HK1180098A - Burst indicator - Google Patents

Abstract

A burst indicator (24) for use in a rupture disc assembly (12) is provided. The burst indicator (24) comprises a non-electrically conductive material having an outer annular portion (66) and an inner section (68) joined to the outer portion by a pair of bridge features (70, 72). A circuit comprising electrically conductive segments (78, 80) is located on the burst indicator (24) and can be used to monitor the integrity of the rupture disc (20). One electrically conductive segment (78) is located on the outer annular portion (66), and another electrically conductive segment (80) extends across the bridge features (70, 72) and inner section (68). Upon rupture of the rupture disc (20), one of the bridge features (72) carrying an electrically conductive segment (80) severs thereby opening the circuit.

Description

Burst indicator

Technical Field

The present invention relates generally to burst indicators and pressure relief devices incorporating burst indicators. Specifically, the burst indicator includes at least one non-conductive film and a circuit formed from a conductive material. The burst indicator can monitor the integrity of the rupture disc when the burst indicator is positioned in close proximity to the rupture disc and signal a burst of the rupture disc when the electrical circuit is interrupted by a severing of one or more conductive segments comprising the electrical circuit.

Technical Field

In many processes and applications, rupture discs are installed in fluid passageways, such as between two ferrules or pipe flanges in overpressure relief devices. As a general example, in order to visually inspect the rupture disc, it would be necessary to remove a portion of the protected device or the associated fluid release channel. In addition, rupture discs are often installed remotely or otherwise in inaccessible locations. In such a configuration, it may be very difficult to visually inspect the rupture disc to determine its integrity.

An electronic monitoring system, such as one that includes a flow sensor and a burst indicator, provides an immediate notification in the event of rupture of the rupture disc. U.S. patent No. 5,155,471 discloses a flow sensor including a support gasket defining a flow passage and having a thin, flexible membrane extending across the gasket. The conductive strips are bonded across opposite quadrants of the film for continuous connection to the electrical indicator circuit.

4,978,947 discloses a rupturable liquid flow indicator and a rupture disc assembly including the indicator. The indicator comprises a rupturable member adapted to be clamped within the fluid flow passage having at least one opening for weakening a portion of the member. The current conductor is attached across the weakened portion of the rupturable member such that when the member ruptures due to fluid pressure exerted thereon, the conductor also ruptures.

5,631,634 discloses a pressure sensor assembly that includes a rupture disc constructed entirely of metal and having a plurality of circumferentially spaced lobes. The rupture disc is connected to a pair of leads that are connected to a warning monitor. When exposed to a rise in fluid pressure associated with a rupture disk burst or valve leak, the pressure sensor tears creating an open circuit.

Disclosure of Invention

In one embodiment according to the present invention, a burst indicator is provided that includes a non-conductive material including an outer annular portion and an inner portion coupled to the outer annular portion by first and second bridge features. The burst indicator also includes an electrical circuit including first and second electrically conductive segments. The first conductive segment is located on the outer annular portion. The second conductive segment extends from the outer annular portion, through the first bridge feature to the inner portion, and then back through the second bridge feature to the outer annular portion where it is connected to the first conductive segment.

In another embodiment according to the present invention, a burst indicator is provided that includes a non-conductive material including an outer annular portion, an inner portion, and at least two apertures disposed between the outer annular portion and the inner portion. The holes are separated from each other by at least first and second bridge features. The burst indicator also includes an electrical circuit including at least first and second electrically conductive segments. The first conductive segment is located on the outer annular portion. The second conductive segment extends through the inner portion and is coupled to the first conductive segment at the location of the outer annular portion.

In yet another embodiment according to the present invention, a rupture disc assembly is provided that includes a rupture disc having a central rupturable portion and a burst indicator signaling rupture of the central rupturable portion. The burst indicator comprises a non-conductive material including an outer annular portion and an inner portion coupled to the outer annular portion by at least first and second bridge features. The burst indicator also includes an electrical circuit including at least first and second electrically conductive segments. The first conductive segment is located on the outer annular portion and the second conductive segment extends from the outer annular portion, through the first bridge feature to the inner portion, then through the second bridge feature to the outer annular portion, and connects with the first conductive segment at the outer annular portion to form a circuit.

