HOUSING WITH INTERNAL PRESSURE REDUCTION

Description

[0001] The invention relates to an explosion-proof housing, in particular a single- or multi-chamber housing of protection type Ex-d.

[0002] In potentially explosive atmospheres, enclosures of protection type Ex-d are frequently used. These enclosures are designed to be so robust that they can withstand the ignition of an explosive gas mixture inside and the subsequent pressure increase resulting from the explosion. Furthermore, the enclosures are designed to prevent flames or incandescent particles that could act as ignition sources from escaping. If gaps are present, they must have a minimum length and must not exceed a maximum width. Any openings in the enclosure are fitted with pressure relief devices, also known as flame arresters, which prevent a flame ignited inside the enclosure from escaping and igniting any explosive mixture in the surrounding area, while simultaneously equalizing the pressure with the environment.

[0003] DD 261063 A3 describes an explosion-proof enclosure with a porous body located inside it, for example made of slag wool, glass wool, metal, or ceramic with open, continuous pores or gaps. Such a body located inside the enclosure is intended to reduce the explosion pressure by approximately 90%.

[0004] German patent DE 198 60 286 B4 discloses a housing intended for a screen, the interior of which is partially filled with a porous damping material to reduce the explosion pressure. The material has a multitude of small, open, but continuous channels in the form of pores or gaps. This is intended to reduce the explosion pressure to only about 10 percent of the explosion pressure that would otherwise occur in the empty housing.

[0005] Furthermore, DE 10 2014 206433 B3 proposes the arrangement of a tablet computer in an explosion-proof housing equipped with a glass pane, wherein a damping element made of open-pore rock wool, quartz wool, glass wool, metal foam or the like is arranged in the tablet computer.

[0006] From DE 198 26 911 A1, a housing of the type "pressure-resistant encapsulation" is known, in which gaps are present due to its design. To protect against flame penetration, such gaps are fitted with seals containing a packing of spheres.

[0007] From DE 10 2009 025 296 A1, an explosion-proof enclosure is known whose interior is lined across its entire surface with shock-absorbing material. The material can, for example, be a metallic honeycomb structure. Alternatively, if a porous organic filler and organic fibers are used for reinforcement, the material can be bonded with epoxy resin and sprayed onto the inside of the enclosure.

[0008] The well-known enclosures with bodies made of open-pore material are partly special solutions that are relatively space-consuming and / or are very adapted to the specific requirements, such as tablet computers.

[0009] In contrast, DE 10 2013 109 259 A1 describes an explosion-proof enclosure of protection type flameproof encapsulation (Ex-d), in whose enclosure wall a porous pressure relief element is provided through which an explosion pressure built up inside the enclosure can escape to the outside. This principle is also used in the enclosures according to US 4,180,177 and DE 10 2010 016 782 B4.

[0010] Pressure relief devices of this type are subject to contamination when such housings are installed in harsh environments, or to microbial growth, icing, and / or corrosion when exposed to the elements. Taking such factors into account increases the complexity of the design.

[0011] The object of the invention is to provide a concept for an explosion-proof enclosure that is versatile and inexpensive.

[0012] This problem is solved by the housing arrangement according to claim 1: The housing according to the invention comprises a wall arrangement with several walls that enclose an interior space. At least two of the walls are provided with an open-pore material.

[0013] The open-pore material allows for cooling and thus a significant reduction in gas pressure following an explosion.

[0014] The area of ​​the wall supporting the open-pore material may have an opening which is fitted with a gas-permeable, flame-resistant body. The terms flame-resistant and ignition-resistant are used synonymously in this application. A flame-resistant or ignition-resistant body is also referred to as a pressure relief body.

[0015] In certain embodiments, the open-pore material is positioned in front of the flameproof body, i.e., between the interior of the housing and the flameproof body. The open-pore material cools the gas in the event of an explosion, ensuring that the gas reaches the flameproof body in a cooled state.

