RU2779927C2 - Explosion-proof case with internal pressure relief - Google Patents

Abstract

FIELD: explosion protection.

SUBSTANCE: invention relates to an explosion-proof case, first of all single- or multi-chamber case with explosion protection type Ex-d. The case with explosion protection type Ex-d contains an arrangement of walls having several walls, which enclose an inner cavity. At least two walls are equipped with material with open pores, located inside the case, which does not have fire-barrier properties, and the case is equipped with at least one pressure relief device, which is a gas-permeable fire barrier providing communication of the inner cavity of the case with the environment and/or with an expanding volume.

EFFECT: increase in the efficiency of pressure relief.

12 cl, 4 dwg

Description

The subject of the invention is an explosion-proof enclosure, primarily a single- or multi-chamber enclosure with the type of protection Ex-d (type of protection "explosion-proof enclosures" d "" in the terminology of GOST IEC 60079-1-2013).

In hazardous areas, enclosures with type of protection Ex-d are often used. Such housings are made so strong that they withstand the ignition of an explosive gas mixture occurring in their internal cavity and, as a result of the resulting explosion, the subsequent increase in pressure. In addition, the housings are designed in such a way that flames or incandescent particles, acting as sources of initiation, cannot get out of them. If there are gaps, they should be of a minimum length and not exceed a maximum width. The openings in the housing are provided with pressure relief elements, also called flame filters, which prevent a flame that has broken out in the housing from penetrating and igniting an explosive mixture present in the environment, and, on the other hand, they cause pressure equalization with the environment.

DD 261063 A3 describes an explosion-proof housing with a porous element located in its internal cavity, for example, made of slag wool, glass wool, metal or ceramic, with open through pores or gaps. Such a housing element should result in an explosion pressure reduction of approximately 90%.

DE 19860286 B4 discloses a housing provided for a monitor, the interior of which is partially filled with a porous damping material to reduce the explosion pressure. The material has many small cross-sectional, not closed, but through channels in the form of pores or gaps. As a result, the explosion pressure must be reduced to approximately 10% of the explosion pressure that would otherwise occur in an empty vessel.

Further, DE 102014206433 B3 proposes the arrangement of a tablet computer in an explosion-proof housing provided with a glass plate, wherein a damping element made of mineral wool, quartz wool, glass wool, open-pore metal wool or the like is located in the tablet computer.

The known housings with open-cell elements are partly special solutions that are relatively wide and/or adapted to special conditions, such as tablet computers.

DE 102013109259 A1, on the other hand, describes an explosion-proof enclosure of the type of protection "flameproof enclosure" (Ex-d), in the enclosure wall of which a porous pressure relief element is provided, through which the explosion pressure generated in the enclosure can penetrate to the outside. This principle is also used in housings according to US 4180177 and also according to DE 102010016782 B4.

Such pressure relief elements, when such housings are located in a hostile environment, are subject to contamination or, in the event of exposure to weather conditions, infection, icing and/or corrosion. Accounting for such circumstances leads to higher costs.

The object of the invention is to propose a concept for an explosion-proof enclosure which is universally applicable and low cost.

This problem is solved by means of a housing according to paragraph 1 of the claims.

The housing according to the invention comprises a wall arrangement having several walls that enclose an internal cavity, wherein at least two walls are provided with an open-cell material (open-cell material) located inside the housing (open-cell material) that does not have flame retardant properties, and the housing is provided with at least one reset device pressure, which is a gas-permeable flame arrester, providing communication of the internal cavity of the housing with the environment and / or with the expansion volume.

By arranging the open-cell material on two different, for example opposite or at an angle to each other, walls, the shock wave generated in the housing is damped particularly effectively. This is true both in the case when each of the walls having an open-pore material has this material over the entire area, and in the case when, on one or more walls with an open-pore material, this material covers only a part of the specified wall.

The use of at least two or more wall surfaces for deposition of an open-cell material that dampens a shock wave impinging on or passing along it results in a large damping surface and thus a strong damping effect, even if only relatively thin layers of open-cell material are used. pores. As a result, the part of the internal cavity of the housing available for mounting the components is only slightly reduced due to the open-cell material. In the housing, the walls may be partially or completely lined with a porous material. The porous materials act, on the one hand, as a non-flammable relief volume and, on the one hand, as an extinguishing volume for the penetrating flame front. The spherical front of the shock wave is absorbed immediately in the shortest possible time over a large surface area, and cooling and absorption of unburned gases is achieved. Thus, firstly, the amount of gas involved in combustion or explosion decreases, and secondly, due to cooling of the gas, the pressure decreases. By completely lining the inside of the body with open-cell material, an optimal surface/volume ratio for the body is obtained.