In another embodiment according to the present invention, a method of monitoring the condition of a rupture disc positioned within a fluid passage is presented. A burst indicator is provided having a non-conductive material having an outer annular portion and an inner portion coupled to the outer annular portion by at least first and second bridge features. The burst indicator further includes an electrical circuit including at least first and second electrically conductive segments coupled together to form an electrical circuit. The first conductive segment is located on the outer annular portion and the second conductive segment extends from the outer annular portion, through the first bridge feature to the inner portion, then through the second bridge feature to the outer annular portion, and connects with the first conductive segment at the outer annular portion. The burst indicator is positioned within the fluid passage such that actuation of the rupture disc in response to the presence of a sufficient pressure condition within the fluid passage causes at least one of the first and second bridge features to tear, thereby severing the second conductive segment and opening the circuit.

Drawings

FIG. 1 is a perspective view of a pressure relief assembly including a rupture disc and a burst indicator in accordance with one embodiment of the present invention;

FIG. 2 is a cross-sectional view of the pressure relief assembly of FIG. 1;

FIG. 3 is an exploded view of the pressure relief assembly of FIG. 1;

fig. 4 is an exploded view of a rupture disc assembly including a burst indicator made in accordance with the present invention;

FIG. 5 is a plan view of a burst indicator made in accordance with the present invention;

FIG. 6 is a cross-sectional view of the burst indicator taken along line 6-6 of FIG. 5; and

fig. 7 is an enlarged perspective view of the severable bridge feature of the burst indicator of fig. 5.

Detailed Description

The following description illustrates certain embodiments of the invention, but any part thereof should not be construed as limiting the overall scope of the invention. Turning to fig. 1, a pressure relief assembly 10 according to one embodiment of the present invention is shown. Assembly 10 generally includes a rupture disc assembly 12 interposed between a pair of ferrules 14, 16. Rupture disc assembly 12 is held between ferrules 14, 16 by a clamp 18.

When the rupture disc assembly 12 is installed in the pressure relief assembly 10, the rupture disc assembly 12 is substantially hidden from view of the operator. Thus, in some applications it is desirable to use sensors to monitor the integrity of the rupture disc assembly 12 and to alert the operator if the rupture disc assembly fails to allow communication between the ferrule holes 17, 19. In certain rupture disc assembly embodiments, the sensor is positioned in close proximity to the actual rupture disc, for example between ferrules 14, 16. However, care must be taken when inserting additional structures between the ferrules, as these structures may create stress zones on the rupture disc secured between the ferrules that may affect the burst characteristics of the rupture disc.

It has been found that a "strip" burst indicator, as disclosed in U.S. patent No. 4,342,988, when secured with rupture disc assembly 12 between ferrules 14, 16, affects the burst characteristics of some rupture discs to an unacceptable degree, even at the lower end of the burst pressure range for a particular rupture disc of a particular thickness. In theory, when a strip-like burst indicator is sandwiched between ferrules 14, 16, it has the effect of creating a discontinuous area where the increased thickness creates a stress zone in the outer annular region of the rupture disc, thereby altering the rupture characteristics of the rupture disc, typically by reducing the burst pressure. This effect is expected to be more pronounced at the upper end of the burst pressure range for a given rupture disc thickness. As described below, the burst indicator according to the present invention addresses this problem by providing a degree of uniformity in the area contacted by the ferrule.

As shown in fig. 2-4, rupture disc assembly 12 includes a rupture disc 20, a support member 22, and a burst indicator 24 disposed within a gasket 26. Gasket 26 includes layers 28, 30 and a central aperture 34, with layers 28, 30 being connected by a circumferential sidewall 32. A slit 36 is formed in a portion of the sidewall 32 to allow insertion of the rupture disc 20, support member 22 and burst indicator 24 between the layers 28, 30. Each layer 28, 30 of the gasket 26 includes a generally circular O-ring 38, 40 and an inboard flange portion 42, 44, respectively.

As shown, rupture disc 20 comprises a reverse-acting rupture disc having an indented (i.e., convex or arcuate) central rupturable portion 46. However, it is within the scope of the invention to use a positive acting convex rupture disc and a non-convex or flat rupture disc. Exemplary rupture discs for use in accordance with the present invention are described in U.S. patent No. 6,945,420, which is incorporated herein by reference in its entirety.

