TECHNICAL FIELD This disclosure relates to dust collectors used, for example, to purify air from industrial processing. In particular, this disclosure concerns the provision of arrangements and methods to detect explosions in dust collectors.

BACKGROUND Dust collectors are used in a variety of applications. One environment of use is in an industrial setting for air purification. Such dust collectors can use filter bags in bag houses. Dust collectors of this type are described in, for example, U. S. Patent No. 5,931, 988; 3,475, 884; 5,853, 442; and 5,928, 395. In addition, dust collectors may be in the form of : tubular, pleated filter elements such as that shown in U. S.

Patent No. 4,395, 269; or UMA Unicell Dalamatic Sintamatic and/or cartridge collectors.

Dust collectors could handle expolsive dust, which with a suitable ignition source, can lead to an explosion. A classical way of preventing the expolsion pressure is to install an explosion vent. An expolsion vent directs the pressure and flames to a safe area.

SUMMARY A method for detecting an explosion in a dust collector includes providing a dust collector having an explosion vent and a membrane covering the explosion vent. A first member is oriented in extension across the membrane. A circuit path is formed with the first member, and a detection system is triggered upon breakage of the circuit path upon explosion within the dust collector.

A dust collector arrangement is provided including a dust collector having a dust flow inlet, a clean air outlet, and an explosion vent. A membrane covers the explosion vent, with a first member being provided in extension across the membrane. The member is constructed and arranged to break upon breakage of the membrane. A detection system is provided that is responsive to breakage of the member.

A kit for use with a dust collector having an explosion vent includes a panel with a flexible membrane mountable thereon ; a frame constructed and arranged to be mounted around the panel; a bar including a first section and a second section; a collar connecting together the first section and the second section; and a plurality of switches mountable to the frame and being constructed and arranged to receive opposite ends of the bar.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of a dust collector system in an environment of use; FIG. 2 is an exploded, perspective view of an explosion vent, panel arrangement, and explosion detection system utilized with the dust collector of FIG. 1; FIG. 3 is a front elevation view of the panel arrangement and explosion detection system shown in FIG. 2; FIG. 4 is a schematic, side elevational view of the arrangement shown in FIG. 3; FIG. 5 is an enlarged, schematic, side elevational view of the arrangement shown in FIG. 3, and showing an expanded membrane; FIG. 6 is a schematic, enlarged, side elevational view of the arrangement shown in FIGS. 3-5, after an explosion has occurred; FIG. 7 is a schematic, enlarged, top plan view of one embodiment of a member utilized in the explosion detection system of FIGS. 1-6 ; FIG. 8 is an enlarged, fragmented view showing the connection between the member and the frame in FIGS. 2-5; FIG. 9 is an enlarged, schematic, top plan view of an alternate embodiment of a member useable in the explosion detection system of FIGS. 1-6 ;

FIG. 10 is a schematic, front elevational view of an alternate embodiment of an explosion vent, panel, and explosion detection system; and FIG. 11 is a schematic, side elevational view of the arrangement shown in FIG. 10.

DETAILED DESCRIPTION A. Dust Collector Systems; Environment of Use FIG. 1 illustrates one example environment of use for a dust collector generally at 20. A dust collector 22 is mounted, typically outside of a factory wall 24 with ducting 26 extending between the dust collector 22 and a collection arrangement 28 inside of the factory wall 24. The collection arrangement 28, in the embodiment shown, includes an inlet hood 30 that draws dirty air 32 therein. The dirty air 32 is typically drawn through the hood 30 and through the ducting 26 into the dust collector 22 by way of a fan arrangement 34.

When the dust collector 22 is installed inside of a building (as opposed to outside--installation on the outside being the view shown in FIG. 1), an explosion vent used in connection with it should be ducted to a safe area (typically, outside of the building) through a short venting duct, sometimes referred to as a"blow off channel. " Returning again to FIG. 1, the dirty air is drawn through the dust collector 22 and through a series of filters therein. The dirt is channeled into a hopper 36, and the purified air is directed through an outlet 38 and into the environment at 40.

The filters in the dust collector may be a variety of filter types. These include bag houses such as those described in U. S. Patent Nos. 5,931, 988; 3,475, 884; 5,853, 442; and 5,928, 395, incorporated herein by reference; or tubular, pleated filters such as U. S. Patent No. 4,395, 269, incorporated herein by reference; or UMA Unicell Dalmatic Sintamatic and/or cartridge collectors.

An explosion vent is shown in this embodiment along the side of the dust collector 22. In some embodiments, the explosion vent can be on different sides of the dust collector 22, including the top. The explosion vent 42 allows for the release of pressure within the dust collector 22 in the event of an explosion within the dust collector 22. As explained above, ignition sources may not always be prevented.