By arranging the open-cell material, preferably exclusively on the walls, a large continuous installation volume is obtained for equipment, switches and the like.

Preferably, the open-cell material is located directly adjacent to at least two walls. Due to this, this heat transfer between the open-cell material and the casing wall cools the open-cell material, so that it has a strong depressurization effect. The housing wall forms a heat accumulator thermally connected to the open-pore material.

The open cell material may be bonded over the entire area, permanently, or only in some places permanently, to the walls of the flameproof enclosure. To this end, the porous material can be welded to the walls or, if the body is made by casting, connected to the walls of the body by being introduced into a mold by primary shaping. Positive and/or non-detachable connection options may be used. For example, the open cell material may be enclosed by a lattice structure connected to the wall arrangement. The lattice structure may be a metal mesh, a perforated metal sheet, a plastic lattice, or the like.

The porous material is preferably formed as a plate or mat of substantially constant thickness such that the surface facing away from the wall is located parallel or at an acute angle to the wall. As a result, in the inner cavity, at least two surfaces of the open-cell material are essentially opposite to each other or at an angle to each other. Both lead to effective damping of the dynamic flame front.

Pressure relief elements can be provided at wall locations free of open-pore material or at wall locations covered with open-pore material. While the open cell material itself does not or should not have flame retardant properties, fire retardation i. blocking the exit of the flame to the outside, provided by one or more pressure relief elements. The open-cell material primarily serves to cool the gas and thus to absorb heat energy and reduce pressure peaks. With respect to the gas flow, the heat absorption device and the flame arrester formed by the open-pore material are located one after the other. By combining a non-flame retardant material with a flame retardant, pressure relief is created with improved efficiency. This is true regardless of whether the open cell material is attached only to the inside of one wall of the housing or to several walls of the housing.

In a preferred embodiment, however, the pressure relief element and thus the external pressure equalization can be omitted, while the open-cell material attached to the inside on the walls leads to rapid cooling and thus to a very significant pressure relief. The open-cell material can be formed by one or more elements of metal wool, sintered metal particles, metal fibers, especially stainless steel fibers, other metal fibers, metal wires, metal strips, mineral fibers such as glass fiber, rock wool, quartz fiber, etc. The open cell material may have a lattice structure, a honeycomb structure or a fabric structure and be formed primarily from a plurality of stacked lattice, honeycomb or fabric structures. They can lie on top of each other loose or, for example, be connected by sintering or by another method. In elements made of wire or fibrous material, we can talk about non-woven layouts, that is, layers of entangled fibers with felted, but not physically fixed fibers. If necessary, the fibers can also be bonded to each other, for example by means of a binder or by means of sintering. The fibers lead to cooling of the absorbed shock wave due to heat absorption and to the damping of the kinetic energy of the shock wave due to internal friction between the fibers. A material with a high heat capacity is preferred, such as rock wool or ceramic wool.

The fibrous material of the open cell material may be pre-compressed into a plate, cuboid, or other shape element, which may be enclosed in a housing, glued or screwed on, or may be held by a frame. However, the compression of the fibrous element is preferably so weak that the distances and gaps of the porous materials lie at least in some places above the limiting gap width of classical explosion protection, i.e. cooling effect, flow effect or other kinetic effects that could prevent ignition. the presence of gas in the material or the passage of the flame front through the material, are absent or absent everywhere. First of all, if the open-cell material has a high heat capacity, such as glass fibres, quartz fibres, ceramic fibres, stone fibres, a high pressure relief is nevertheless achieved.

The open-cell material can also be so fixed with inorganic or organic binders that a deformation-resistant open-cell element is produced. It should not inevitably adjoin the wall. Such a preformed, fixed fibrous element may be located in the housing and be accessible from four, five or six sides. It performs pressure relief also without adjoining the wall and can be used as an alternative or in addition to the open-cell casing linings described above. Also located on the wall of the housing material with open pores can be stabilized in its form by means of an organic or inorganic binder.

Embodiments of the invention follow from the claims, the drawing and the description. Shown on:

fig. 1 shows a housing according to the invention with various pressure relief measures, schematic representation,

fig. 2 is a fragment of the open cell pressure relief element of the housing according to FIG. one,

fig. 3 and 4 show other embodiments of the housing according to the invention, respectively, in cross section.