As shown in fig. 4, support member 22 includes an annular inner center 48, an outer peripheral portion 50 radially spaced from inner center 48, and one or more connecting portions 52 extending between inner center 48 and outer peripheral portion 50. The connecting portion 52 cooperates with the outer peripheral portion inner edge 54 and the inner central outer edge 56 to define one or more apertures 58 in the support member 22. Support member 22, and in particular inner core 48, optionally includes inwardly extending tabs 60 and teeth 62. Tongue 60 extends into support member central aperture 64 and is configured to prevent rupture disc 20 from breaking during rupture. The illustrated support member is described in further detail in U.S. patent application No. 12/422,851, filed on 13/4/2009, the entire contents of which are incorporated herein by reference. Other support members, such as a relatively flat annular support ring (i.e., without the aperture 58), may be used in place of the support member 22.

Fig. 5 illustrates one embodiment of a burst indicator 24 according to the present invention. The burst indicator 24 includes an outer annular portion 66 and an inner portion 68. Annular portion 66 and inner portion 68 are coupled together by first and second bridge features 70, 72, respectively. The outer annular portion 66 and the inner portion 68 are also isolated from each other by arcuate apertures 74, 76.

Conductive segments 78, 80 form an electrical circuit that can be used to monitor the integrity of the burst indicator and, therefore, the operational status of rupture disc 20. In certain embodiments, segment 78 is located entirely on outer annular portion 66 and extends substantially along the entire circumference of portion 66, except for a very small void region 82, which void region 82 is defined by first segment end regions 84, 86. In these embodiments, the segment 78 does not extend through any portion of the inner portion 68. Segment 80 extends from outer annular portion 66, specifically through void region 82, through bridge feature 70, and then to inner portion 68. At about the center of the inner portion 68, the direction of the segment 80 changes and then extends through the bridge feature 72 back to the outer annular portion 66. As shown, the segment 80 direction is changed by approximately 60 degrees, although in other embodiments this angle may be greater or lesser. In other embodiments, the segment 80 need not change direction at all but continues along a straight path through the inner portion 68. To accommodate the path of segment 80, the orientation of bridge feature 72 is also changed. Segment 80 and segment 78 are coupled together at coupling point 88 to form an electrical circuit, where coupling point 88 is located near the outer periphery of outer annular portion 66.

The outer annular portion 66 and the inner portion 68 generally comprise a non-conductive membrane. In one embodiment, the membrane is a laminated structure comprising at least two synthetic resin membrane materials (e.g., having the trade name ofAvailable polyimide film) layer. In certain embodiments, as particularly shown in fig. 6, the burst indicator 24 includes outer synthetic resin film layers 90, 92, two intermediate adhesive (e.g., acrylic-based adhesive) layers 94, 96, and a central conductive layer 98 forming the segments 78, 80. The central conductive layer 98 may comprise any suitable conductive material, such as copper or silver, or copper and silver as discussed in detail below. It is noted that burst indicators 24 having other configurations are within the scope of the present invention, such as a monolithic film applied or printed with a conductive layer.

Conductive segment 78 includes an arcuate segment 100 that extends from attachment point 88 to end region 86. Segment 100 does not form part of the circuit, but rather provides some degree of thickness uniformity, and therefore structural load uniformity, to the outer periphery of outer annular portion 66. Without segment 100, the thickness of outer annular portion 66 in this region would be different than the thickness of outer annular portion 66 in the region of segment 78. When inserted and sandwiched between ferrules 14, 16, the irregularities in thickness can create stress zones in rupture disc 20 to alter the rupture disc's rupture characteristics. By providing segment 100, the creation of stress regions is avoided, although segment 100 does not form part of the circuit. The impact of the void regions 82 on structural loading is mitigated as the segments 80 extend through the void regions 82 leaving only a minor area unoccupied by the conductive material. In certain embodiments, the length of the segments 78 is at least about 90% of the outer circumference of the outer annular portion 66. In other embodiments, the length is at least about 95% of the outer circumference of the outer annular portion 66.

At least one of the bridge features 70, 72 may include a weakened area that assists and/or defines a starting point for tearing of the bridge feature. In certain embodiments, each bridge feature separates from outer annular portion 66 when the rupture disc is ruptured. In an alternative embodiment, the bridge feature may be separate from the inner portion 68 and remain attached to the outer annular portion 66. In other embodiments, the bridge feature may tear at some point between the outer annular portion 66 and the inner portion 68.