[0016] In preferred embodiments, the flameproof body is designed, alone or at least primarily, and particularly preferably tested (type and / or unit testing), to ensure flameproofness, for example, to meet the flameproofness test (e.g., for groups IIA, IIB, or IIC according to standard IEC / EN 60079-1). The body is thus designed, due to its gap dimensions, to ensure, even without the upstream open-pore material, that hot gas or plasma, especially sparks, cool down or extinguish upon passing through the flameproof gaps of the body to such an extent that an explosive atmosphere outside the interior is not ignited by the gas or plasma passing through the gaps. However, in these embodiments, the flameproof body alone may not be sufficient to achieve the target temperature class of the surface of the flameproof body or the housing.Preferably, the combination of open-pore material and flameproof body is designed to ensure that, in the event of an explosion inside the enclosure, the surface temperature of the flameproof body and / or the housing remains below a specified maximum temperature. In these embodiments, only the arrangement with the open-pore material in front of the flameproof body is designed and preferably tested (type-tested or individually tested) to achieve the desired temperature class (e.g., classes T1, T2, T3, T4, T5, or T6 of IEC / EN 60079-0) for the surface temperature of the flameproof body or the housing. Preferably, the open-pore material alone, i.e., without the combination with the flameproof body, is not flameproof. Therefore, the stringent requirements regarding the gap size to prevent flame penetration are applied only to the body, not to the open-pore material.In particular, the average ratio of gap width to gap length in the flame-resistant body can be smaller than in the open-pore material.

[0017] It is also possible that the flameproof body alone is designed and preferably tested, in particular type-tested or individually tested, for both ignition-arresting resistance and for maintaining a temperature of the housing or body below a specified maximum temperature. In such embodiments, the arrangement of the open-pore material and the flameproof body can be designed and preferably tested, in particular type-tested or individually tested, to meet a higher, in particular the next higher, temperature class. The higher the temperature class (e.g., T1 to T6 of standard IEC / EN 60079-0), the lower the maximum permissible surface temperature. Even in these embodiments, the open-pore material alone is preferably not ignition-arresting.

[0018] Alternatively or additionally, it is possible that the flameproof body alone is designed and tested, in particular type-tested or individually tested, for ignition penetration resistance of a specific group (e.g., IIA or IIB of standard EN / IEC 60079-1), and that the arrangement with open-pore material and the flameproof body is designed and preferably tested, in particular type-tested or individually tested, for a higher group with regard to ignition penetration resistance. While the flameproof body alone, for example, achieves group IIA, the combination of open-pore material and flameproof body is designed and tested, in particular type-tested or individually tested, for example, to achieve group IIB. Alternatively, for example, the combination can be designed to achieve group IIC based on group IIA or IIB for the flameproof body.The open-pore material alone is preferably not designed to be flameproof.

[0019] In preferred embodiments, the open-pore material enhances the flame-resistant properties of the body, such that it meets the requirements of a more stringent maximum surface temperature requirement (lower maximum temperature) and / or a higher ignition penetration resistance class. According to the inventive concept for the simple and modular construction of an open-pore material, the open-pore material is formed with loose particulate material within a container structure. The container structure has at least one gas-permeable boundary structure, which is distinct from a wall of the housing that encloses the interior. The boundary structure separates a space for the particulate material from the interior of the housing. The boundary structure can, for example, be formed by a grid arrangement. The boundary structure can also be formed by a woven fabric or a non-woven fabric.In some embodiments, the flame-resistant body can form part of the container structure by acting as a barrier to the loose particulate material. In other embodiments, the container's boundary structures are separate from the flame-resistant body.

[0020] The loose particulate material can, for example, comprise spheres, particularly hollow spheres or spheres that do not enclose a cavity, granules, or other bulk material. The particles are preferably not bonded to one another, in particular not sintered, but rather movable relative to each other outside the container structure. The particulate material is preferably free-flowing. In some embodiments, the particles cannot interlock and / or are not intertwined. In other embodiments, some particles may interlock, but remain unconnected overall. For example, the loose particulate material can be metal shavings and / or plastic shavings. In some embodiments, the loose particulate material is free of fibers, fiber segments, strips, or strip segments.

[0021] Preferably, no static pressure is exerted on the loose particulate material by means of the container structure. Preferably, the loose particulate material in the container structure is free from static pressure apart from hydrostatic pressure and atmospheric pressure.

[0022] The loose particulate material can have a selected average particle size and / or a selected particle size distribution. In particular, the container structure can have a targeted mixture of differently sized particles.

[0023] The container structure can hold a maximum quantity, particularly with regard to the mean particle size and / or the size distribution of the bulk material, i.e., the loose particulate material. According to the invention, the container structure contains less than the maximum quantity of the loose particulate material; the fill level can therefore be less than 1.