When this happens, a spark may cause an explosion. The explosion vent 42 allows for the release of pressure and front flames within the collector 22 due to the

explosion. Without the explosion vent 42, the entire collector 22 could explode and cause considerable damage due to flying debris and shrapnel. When an explosion occurs in a dust collector 22, the operators of the system 20 should be notified.

Several actions should be automatically initiated to limit the risks and minimize dangerous consequences.

B. FIGS. 2-11; Explosion Detection System FIG. 2 illustrates a schematic, perspective view of a panel arrangement and explosion detecting system generally at 50. The arrangement 50 is used to cover the explosion vent 42 of the dust collector 22. In the embodiment shown, the arrangement 50 includes a panel 52 comprising a grid 54. Covering the grid 54 is a flexible membrane 56, which in the embodiment of FIGS. 2 and 3, is transparent. A frame 58 circumscribes, surrounds, and holds the panel 52 and membrane 56 in place in covering relation to the explosion vent 42.

Also shown in FIG. 2 is an explosion detection arrangement 60. In the embodiment shown, the explosion detection arrangement 60 includes a frame 62 adapted to be secureable to the frame 58. The frame 62 defines an open aperture 64.

Extending across the aperture 64 between opposite sides 65, 66 of the frame 62 is a detection member 68.

In the embodiment shown, the detection member 68 is connected to the frame 62 by way of a pair of brackets 70,71. The brackets 70,71 contain components for forming a circuit path with the detection member 68. This is explained more below.

For the particular embodiment illustrated, the detection member 68 includes a first section 74 and a second section 76. The first and second sections 74,76 are joined together at respective ends with a coupling or collar 78. More details on these components are described further below.

Before more of the system details in the illustrated embodiment are described, a general overview of operation is explained. FIGS. 3 and 4 show the panel and explosion detection system 50 in front elevation and side elevational views. During normal operation of the dust collector 22, FIGS. 3 and 4 would be typical representations of the appearance of the arrangement 50. In FIG. 5, the membrane 56 is shown expanding due to the build up of pressure within the dust collector 22. The build up of pressure may be due to, for example, an explosion

within the dust collector 22. If an explosion occurs, the membrane breaks. This is shown in FIGS. 6. Upon breakage of the membrane 56, the detection member 68 breaks apart at the collar 78, and the first and second sections 74,76 are caused to be moved from the supporting brackets 70,71. When this happens, the circuit path is broken and the system operators are notified. Dust 80 can be seen being released from the vent 42.

With that overview in mind, we now turn to details of the arrangement shown in the particular embodiment illustrated. FIG. 7 shows a top plan view of the detection member 68. In this embodiment, the detection member 68 forms a bar 82 with opposite ends 83,84. Each of the ends 83,84 is secured within a respective bracket 70,71. The collar 78 is shown connecting the first section 74 and the second section 76 together to form the bar 82. The collar 78, in the embodiment shown, includes an open, elongated slot 86. This allows for disassembly of the bar 82 upon explosion to allow each of the ends 83,84 to become disengaged from their respective brackets 70,71.

At each of the ends 83,84, there is a slot 88,89 defined. The slots 88,89 are for engagement with switches 90,91 (FIG. 3) supported by respective brackets 70, 71. The switches 90,91 can be limit switches, when used with the embodiment of FIG. 7, or other types of switches when used with other embodiments.

An alternate embodiment of the detection member 68 is shown in FIG. 9 at 68'. For the detection member 68', there is also first and second sections 74', 76' connected together by a collar 78'. In this embodiment, however, the opposite ends 83', 84'are not slotted. Instead, each of the first section 74'and second section 76' holds or contains therewithin magnets 93,94. The magnets 93,94 enable a circuit path when mounted in the brackets 70,71 by way of switches 90, 91. In this embodiment, the switches 90,91 are magnetic proximity switches. The magnets 93, 94 should be mounted in a portion of the bar 68'such that they will be in close proximity with the magnetic switches in the brackets 70,71, thereby closing the circuit. In the embodiment shown in FIG. 9, the magnets 93,94 are mounted adjacent to the ends 83', 84'.

The embodiment of FIGS. 2-6 utilizes, in the embodiment illustrated, a single detection member 68. It has been found that this arrangement is useful for sizes of the panel 52 that are greater than a certain area. For panels 52 that are less than a certain area, for example less than 0.3 square meters, the aid of a cutting

device can be useful to encourage the membrane 56 to rupture. In the types of systems that use a cutting device, it may be useful to have more than one detection member 68. An example of such an embodiment is shown in FIGS. 10 and 11.