It can be observed that when torque is applied to the bridge feature providing the initiation crack, a flat, burst indicator circuit is formed due to increased stress concentration at the ends of the crackThe adhesive and the metallic conductive material are more easily torn. Torque may be achieved in a number of ways. In one embodiment, the inclusion of angles in segment 80 places bridge feature 72 off-center with respect to the open central rupturable portion (flap) of a single-flap hinged rupture disc. In another embodiment, the bridge features 70, 72 may or may not be coaxially aligned with each other, and the entire central portion of the burst indicator 24 may be positioned off-center with respect to the centerline or line of symmetry of the central rupturable portion 46 of the single-lobed hinged rupture disc 20. In another embodiment, the central portion of the burst indicator 24 is centered with respect to the center point of the rupturable portion 46 and the bridge features 70, 72 are angled with respect to the line of symmetry of the rupture disc, while the bridge features 70, 72 may or may not be coaxially aligned with each other.

Regardless of the configuration, in these embodiments, as the petals transmit force to the inner portion 68 of the burst indicator, the desired torque is transmitted to the bridge feature 72 and stress is concentrated at the ends of the crack 102, facilitating the opening of the circuit. In one embodiment, only one weakened area is included for initiating separation, as shown at bridge feature 72 in FIG. 7. Eliminating the additional weakened area has the effect of concentrating the stress and energy at a single point rather than two or more points, thus resulting in enhanced performance during separation. As shown in fig. 7, bridge feature 72 includes a slit 102, slit 102 having an open end in communication with aperture 76. When rupture disc 20 is ruptured, central rupturable portion 46 contacts inner portion 68 and exerts stress on bridge features 70, 72. As shown in the figure, the bridge feature 72 is generally narrower than the bridge feature 70 and offset (offset) from the bridge feature 70. The slits 102 serve to further weaken the bridge feature 72, concentrating stress at the ends of the slits 102 so that it will more easily separate from the outer annular portion 66 to sever the segments 80 and open the circuit. When the bridge feature 72 is separated, the inner portion 68 can pivot about the bridge feature 70, which acts as a hinge. Thus, due to the bridge feature 70, the inner portion 68 does not fragment and remains attached to the outer annular portion 66.

Note that slits 102 are angled inwardly toward inner portion 68, as shown in fig. 7. This slight angle optimizes the tear direction through the metallic conductive segments. The copper material has in particular a much higher rupture strength and energy than the non-conductive material. Due to this difference, the path of material separation tends to change direction at the edges of the copper segment. Ideally, the path will travel the shortest distance through the copper, thus using the least energy to achieve circuit separation. When the path reaches the edge of the metal segment, it tends to change direction away from the lobe. Thus, prior to that point, the optimal path of separation is to angle inward toward the petals.

In one embodiment in accordance with the invention, conductive segment 80 may comprise primarily copper, except that at least a portion of segment 80, specifically the portion extending through bridge 72, comprises silver. Silver, especially silver, when printed as ink, has a lower tear resistance than copper. Thus, in certain embodiments, it may be desirable to form the severable portion of the segment 80 with silver.

As shown in fig. 4, in one embodiment, the burst indicator 24 may be assembled with the support member 22 and rupture disc 20 to form an integral unit that is placed within the washer 26. When placed within the washer 26, the burst indicator 24 is positioned downstream of the rupture disc 20 and the support member 22 is located between the burst indicator 24 and the rupture disc 20. The gasket central aperture 34 is aligned with the central rupturable portion 46 and the inner portion 68. In certain embodiments, rupture disc 20 is a reverse-acting rupture disc having a rupturable portion 46 having an indentation. The burst indicator may be located adjacent rupture disc 20 and separated from rupture disc 20 by support member 22 in facing relation to the concave side of rupturable portion 46. It is also within the scope of the present invention to remove support member 22 from the rupture disc assembly such that outer annular portion 66 is in direct face-to-face contact with rupture disc outer annular portion 47. If a positive acting rupture disc is used, the burst indicator 24 may need to be positioned further downstream of the rupture disc, or configured to have a convex shape, so that the inner portion 68 generally conforms to the convex surface of the positive acting rupture disc, but does not contact it until the convex portion of the rupture disc ruptures. By providing these components as an integral assembly, installation errors and the resulting operational failures may be reduced.