[0024] The container structure can have at least two compartments. The particles in one compartment can be the same as, or different from, the particles in another compartment in composition, shape, and / or size. If the bulk materials or fillings with which the compartments are filled differ, for example, with regard to particle size, particle shape, material, total surface area of ​​the particles, and / or total heat capacity of the particles, and / or bulk density or fill level, the cooling and / or pressure relief effect of the porous material can be optimized by arranging the compartments in series compared to an embodiment with the same filling in the compartments or with only one compartment. The first compartment can, for example, be directly exposed to the "flame front," i.e., arranged between the ignition source and one or more further compartments. This first compartment can, for example, be designed with respect to...The bulk material density in the first compartment is optimized for kinetic energy conversion, while the downstream bulk material is optimized for cooling. The downstream bulk material may, for example, have a larger surface area and / or greater heat capacity compared to the bulk material in the first compartment, and the density of the loose particulate material in the first compartment may be higher than the density of the loose particulate material in the downstream compartment. The specific properties of these bulk material layers can improve the overall pressure relief system.

[0025] The loose particulate material in the container structure does not need to provide ignition penetration protection. Its primary function is to dampen pressure surges resulting from an explosion and / or to cool hot explosion gases. If the particles are mobile relative to each other, kinetic energy from an explosion pressure front can be transferred to the particles, and this energy can be passed from particle to particle through collisions and / or friction.

[0026] According to the invention, at least two of the walls of the wall assembly are provided with an open-pore material. If an open-pore material is arranged on at least two of the walls of the wall assembly, a pressure wave generated in the housing can be particularly efficiently dissipated by arranging the open-pore material on two different walls, for example, walls that are opposite each other or at an angle to each other. This applies both when each of the walls provided with the open-pore material is fully covered with this material, and when, in the case of one or more of the walls, the material only extends over a partial area of ​​the affected wall.

[0027] Utilizing at least two or more wall surfaces for the application of open-pore material that dampens an impacting or propagating pressure wave results in a large active damping area and thus a high damping effect, even when only relatively thin layers of open-pore material are used. The thickness of the layer can be, for example, less than one-tenth or one-twentieth of the housing's inner diameter between opposing walls. This means that the open-pore material only minimally reduces the interior space available for components. The housing walls can be partially or completely lined with open-pore material. The open-pore materials act both as a non-ignitable pressure relief volume and as an extinguishing volume for an incoming flame front.A spherical explosion front is immediately and rapidly absorbed over a large area by the lining, resulting in cooling and absorption of unburned gases. This reduces the amount of gas participating in the combustion or explosion and, through gas cooling, lowers the pressure. Completely lining the inside of the housing with the open-pore material ensures an optimal surface area to volume ratio.

[0028] By arranging the open-pored material, preferably exclusively on the walls, a large, continuous installation space is obtained for equipment, switches, and the like.

[0029] Preferably, the open-pore material is arranged in direct contact with at least two walls. The resulting heat transfer between the open-pore material and the housing wall cools the open-pore material, giving it a high pressure-reducing effect. The housing wall forms a thermally connected heat storage medium to the open-pore material.

[0030] In embodiments not according to the invention, the open-pore material can be fully bonded to the walls of the pressure-resistant housing, either by a material bond or only in specific locations. This can be achieved by welding the porous material to the walls or, if the housing is manufactured by casting, by inserting it into the mold and forming it into the housing walls. Other mechanical, form-fitting, and / or material-bonded connection methods can be used. For example, the open-pore material can be enclosed by a grid structure that is connected to the wall assembly. The grid structure can be a wire mesh, a perforated sheet, a plastic mesh, or the like.

[0031] The open-pore material can have a surface facing away from the wall on each of the walls to which it is attached, and which faces the interior. This surface can be arranged parallel to the wall or at an acute angle to it. In embodiments not according to the invention, the porous material can be designed as a plate, mat, or filling of essentially constant thickness, so that the surface facing away from the wall is arranged parallel to or at an acute angle to the wall. This results in at least two surfaces of the open-pore material being essentially opposite each other or at an angle to each other in the interior. Both configurations lead to effective damping of a dynamically propagating flame front.

[0032] Pressure relief elements can be arranged on areas of the wall free of open-pore material or on areas of the wall covered by open-pore material. While the open-pore material itself does not provide, nor is it required to provide, protection against flame penetration, flame penetration protection to the outside is provided by the pressure relief element(s). The open-pore material primarily serves to cool the gas and thus absorb heat energy and reduce pressure peaks. With respect to the gas flow, the heat absorption device formed by the open-pore material and the flame arrestor are arranged in series. The combination of the non-flame-resistant material with a flame arrestor creates pressure relief with improved effectiveness. This applies regardless of whether the open-pore material is applied only to the inside of a single housing wall or to multiple housing walls.

