the flanges 12, 16, and has a depending skirt 19 around its periphery serving to locate it relative to the pans.

A problem with this type of dished pan is that the flanges are frequently not flat and so to obtain a gas-tight seal it is usual to mould a rubber gasket to the periphery of the synthetic diaphragm. Such a process is difficult and costly and results in high reject levels. The sealing problem is solved according to this invention by forming a gasket from a liquid which is disposed directly onto a flange, thereby enabling the peripheral gasket of the diaphragm to be omitted. The liquid may be any viscous liquid which is sufficiently viscous to stay in place on the flange and which sets or cures to a resilient solid and which is gas resistant. For instance, room temperature vulcanizing silicon rubbers, either cured by reaction with air or by mixing two components, may be used.Alternatively, polysulphides or polyurethanes are suitable, as are hot-melt applied sealants which set as they cool.

The liquid is applied to the flange 12 in a continuous ribbon by rolling or brushing or spraying or by gun application to form a layer 20. The layer 20 may be at a minimum to just fill the groove 13 or may, as shown, have a thickness of up to 1 mm on the surface of the flange. The layer 20 may be left to set before the pans are assembled, but alternatively may be assembled when still semi-fluid.

When the pans are assembled the ridge 17 bites into the rubbery layer 20 and therefore forms a good seal. The flanges while being compressed together are secured by clips or other external holding devices.

In another arrangement, not shown, the pans 11, 15 are formed of plastics material having resilient properties, one of the flanges 12,16 being formed with an integral extension which resiliently engages over the other flange to clip the two flanges together.

In this arrangement, one of the mating surfaces of the flanges has the liquid gasket applied to it, the two pans are pressed together so that the integral clip engages and no separate clipping operation is required.

While the above arrangements describe only one of the mating surfaces of the flanges being coated with the liquid gasket, it is within the invention to coat both mating surfaces. It is also within the invention to coat plane flanges (i.e. without the ridge and groove of Figure 1) or indeed any other configuration.

In the arrangement of Figures 2 and 3, another integral clipping system is shown for use with a solidified sealant. One pan 31 has a flange 32 with a channel 33 and upturned separate tabs 34 spaced around its periphery. The diaphragm 35 has a skirt 36 lying within the tabs 34. The other pan 37 has a plane flange 38 with a slightly angled periphery 39 turned away from the flange 32. The angle between the plane part and the angled part lies adjacent the channel 33, which is filled with the solidified sealant material as described above. To clip the two pans together, the tabs 34 are bent in the direction of arrow 'A' into the position shown in Figure 3. It will be seen that the tab 34 has forced the angled part 39 down to indent into the cured gasket, the whole edge of the flange 38 being resiliently deformed thereby.

In a variation of this embodiment the facing plane surface of flange 38 can also be coated with the liquid gasket material.