In certain embodiments, the burst indicator 24 is provided with a tab 104, the tab 104 including electrically conductive leads 106, 108 coupled to the electrically conductive segments 78, 80, respectively. The connector 104 can then be operably connected to a patch plug 110 (as shown in fig. 1) or other similar structure so that the burst indicator circuit can be integrated with a larger monitoring system. The joint 104 also tends to be configured similarly to the support member joint 112 so that the two joints can be mated for installation. As shown in fig. 4, rupture disc 20 may also be provided with a joint 114, although, in this embodiment, joint 114 is not as long as either of joints 104 and 112. However, the primary function of the tabs 112 is to assist, ensure and visually indicate proper installation of the correct rupture disc assembly 12 within a given pressure relief assembly 10.

It is also within the scope of the present invention to use burst indicator 24 in applications that do not utilize ferrules 14, 16, such as where a rupture disc assembly is bolted between pipe flanges at the end of adjacent portions of a fluid conduit, or assembled within a rupture disc holder that is then bolted between pipe flanges at the end of adjacent portions of a fluid conduit. While such "bolted" applications differ from those with ferrules 14, 16, particularly in the removal of softer gasket material adjacent the rupture disc and the use of greater clamping force upon installation, the advantages described above still apply.

The present invention also provides a method of monitoring the condition of rupture disc 20 by providing a burst indicator 24 according to any of the embodiments described above and by positioning the burst indicator adjacent the rupture disc. Burst indicator 24 is operably connectable to a monitoring system configured to alert an operator to a change in the integrity of the rupture disc. When rupture disc 20 is ruptured, as described above, rupturable portion 46 physically contacts inner portion 68 and causes bridge feature 72 to separate from outer annular portion 66 thereby severing conductive segment 80 and opening the circuit. The opening of the circuit causes the monitoring system to alert the operator that rupture disc 20 has ruptured.

Claims (41)

1. A burst indicator comprising:

a non-conductive material having an outer annular portion and an inner portion coupled to the outer annular portion by at least a first bridge feature and a second bridge feature; and

a circuit comprising at least a first conductive segment on the outer annular portion and a second conductive segment extending from the outer annular portion, through the first bridge feature to the inner portion, then through the second bridge feature to the outer annular portion, where it connects with the first conductive segment.

2. The burst indicator of claim 1 wherein the outer annular portion and the inner portion comprise a non-conductive film.

3. The burst indicator of claim 2 wherein the membrane is a laminated structure comprising at least two layers of synthetic resin membrane material.

4. The burst indicator of claim 3 wherein the synthetic resin film material is a polyimide film.

5. The burst indicator of claim 3 wherein the first conductive segment and the second conductive segment are positioned between the at least two layers of synthetic resin film material.

6. The burst indicator of claim 1 wherein the first conductive segment is located near an outer circumference of the outer annular portion and has a length that is at least about 90% of the outer circumference of the outer annular portion.

7. The burst indicator of claim 1 wherein the first conductive segment extends circumferentially along the outer annular portion and is defined by a spaced pair of end regions between which the second conductive segment extends toward the first bridge feature.

8. The burst indicator of claim 1 wherein the second bridge feature is offset from the first bridge feature.

9. The burst indicator of claim 1, wherein the second bridge feature is configured to tear resulting in severing of the second conductive segment.

10. The burst indicator of claim 9 wherein the second bridge feature comprises a weakened area that facilitates tearing of the second bridge feature and severing of the second conductive segment.

11. The burst indicator of claim 10 wherein the weakened area comprises a crack formed in the second bridge feature.

12. The burst indicator of claim 1 wherein the first conductive segment comprises an arcuate segment that does not form part of the electrical circuit.

13. The burst indicator of claim 1 wherein the burst indicator further comprises an elongated tab on which leads for the first and second conductive segments are located.

14. The burst indicator of claim 1, wherein at least a portion of the second conductive segment extending through the second bridge feature comprises silver or silver ink.

15. The burst indicator of claim 14, wherein the remainder of the circuit comprises copper.

16. The burst indicator of claim 1, wherein at least a portion of the electrical circuit comprises copper.

17. A burst indicator comprising:

a non-conductive material comprising an outer annular portion, an inner portion, and at least two apertures disposed between the outer annular portion and the inner portion, the at least two apertures separated from one another by at least a first bridge feature and a second bridge feature; and

an electrical circuit comprising at least a first conductive segment on the outer annular portion and a second conductive segment extending through the inner portion, the second conductive segment being coupled with the first conductive segment at a location on the outer annular portion.

18. The burst indicator of claim 17 wherein the outer annular portion and the inner portion comprise a non-conductive film.