[0033] In a preferred embodiment, however, pressure relief elements and thus external pressure equalization can be dispensed with, as the open-pore material attached to the inside of the walls leads to rapid cooling and thus to a very significant pressure reduction. In various non-claimed embodiments, the open-pore material can be formed by one or more bodies made of metal foam, sintered metal particles, metal fibers, in particular stainless steel wool, other metal fibers, metal wires, metal strips, mineral fibers such as glass fibers, rock wool fibers, quartz fibers, and the like. The open-pore material can have a grid structure, a mesh structure, or a woven structure and, in particular, be formed from several superimposed layers of the grid, mesh, or woven structure. These can lie loosely on top of one another or, in embodiments that do not correspond to the claimed invention, e.g.,The components can be bonded together by sintering or another technique. The wire or fiber components can be needle-felted arrangements, i.e., a tangled fiber fabric with interlocked but not physically bonded fibers. If required, the fibers can also be physically bonded to one another, for example, by a binder or by sintering. The fibers cool the absorbed pressure wave by absorbing heat and dissipate the kinetic energy of the pressure wave through internal friction between the fibers. A material with high heat storage capacity, such as rock wool or ceramic wool, is preferred.

[0034] In embodiments not corresponding to the claimed invention, the fibrous material of the open-pore material can be pre-pressed into a body in the form of plates, cuboids, or other shapes, which can be inserted, glued, or screwed into the housing, or which are held by a frame. However, the density of the fibrous body is preferably so low that the gaps and spaces of the porous material are, at least in some places, above the limiting gap width of conventional explosion protection; that is, cooling effects, flow effects, or other kinetic effects that could prevent ignition of gas present in the material or passage of the flame front through the material are either absent or not completely present.Particularly when the open-pored material has a high heat capacity, as is the case with glass fibers, quartz fibers, ceramic fibers, and rock fibers, a high pressure reduction is still achieved.

[0035] In embodiments that do not correspond to the claimed invention, the open-pored material can also be bound by inorganic or organic binders to such an extent that an open-pored, dimensionally stable body is formed. This does not necessarily have to be connected to the wall. According to the invention, an open-pored, dimensionally stable body is formed from a container structure which is partially filled with loose particulate material.

[0036] Such a body containing bulk material can also be arranged within the housing, accessible from four, five, or six sides. It reduces pressure even without a wall connection and can be used as an alternative or additional to the housing linings with open-pore material described above. The loose, particulate material in the container structure, either on the wall or in the interior, is characterized precisely by the fact that the particles are not chemically bonded to one another, thus creating an open-pore body with a large surface area. The container structure can be, for example, a cuboid, a cube, or any other three-dimensional body in which the bulk material is housed.

[0037] An arrangement consisting of a porous material and a flame-resistant body can be provided by means of an unclaimed method. The flame-resistant body is designed and preferably tested for a specific gas group with respect to preventing ignition breakdown, independently of the porous material. For example, according to one of groups IIA, IIB, or IIC as defined in EN / IEC 60079-1. However, to ensure compliance with an upper temperature limit for the flame-resistant body and / or any housing to which the body is fitted, the arrangement of the porous material and the body is designed.

[0038] In a further unclaimed method for providing a device with increased flameproof safety, open-pore material is arranged on a body which body is designed for flameproof safety of a certain group and is preferably type-tested or individually tested, wherein the arrangement resulting from the flameproof material and the open-pore material is designed for a higher level of flameproof safety than the flameproof body.

[0039] Further features and embodiments of the invention will become apparent from the claims, the drawing, and the following description. The drawing shows: Figure 1 a housing according to the invention with various measures for pressure reduction, in schematic representation; Figure 2 a section of a pressure-reducing open-pore body of the housing according to Figure 1 ; Figure 3a and 4Further embodiments of the housing according to the invention are shown in schematic cross-sectional representations. Figure 3b a section of an open-pore material of the housing according to Figure 3a . Figure 5a another embodiment of a housing according to the invention, Figure 5b a section of the housing according to Figure 5a , Figure 6 a section of a housing in a further embodiment, Figure 7 a section of a housing in a too Figure 7 modified embodiment Figure 8 a section of a housing in a further embodiment, Figure 9 a section of a housing of a further embodiment, Figure 10 a section of a pressure-reducing open-pore body of the housing according to Figure 9 and Figure 11 a diagram to illustrate procedures.