In FIG. 1 shows an explosion-proof enclosure 10 comprising several walls 11, 12, 13, 14 delimiting an internal cavity isolated from the outside. The walls 11-14 together with the bottom and the lid, not shown further, form a wall arrangement 16. The bottom and cover of such a housing can be connected to the walls 11-14 permanently or detachably. Further, they are also considered as walls.

Structural elements and components, such as printed circuit boards 17, 18 with electrical structural elements located on them, can be located in the internal cavity 15, which can serve as sources of initiation.

On at least two walls 11, 12 of the body 10, there is an open-pore material 19, 20, for example, in the form of plates, elements or mats, covering the corresponding wall 11, 12, respectively, completely or partially. The open cell material may contain fibers or particles in a movable form or in an interconnected form. It may contain ordered or randomly made and arranged pores. For example, we can talk about lattice structures with one or more lattices of metal wires, stranded wires or strips located one above the other, arranged in the form of a lattice or like a fabric. Metal wires, metal stranded wires or metal strips are interconnected or lie on top of each other, for example in loose layers. The metal wires, ribbons or wires may also be formed into another woven article, such as a woven fabric or plate stack. The wires, stranded wires or strips may also be composed of other heat-absorbing material.

The open-pore material is here preferably located adjacent directly to the respective wall 11, 12 and further preferably connected to it. The connection can take place by gluing all over, by welding, or by other connection measures leading to a permanent partial or complete connection. Alternatively or additionally, the open cell material 19, 20 may be held in a receptacle formed by, for example, a lattice structure 21. The lattice structure 21 may be a perforated metal casing, a metal mesh, a box, or the like, connected ) with the housing 10 and separating(th) material 19, 20 with open pores from the rest of the internal cavity 15.

The open-cell material 19, 20 has, on its side facing the inner cavity 15, surfaces 22, 23 arranged, as shown, at an angle to each other which is less than 180°.

As an alternative to, or in addition to, the open-cell material 20, another portion 24 of the open-cell material is located opposite the open-cell material 19. It may be the same or different open cell material as compared to materials 19, 20. It may have the same or different thickness. In the same way, open-cell materials 19, 20 may have the same or different thickness. The material 24 has a surface 25 facing the inner cavity 15, which lies opposite the surface 22 and is located at an angle of, for example, 90° to the surface 23.

The open cell material 19, 20 and/or 24 forms an internal pressure relief device. Another internal pressure relief device can be formed by an open cell element 26, which is located freely on at least four, preferably five or six sides, that is, not adjacent to any of the walls of the wall arrangement, in the internal cavity 15 of the housing 10 The following explanations for element 26 also apply optionally to open-cell material 19, 20.

Preferably, the open cell element 26 is a fibrous element, the fibers of which are interconnected by means of a binder. In FIG. 2 shows a schematic fragment of the element 26. As can be seen, several fibers 27 in a spatially disordered arrangement are intertwined with each other and, at least in some places of intersection, are connected by means of a binder 28. In the case of fibers, we can talk about metal fibers or mineral fibers, in particular glass fibers, quartz fibers, stone fibers, ceramic fibers. The binder 28 may be an artificial resin, especially a phenolic resin. The proportion of resin is so small that the pores present between the fibers 27 remain open. However, it is so large that the open cell element 26 has a significant resistance to deformation, so that when an explosion is initiated in the internal cavity 15, it does not disintegrate and, if possible, does not release or releases only a safe amount of fibers.

Alternatively, the fibers, wires, filaments, or particles that make up element 26 may be arranged in an orderly manner and still be bonded together by a binder. The fibers 27 can be identical fibers, which can also be used for the open-cell material 19, 20, 24. It can also be pre-compressed and optionally provided with a binder.

Optionally, the housing 10 may be provided with at least one pressure relief device 29 and/or 30 providing an aerodynamic connection between the interior of the housing and the environment. Both pressure relief devices 29, 30 are porous gas-permeable elements with a gap width and a gap length that provide fire protection, i.e. preventing flashover. The pressure relief device 29 is located on a porous material-free section of the wall 14 of the body 10. Additionally or alternatively, the pressure relief device 30 provided, as viewed from the interior cavity 15, is covered with an open-cell material 25 . However, it does not interfere with the flow of gas. Such a combination of an endothermic, but not flame retardant, open cell material 25 and a pressure relief device 30 can be used independently of the open cell material 19, 20.