FIG. 10 shows a side elevational view of a panel and explosion detection system 100 that is analogous to the system 50 of FIGS. 2-6. As such, there is a panel 102, a grid 104, a membrane 106, a frame 108, and a second frame 110.

A cutting member, in this example, a serrated saw or knife 112 is shown in extension across the membrane 106. When the membrane 106 expands due to the build up of pressure within the dust collector 22, due to an explosion, for example, the knife 112 penetrates the membrane 106 to rupture the membrane 106 in order to relieve the pressure within the dust collector 22.

The explosion detection system 60 is shown, and in this embodiment, includes a pair of detection members 114,116. Each of the detection members 114, 116, in the preferred embodiment, is constructed identically to the detection member 68. As such, each of the detection members 114,116 includes a first section 118, 119, a second section 120, 121, and a collar 122,123. The detection members 114, 116 are mounted in brackets 125,126 secured to the frame 110. In the preferred embodiment illustrated, the detection members 114,116 are mounted parallel to each other and parallel to the knife 112, with the knife 112 separating the detection member 114 from the detection member 116.

Each of the brackets 125, 126 holds a pair of switches 128,129, 130, 131.

The switches 128-131 can be, as explained above, either limit switches, magnetic proximity switches, or other suitable components.

When an explosion occurs within the dust collector 22, the membrane 106 expands in the direction toward the knife 112. The knife 112 penetrates the membrane 106 to allow for the escape of pressure and dust 80. The explosion will cause at least one of the detection members 114 and 116 to break, causing the respective first sections 118,119 and second sections 120,121 to move from the brackets 125,126. This will cause a breakage in the circuit path and trigger the detection system. Both members 114,116 may be broken in an explosion. For operation, however, it is only necessary for at least one of the detection members 114,116 to break.

Upon breakage of the circuit path in the embodiment of FIGS. 2-6 or in the embodiments of FIGS. 10-11 will involve shutting down of the main operation of

the dust collector 22. In some systems, there may also be an alarm triggered to alert the system operator that an explosion has occurred and the dust collector 22 has shut down.

FIG. 2 also shows a kit 134 that can be used to retrofit a dust collector 22.

The kit 134 typically will include the panel 52, the flexible membrane 56 to be mounted on the panel 52, the frame 62 to be mounted around the panel 52, the detection member 68, and a plurality of switches 90,91. The detection member 68 will typically include first and second sections 74,76 joinable together by collar 78.

The system 60 is useful such that, in the event of an explosion rupturing the panel, the explosion is detected and the dust is isolated. Once the explosion occurs, there is no automatic re-setting. Further, the detection system 60 does not interfere with the bursting of the membrane 56,106. The detection system 60 is sufficiently distant from the membrane so that it is not triggered by movements of the panel 56, 106 during off-line cleaning. Further, the detection member 68 is operable in a variety of configurations, such as vertical or horizontal.

C. Example Materials The detection member 68 can be made of a variety of materials. One example is unplasticized PVC round, rigid conduit. One useful dimension is a nominal size of about 20 mm. having an insulation resistance of 100 mega ohms.

The membrane is an expandable material that will rupture upon the appropriate pressure level. One useful material is PTFE (polytetrafluoroethylene).

In many useful embodiments, the detection member 68,114 is mounted a distance between a central longitudinal axis of the detection member 68,114 to the membrane 56,106 of at least 20 mm. , and no greater than 100 mm. For the embodiment of FIGS. 2-6, the distance between the longitudinal axis of the detection member 68 and the membrane 56 is typically 50-70 mm. For the embodiments of FIGS. 10 and 11, this distance is about 20-40 mm.

D. Experimental Testing was done with the following results. In Table 1, the tests were performed on a design of the type shown in FIGS. 2-6 (no knife installed). In Table 2 tests were done in the embodiment of the type of FIGS. 10 and 11 (with a knife).

Table 1 Panel Size (mm) Bursting Pressure (K Pa) Comment 1680 x 850 6 858 x 880 12 740 x 720 8 Table 2 Panel Size (mm.) Bursting Pressure (K Pa) Comment 552 x 349 10.7 552 x 349 4.3 Knife tip 2-3 mm. from membrane 552 x 349 11.4 Knife tip 35 mm. from membrane 552 x 349 7.6 Knife tip 20 mm. from membrane 552 x 349 8.8 Knife tip 20 mm. from membrane 453 x 437 9.3 Knife tip 35 mm. from membrane 613 x 453 6.5 Knife tip 35 mm. from membrane