[0040] In Figure 1Figure 10 illustrates an explosion-proof enclosure 10 comprising several walls 11, 12, 13, 14 that enclose an internally sealed space 15. The walls 11 to 14, together with a base and a lid (not shown), form a wall assembly 16. The base and lid of this enclosure can be permanently or detachably connected to the walls 11 to 14. They are also considered walls.

[0041] The interior space 15 may contain components such as printed circuit boards, 17, 18 with electrical components arranged on them, which may form ignition sources.

[0042] Open-pore material 19, 20, for example in the form of plates, solids, or mats, is arranged on at least two walls 11, 12 of the housing 10, covering each wall 11, 12 completely or partially. The open-pore material comprises movable particles. It can contain regularly or irregularly formed and arranged pores. In non-claimed embodiments, it can be a grid structure with one or more superimposed grids of metal wires, ropes, or strips arranged in a grid-like or woven pattern. The metal wires, ropes, or strips are connected to one another or lie loosely on top of each other, e.g., in layers. The metal wires, strips, or wires can also be formed into a different mesh fabric, such as a knitted or woven fabric. The wires, ropes, or strips can also consist of another heat-absorbing material.

[0043] In unclaimed embodiments, the open-pore material is preferably arranged directly adjacent to the respective wall 11, 12 and further preferably connected to it. The connection can be made by full-surface bonding, welding, or other joining methods that result in a material-bonded partial or full-surface connection. According to the invention, the open-pore material 19, 20 is held in a receptacle, which is formed, for example, by a grid structure 21. The grid structure 21 can be a perforated sheet metal housing, a wire mesh, a cage, or the like, which is connected to the housing 10 and keeps the open-pore material 19, 20 away from the rest of the interior 15. To form an open-pore material, the grid structure 21 is filled with loose particulate material, the fill level being less than 1.A high degree of filling may be necessary, for example, in embodiments where the open-pore material is arranged in front of a pressure relief element to ensure that gas from an explosion front must always pass through the open-pore material before reaching the pressure relief element. A lower degree of filling may suffice for an open-pore material arranged in a closed area of ​​a wall or accessible from one, two, ..., or six sides within the interior. The loose particulate material can comprise regular, for example, spherical, or irregular bodies, for example, grains of sand. The loose particulate material is preferably non-flammable. Suitable pourable bodies include, for example, glass spheres, hollow glass spheres, metal spheres, ceramic spheres, polymer granules, intumescent granules, foam spheres / bodies, fiber spheres / bodies, or other loose fills.In some embodiments, the container structure formed by the grid structure 21 can be filled with chips as loose particulate material. The grid structure follows the walls 11 and 12 and is thus arranged at an angle. In general, the grid structure can be adapted to the housing shape and / or wall shape of the housing, e.g., maintaining a constant distance from the walls 11 and 12 along the wall.

[0044] The open-pore material 19, 20 has surfaces 22, 23 on its side facing the interior 15, which are arranged at an angle to each other as shown, which is less than 180°.

[0045] Alternatively or in addition to the open-pore material 20, a further section 24 of open-pore material is arranged opposite the open-pore material 19. This can be the same or a different open-pore material as materials 19 and 20. It can have the same or a different thickness. Likewise, the open-pore materials 19 and 20 can have the same or different thicknesses. Material 24 has a surface 25 facing the interior 15, which is opposite surface 22 and is arranged at an angle of, for example, 90° to surface 23.

[0046] The open-pore material 19, 20 and / or 24 forms an internal pressure relief device. An additional or alternative internal pressure relief device can be formed by an open-pore body 26, which is arranged in the interior 15 of the housing 10 free on at least four, preferably five or six sides, i.e., not abutting any of the walls of the wall arrangement. The following descriptions of the body 26 also optionally apply to the open-pore material 19, 20.

[0047] In a non-inventive embodiment, the open-pored body 26 is a fibrous body whose fibers are connected to each other by a binder. Figure 2Figure 26 schematically illustrates a section of the body 26. As can be seen, several fibers 27 are intertwined in a spatially disordered arrangement and bound at at least some of their intersections by a binding agent 28. The fibers can be metal fibers or mineral fibers, in particular glass fibers, quartz fibers, rock fibers, or ceramic fibers. The binding agent 28 can be a synthetic resin, in particular a phenolic resin. The resin content is so low that the pores between the fibers 27 remain open. However, it is high enough that the open-pored body 26 has considerable dimensional stability, so that it is not dissolved when an explosion is ignited in the interior 15 and releases as few fibers as possible, or at most a harmless quantity.