In FIG. 3 shows a modified form of the housing 10 according to the invention. The previous description is valid when using the items already entered respectively. Unlike the housing 10 described above, the housing 10 according to FIG. 3 has a porous material 19, 20, 25, 31 on all four walls 11, 12, 13, 14 of the body and optionally additionally on a not shown bottom and/or lid. The open-pore material 19, 20, 25, 31 forms a locally discontinuous or continuous layer running along the walls, trapping the flame front flared up in the inner cavity 15 and absorbing the resulting shock wave.

In the case shown in FIG. 4 of the body 10 is a case based on the body 10 according to FIG. 3 form of execution. Optionally, this housing has a pressure relief device 32, made as a fire barrier and located on the wall 14, to which the expansion volume 33 adjoins. It can be separated by means of an incomplete housing 34 from the environment and isolated from it, or have holes through which it communicates with environment.

Additionally or alternatively, a pressure relief element 35 may be provided in wall 12 to release pressure to the environment. The pressure relief flame arrester 35 can, in turn, be covered from the inside with a porous material 20 or lie loose. In addition, a device 36 with a through hole can be provided, through which, for example, the shaft 37 is passed through the wall 12 of the housing. To do this, the shaft 37 with the housing wall 12 can define a flame-tight gap 38. The shaft 37 can be passed through the open-cell material 20 and transmit movements between the elements outside the housing 10 and the elements inside the housing 10.

The housing 10 according to the invention can be provided on the inside with an open-cell lining that preferably surrounds at least two sides of the housing 10 in order to reduce the internal explosion pressure. Additionally or alternatively, a molded element made of an open-cell material, in particular a fixed fibrous material, may be located in the body.

Reference designations

10 building

11-14 walls

15 internal cavity

16 wall layout

17, 18 printed circuit boards

19, 20 open cell material

21 lattice structures

22, 23 open cell surface

24 section open cell material

25 surface

26 open cell element

27 fibers

28 binder

29, 30 pressure relief device

31 open cell materials

32 pressure release element

33 expansion volume

34 incomplete body

35 pressure relief element

Claims (12)

1. Housing (10) with the type of protection Ex-d, containing the layout (16) of the walls, having several walls (11, 12, 13, 14), which cover the internal cavity (15), with at least two walls (11, 12) are provided with an open-cell material (19, 20) located inside the housing that does not have flame retardant properties, and the housing (10) is equipped with at least one pressure relief device (29, 30, 32, 35, 38), which is a gas-permeable flame arrester, providing communication of the internal cavity (15) of the housing with the environment and/or with the expansion volume (33). 2. A housing according to claim 1, characterized in that the open-cell material (19, 20) is positioned adjacent directly to the walls (11, 12) of the housing. 3. Housing according to one of the preceding claims, characterized in that the material (19, 20) on each of the walls (11, 12) to which it is attached has a surface (22, 23) facing away from the wall, facing the inner cavity ( fifteen). 4. Housing according to claim 3, characterized in that the surface (22, 23) facing away from the wall is arranged parallel to or at an acute angle to the wall (11, 12). 5. Housing according to one of the preceding claims, characterized in that the open-pore material (19, 20) is a fibrous material. 6. Housing according to one of the preceding claims, characterized in that the open-cell material (19, 20) is enclosed by a lattice structure (21) connected to the wall arrangement (16). 7. Housing according to one of the preceding claims, characterized in that the open-pore material (19, 20) carrier area of the wall (11, 12) is solid or has only fire barrier gaps. 8. Housing according to one of the preceding claims, characterized in that the material-carrying (19, 20) area of the wall (11, 12) with open pores has at least one opening provided with a gas-permeable fire barrier (30). 9. The body according to claim 1, characterized in that in the internal cavity (15) there is an element (26) with open pores, consisting of a fixed to retain its shape by means of a binder (28) the layout of metal or mineral elementary fibers (27). 10. Housing according to claim 9, characterized in that the arrangement of elementary fibers (27) contains metal wires, metal stranded wires, metal tapes, metal fibers, glass fibers, quartz fibers, mineral-based fibers, ceramic fibers or a mixture of them. 11. Housing according to claim 9, characterized in that the binder is an artificial resin. 12. The housing according to claim. 9, characterized in that the binder is an inorganic binder material.

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