1. A method of making a gas-measuring unit for a dry gas meter of the kind comprising a pair of dished pans having facing flanges and a flexible diaphragm gripped between the flanges, including the step of applying a a viscous liquid of a kind which sets or cures to form a resilient, gas-resistant solid gasket directly to at least one of the facing flange surfaces in a continuous ribbon, and securing the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Sealing means This invention relates to a method of providing a gas-tight seal in a gas-measuring unit of a dry gas meter. The invention provides a method of making a gas-measuring unit for a dry gas meter of the kind comprising a pair of dished pans having facing flanges and a flexible diaphragm gripped between the flanges, including the step of applying a viscous liquid of a kind which sets or cures to form a resilient, gas-resistant solid gasket directly to at least one of the facing flange surfaces in a continuous ribbon, and securing the facing flanges together with the diaphragm therebetween. Said method of applying the liquid may be by rolling or brushing or dipping or spraying or by gun application. The dished pans may be secured together either after or before the liquid is fully cured or set. The pans may be secured together by separate clips. Alternatively, one pan may have an integral clip means which resiliently engages over the other, for instance by bent-over tabs. The invention also extends to a dry gas meter when formed by the method referred to above. Specific embodiments of the invention are shown in the accompanying drawings, in which: Figure 1 is a diagrammatic scrap representation of part of a double-chamber unit for a gas meter, and Figures 2 and 3 are diagrammatic scrap representations of a different double-chamber unit for a gas meter. Gas-measuring units for dry gas meters, for instance as described in Patent No. 1,165,151, comprise a pair of dished steel pans secured together about their edges, with a flexible diaphragm dividing one pan from the other. As shown in Figure 1, one of the dished pans 11 has a flange 12 running around its periphery with a groove 13 in the flange. The other pan 15 also has a flange 16, but this flange has a ridge 17 running around it, the ridge 17 being located and of a size to seat in the groove 13. A flexible diaphragm 18 of synthetic rubber extends across the pans, between the flanges 12, 16, and has a depending skirt 19 around its periphery serving to locate it relative to the pans. A problem with this type of dished pan is that the flanges are frequently not flat and so to obtain a gas-tight seal it is usual to mould a rubber gasket to the periphery of the synthetic diaphragm. Such a process is difficult and costly and results in high reject levels. The sealing problem is solved according to this invention by forming a gasket from a liquid which is disposed directly onto a flange, thereby enabling the peripheral gasket of the diaphragm to be omitted. The liquid may be any viscous liquid which is sufficiently viscous to stay in place on the flange and which sets or cures to a resilient solid and which is gas resistant. For instance, room temperature vulcanizing silicon rubbers, either cured by reaction with air or by mixing two components, may be used.Alternatively, polysulphides or polyurethanes are suitable, as are hot-melt applied sealants which set as they cool. The liquid is applied to the flange 12 in a continuous ribbon by rolling or brushing or spraying or by gun application to form a layer 20. The layer 20 may be at a minimum to just fill the groove 13 or may, as shown, have a thickness of up to 1 mm on the surface of the flange. The layer 20 may be left to set before the pans are assembled, but alternatively may be assembled when still semi-fluid. When the pans are assembled the ridge 17 bites into the rubbery layer 20 and therefore forms a good seal. The flanges while being compressed together are secured by clips or other external holding devices. In another arrangement, not shown, the pans 11, 15 are formed of plastics material having resilient properties, one of the flanges 12,16 being formed with an integral extension which resiliently engages over the other flange to clip the two flanges together. In this arrangement, one of the mating surfaces of the flanges has the liquid gasket applied to it, the two pans are pressed together so that the integral clip engages and no separate clipping operation is required. While the above arrangements describe only one of the mating surfaces of the flanges being coated with the liquid gasket, it is within the invention to coat both mating surfaces. It is also within the invention to coat plane flanges (i.e. without the ridge and groove of Figure 1) or indeed any other configuration. In the arrangement of Figures 2 and 3, another integral clipping system is shown for use with a solidified sealant. One pan 31 has a flange 32 with a channel 33 and upturned separate tabs 34 spaced around its periphery. The diaphragm 35 has a skirt 36 lying within the tabs 34. The other pan 37 has a plane flange 38 with a slightly angled periphery 39 turned away from the flange 32. The angle between the plane part and the angled part lies adjacent the channel 33, which is filled with the solidified sealant material as described above. To clip the two pans together, the tabs 34 are bent in the direction of arrow 'A' into the position shown in Figure 3. It will be seen that the tab 34 has forced the angled part 39 down to indent into the cured gasket, the whole edge of the flange 38 being resiliently deformed thereby. In a variation of this embodiment the facing plane surface of flange 38 can also be coated with the liquid gasket material. CLAIMS

1. A method of making a gas-measuring unit for a dry gas meter of the kind comprising a pair of dished pans having facing flanges and a flexible diaphragm gripped between the flanges, including the step of applying a a viscous liquid of a kind which sets or cures to form a resilient, gas-resistant solid gasket directly to at least one of the facing flange surfaces in a continuous ribbon, and securing the facing flanges together with the diaphragm therebetween.

2. A method as claimed in claim 1, wherein the step of applying the viscous liquid is performed by rolling or by brushing or by spraying or by gun application of the liquid to the flange.

3. A method as claimed in claim 1, wherein the step of applying the viscous liquid is performed by dipping the flange into the liquid.

4. A method as claimed in any of claims 1 to 3, including the step of curing the liquid either fully or partially before the facing flanges are secured together.

5. A method as claimed in any of claims 1 to 4, wherein said step of securing the facing flanges together comprises applying a plurality of separate clips thereto.

6. A method as claimed in any of claims 1 to 4, wherein said step of securing the facing flanges together comprises locating resilient clip means integral with one of the flanges adjacent the other flange and pressing the flanges together so that the clip means resiliently engages over the said other flange.

7. A method as claimed in any of claims 1 to 6, wherein said viscous liquid is a room-temperature vulcanizing silicon rubber, or a polysulphide or a polyurethane.

8. A method as claimed in any of claims 1 to 6, wherein one of said flanges has a circumpherential groove, and said step of applying the viscous liquid comprises filling said groove.

9. A method as claimed in claim 8, wherein said step of applying the viscous liquid also comprise forming a layer on the surface of the said one flange.

10. A method as claimed in claim 8 or claim 9, wherein said one flange has separate tabs and said step of securing the flanges together comprises bending the tabs over the other flange, thereby forcing said other flange into the gasket.

11. A method as claimed in claim 8 or claim 9, wherein the other of said flanges has a circumferential ridge and said step of securing the flanges together comprises pressing the ridge into the gasket formed in the groove.

12. A method of making a gas-measuring unit for a dry gas meter substantially as described herein be fore with reference to the accompanying drawings.

13. A gas-measuring unit for a dry gas meter formed by the method claimed in any of claims 1 to 12.

14. A gas-measuring unit for a dry gas meter substantially as described hereinbefore with reference to Figure 1 orto Figures 2 and 3 of the accompanying drawings.