[0048] Alternatively, the fibers, wires, threads, or particles comprising the body 26 can also be arranged regularly and yet bonded together with a binder. The fibers 27 can be the same fibers used for the open-pore material 19, 20, 24. This material can also be pre-compacted and, if desired, also bonded with a binder.

[0049] According to the invention, the body 26 is formed by a container structure which is partially filled with loose particulate material. The gas-permeable boundary structure of the container structure separates a compartment of the interior for the loose particulate material filling. This allows, for example, a bed of spheres to be placed at any desired location within the housing. The loose particulate material can be, for example, quartz sand or glass particles. The body is preferably free of electrical equipment, in particular free of electrical components. The body itself has gaps which do not need to be flameproof. The gaps formed by openings in the container structure and spaces between particles of the loose particulate material filling do not need to have a standard dimension, so that flameproofness through the gaps is ensured.The body serves solely to relieve pressure in the event of an explosion inside the enclosure. The enclosure does not need to comply with the "sand encapsulation" type of protection (Ex-q, according to standard IEC 60079-5). Due to the degree of filling, the loose particles within the body 26 can still move relative to one another, or the container structure 41 is so full of loose particles that they cannot move relative to one another.

[0050] Optionally, the housing 10 can be provided with at least one pressure relief device 29 and / or 30, which allows a flow connection between the interior of the housing and the environment. Both pressure relief devices 29, 30 are porous, gas-permeable bodies with a gap width and length that prevents flame propagation (ignition propagation). The pressure relief device 29 is arranged in a section of the wall 14 of the housing 10 that is free of open-pore material. The additionally or alternatively provided pressure relief device 30 is covered by the open-pore material 25 when viewed from the interior 15. However, this does not impede gas passage. This combination of heat-absorbing, open-pore, but not flame-resistant material 25 and the pressure relief device 30 can be used independently of the open-pore material 19, 20.

[0051] Figure 3aFigure 1 illustrates a modified embodiment of the housing 10 according to the invention. The preceding description applies accordingly using the reference numerals already introduced. In contrast to the housing 10 described above, the housing 10 shown in Figure 10 features... Figure 3 Porous material 19, 20, 25, 31 is applied to all four walls 11, 12, 13, 14 of the housing and optionally also to the base (not illustrated) and / or the lid. The open-pored material 19, 20, 25, 31 forms a locally interrupted or continuous layer along the walls, which captures a flame front ignited in the interior 15 and absorbs the resulting pressure wave.

[0052] Figure 3aFigure 3 illustrates an embodiment of the open-pore material 31 as a container structure, formed by walls 11, 12, 13, 14 and a temperature-stable additional boundary structure 21, and containing a loose particulate material 39. The interconnected spaces between the particles form open pores 40, thus enabling gas to pass into and / or through the material 31. The particles 39 in the open-pore material 31 of any embodiment can have a uniform size or, as shown, different diameters. The particles 39 can exhibit a selected size distribution that differs from a uniform size distribution.

[0053] The additional boundary structure 21 can, for example, be a grid structure in the form of a wire mesh, perforated sheet, plastic mesh, or the like. An additional boundary structure 21 in the form of a fabric can also be used. Regardless of the specific embodiment, the container structure of the porous material, consisting of walls 11-14 and the boundary structure 21, preferably ensures the flow of gas through the pores of the open-pored material 31. At the same time, the opening widths of the container structure are so small that the bulk material contained therein, i.e., the loose particulate material, remains within the container structure. Preferably, the bulk material is abrasion-resistant so that, during intended use—except in the case of an explosion inside—no dust or smaller particles (friction particles) can be generated by friction between the particles 39.Alternatively or additionally, the container structure is dustproof or friction particle-proof.

[0054] The particles are preferably incompressible at the dynamic pressures that occur during an explosion for which the housing or arrangement is designed. Compared to a compressible open-pore material, for example, a tangled fiber body, this can have the advantage that the spaces between the particles remain open when a pressure front impacts the open-pore material, whereas with an elastically compliant open-pore material, there is a risk that the pores will close precisely when the pressure front impacts the material, thus impairing gas exchange through the material.

[0055] The particles, which are not interconnected, also have a particularly large surface area, making cooling by means of an open-pore material in a container structure containing loose particulate material especially effective. Freely moving particles in a container structure filled to a degree of less than 1 also offer the possibility of converting heat and / or pressure into the kinetic energy of the particles, thus enabling particularly effective cooling and / or pressure reduction. In a less demanding alternative, the container structure 41 can be an open-pore body (e.g., body 26 in Figure 1 ) or open-pored material in such a way that the particles cannot move against each other.