19. The burst indicator of claim 18 wherein the membrane is a laminated structure comprising at least two layers of synthetic resin membrane material.

20. The burst indicator of claim 19 wherein the first conductive segment and the second conductive segment are positioned between the at least two layers of synthetic resin film material.

21. The burst indicator of claim 17, wherein the second bridge feature is configured to tear resulting in severing of the second conductive segment.

22. The burst indicator of claim 21, wherein the first bridge feature is configured to remain connected to the outer annular portion and the inner portion after the second bridge feature tears.

23. The burst indicator of claim 21 wherein the second bridge feature comprises a weakened area that facilitates tearing of the second bridge feature and severing of the second conductive segment.

24. The burst indicator of claim 23 wherein the weakened area comprises a slit having an open end in communication with one of the arcuate apertures.

25. The burst indicator of claim 17, wherein at least a portion of the second conductive segment extending through the second bridge feature comprises silver or silver ink.

26. The burst indicator of claim 25, wherein the remainder of the circuit comprises copper.

27. The burst indicator of claim 17, wherein at least a portion of the electrical circuit comprises copper.

28. A rupture disc assembly, comprising:

a rupture disc having a central rupturable portion; and

a burst indicator for signaling rupture of the central rupturable portion, the burst indicator comprising:

a non-conductive material comprising an outer annular portion and an inner portion coupled to the outer annular portion by at least a first bridge feature and a second bridge feature, an

A circuit comprising at least a first conductive segment on the outer annular portion and a second conductive segment extending from the outer annular portion, through the first bridge feature to the inner portion, then through the second bridge feature to the outer annular portion, where it connects with the first conductive segment.

29. The rupture disk assembly of claim 28, wherein the rupture disk assembly further comprises a support member interposed between the rupture disk and the burst indicator.

30. The rupture disc assembly of claim 29, wherein the rupture disc, the support member and the burst indicator are positioned between adjacent layers of a resilient washer, each layer of the resilient washer having a central aperture aligned with the central rupturable portion of the rupture disc.

31. The rupture disc assembly of claim 28, wherein the outer annular portion and the inner portion comprise a non-conductive membrane.

32. The rupture disc assembly of claim 31, wherein the film is a laminate structure comprising at least two layers of synthetic resin film material.

33. The rupture disc assembly as set forth in claim 32, wherein said first conductive segment and said second conductive segment are positioned between said at least two layers of synthetic resin film material.

34. The rupture disc assembly as set forth in claim 28, wherein said first conductive segment does not extend through said inner portion.

35. The burst indicator of claim 28 wherein the first conductive segment extends circumferentially along the outer annular portion and is defined by a spaced pair of end regions between which the second conductive segment extends toward the first bridge feature.

36. The rupture disc assembly of claim 28, wherein the burst indicator further comprises at least two arcuate apertures disposed between the outer annular portion and the inner portion, the arcuate apertures being separated from one another by the first and second bridge features;

37. the rupture disc assembly of claim 28, wherein the second bridge feature is configured to tear resulting in severing of the second conductive segment.

38. A method of monitoring the status of a rupture disc positioned within a fluid passageway, the method comprising:

providing a burst indicator, the burst indicator comprising: a non-conductive material comprising an outer annular portion and an inner portion coupled to the outer annular portion by at least a first bridge feature and a second bridge feature; and a circuit comprising at least a first conductive segment on the outer annular portion and a second conductive segment extending from the outer annular portion, through the first bridge feature to the inner portion, then through the second bridge feature to the outer annular portion, connecting with the first conductive segment at the outer annular portion; and

positioning the burst indicator within the fluid passage such that action of the rupture disc in response to the presence of a sufficient pressure condition within the fluid passage causes at least one of the first and second bridge features to tear, thereby severing the second conductive segment and opening the electrical circuit.

39. The method of claim 38, wherein the burst indicator is positioned such that upon rupture of the rupture disc, the rupturable portion of the rupture disc physically contacts the inner portion and causes at least one of the first bridge feature and the second bridge feature to tear.

40. The method of claim 38, wherein said rupture disc is a reverse-acting rupture disc having a concavo-convex rupturable portion, said burst indicator being positioned adjacent said rupture disc in facing relationship to a concave side of said rupturable portion.

41. The method of claim 38, wherein at least one bridge feature comprises a weakened area that facilitates tearing of the at least one bridge feature.