[0056] At the in Figure 4 The illustrated housing 10 is based on the housing 10 according to Figure 3aConstructive embodiment. Optionally, this housing 10 has a pressure relief device 32, which is flame-resistant and arranged in the wall 14, to which an expansion volume 33 is connected. This can be separated from the environment by a partial housing 34 and sealed off from it, or it can have openings through which it communicates with the environment. The embodiment according to Figure 4 As an open-pored material, it has a container structure containing loose particulate material, such as in connection with Figure 3 described.

[0057] Additionally or alternatively, a pressure relief element 35 can be provided in the wall 12, enabling pressure relief to the environment. The flame-resistant pressure relief element 35 can be covered internally by the porous material 20 or be exposed. In particular, the pressure relief element 35 can be covered by loose particulate material within a container structure. The pressure relief element itself can be part of the container structure. Alternatively, a gas-permeable additional boundary structure 42, for example a grid, can be arranged between the pressure relief element and the loose particulate material. The additional boundary structure can be connected to the pressure relief element 35 or not. Furthermore, a feedthrough device 36 can be provided, for example by guiding a shaft 37 through the housing wall 12.For this purpose, the shaft 37 can define a flameproof gap 38 with the housing wall 12. The shaft 37 can be guided through the open-pored material 20 and transmit movements between elements outside the housing 10 to elements inside the housing 10.

[0058] Figure 5a Figure 1 shows an embodiment of a housing 10 not according to the invention, containing an electrical device 17. As shown, only one wall 14 of the housing is provided with a gas-permeable porous material 31, in which the material is arranged wholly (as shown) or partially (projecting into the interior 15 of the housing 10) in an opening in the wall 14 of the housing (see also the enlarged view of the housing shown in Figure 1). Figure 5a drawn section in Figure 5bOther walls 12-14 of the enclosure 10 cannot support porous material or can support porous material in and / or on the walls. A gas-permeable, flame-resistant body 32 is also arranged in the opening. The porous material is arranged between the flame-resistant pressure relief body 32 and the interior 15 of the enclosure, such that the open-pored, gas-permeable material 31 completely covers the pressure relief body 32 against the interior 15, while allowing gas to pass through. In order to pass through the pressure relief body from the interior 15 of the enclosure 10 into the environment of the enclosure 10, the gas must first flow through the open-pored material 31.

[0059] The pressure relief body 32 can be designed in an embodiment without the open-pore material 31 to ensure flameproofness. In particular, the pressure relief body 32 can meet the requirements of a relevant standard, for example, EN 60079-1, regarding the dimensions of the gap of the pressure relief body 32 for a specific class, for example, IIA, IIB, or IIC of EN 60079-1, in order to prevent flameproofness. The type (type test) of the pressure relief body 32 can be designed without the open-pore material 31 arranged upstream of it. Figure 5a of the type shown, or the specific pressure relief body 32 can be used without the one arranged upstream in Figure 5aThe pressure relief body 32, specifically depicted, has been tested (individual test). However, the pressure relief body 32 cannot be specifically designed or suitable to guarantee, without the open-pored material 31 arranged in front of it, a temperature of the outer surface of the pressure relief body 32 or of the housing 10 that does not lead to the thermal ignition of a specific gas on the outside of the housing 10. In particular, the pressure relief body 32 cannot be designed or suitable to meet a specific temperature class of the standard EN / IEC 60079-0.Rather, the combined arrangement of porous material 31 and pressure relief body 32 – in which the porous material and the pressure relief body can be connected or unconnected, in contact or spaced apart – is preferably designed to ensure that the surface temperature of the porous body 32 or the outer surface of the housing 10 does not exceed a predetermined maximum temperature. The arrangement of porous material 31 and pressure relief body 32 is therefore preferably designed to meet a specific temperature class, for example, that of standard EN / IEC 60079-0. In particular, when porous material 31 is connected to the pressure relief body 32, e.g., sintered, it can be considered as two connected segments of an element.However, the design for ignition breakdown safety in embodiments is limited to the pressure relief body 32, while only the combined arrangement of open-pore body 31 and pressure relief body 32 is designed to comply with the requirement of a temperature class.

[0060] According to an unclaimed method, to provide a combination of an open-pore material 31 and a pressure relief body 32, the pressure relief body 32 can be designed and preferably tested for ignition dielectric strength (e.g., according to standard EN 60079-1) independently of the open-pore material 31, in particular without considering the open-pore material 31, and an arrangement of the open-pore material 31 and the pressure relief body 32 can be designed to ensure compliance with a predetermined upper temperature limit of the pressure relief body 32 and / or a housing 10, e.g., according to a temperature class of standard EN / IEC 60079-0. The pressure relief body 32 alone may not be sufficient to achieve the target temperature class. Only with the open-pore material 31 is the target temperature class achieved with the arrangement.The arrangement is designed to possess the necessary heat capacity and / or thermal conductivity to ensure that the peak temperature of the arrangement remains below a predetermined maximum temperature, even when heat is introduced into the arrangement due to an explosion. Using this method, for example, any arrangement of an open-pore material 31 and a pressure relief body 32 described herein can be created. If the open-pore material used is a container structure containing loose particulate material, the design of the arrangement for the elevated temperature class becomes particularly simple.

[0061] In Figures 5a and 5bThe open-pore material 31 and the pressure relief body 32 are each represented as a lattice structure with one or more lattice layers and / or lattice strata. Independently of each other, the open-pore material 31 and / or the pressure relief body 32 can have a structure other than a lattice structure.

[0062] For example, it shows Figure 6 An embodiment with a container structure 41 filled with loose particulate material as an open-pore material 31. The particulate material can be, for example, one as described in connection with the other embodiments. For example, the loose particulate material can be granules, in particular spheres or grains of metal, polymer, glass, and / or ceramic. The particles 39 shown have a uniform size. The targeted use of particles 39 of different sizes is possible. The embodiment according to Figure 6 is in contrast to the according to Figure 5a, 5bFurthermore, it is modified insofar as the open-pored material 31 is arranged in the interior 15 on the opening in which the pressure relief body 32 is arranged.

[0063] The open-pore material 31 can be used to supplement a pressure relief body 32, forming an arrangement of the open-pore material 31 and the pressure relief body 32 that does not meet the requirements for ignition dielectric strength and / or compliance with a maximum temperature of the pressure relief body 32 and / or the housing 10 of the pressure relief body 32 alone. For example, the arrangement of open-pore material 31 and pressure relief body 32 can meet an ignition dielectric strength level or class that the pressure relief body 32 alone does not meet. The pressure relief body 32 can, for example, be designed and preferably tested to meet a specific level or class of ignition dielectric strength, such as IIA or IIB of the IEC 60079-5 standard.The combination of pressure relief body 32 and open-pore material 31 can, for example, be designed to meet the requirements of a higher level or class of ignition breakdown safety, e.g. IIB or IIC of the standard IEC 66079-5.

[0064] This upgrading of a pressure relief body 32 to achieve a higher temperature or ignition breakdown protection class can be achieved by means of in and / or on the opening in which the pressure relief body 32 is arranged - as e.g. in the Figure 1 , 4 , 5a,b, 6, 7 and 8 illustrated.

[0065] Alternatively, the opening, which is provided with a pressure relief element 32, can be free of an open-pore material 31 or only partially covered or filled, with open-pore material 31 being located elsewhere in the interior 15 of the housing 10 (e.g., body 26). Figure 1or is arranged on or in a wall 11-14 of the housing 10 and, due to the open-pore material, a lower specified maximum temperature of the housing 10 and / or the pressure relief body 32 is maintained than without the open-pore material 31. In particular, due to the open-pore material 31, the maximum temperature maintained of the housing 10 and / or the ignition breakdown resistance can be increased by at least one class (grade).

[0066] Not only can a type of pressure relief body 32, designed to comply with a specific flameproof safety level and, if necessary, additionally designed to comply with a specific maximum surface temperature to prevent ignition of an explosive atmosphere on the outer surface according to a safety level, be structurally supplemented with the arrangement using the open-pored material 31 to create an arrangement with a higher flameproof safety level and / or a lower maximum surface temperature, but, in particular, an already manufactured and possibly installed pressure relief body 32 can advantageously be supplemented with a porous material 31 to form any arrangement, as described herein by way of example. This also makes it possible to upgrade an existing housing 10 or an existing pressure relief body 32.

[0067] Exemplary embodiments of a method for providing an arrangement with increased flameproof resistance, by which arrangements with open-pore material 31 and a pressure relief element 32 as described herein can be provided, involve arranging an open-pore material 31 and a flameproof body 32 in a single assembly. The assembly of flameproof body 32 and open-pore material 31 is designed for a higher flameproof resistance than the flameproof body 32 without the open-pore material 31. The flameproof body 32 can be tested for flameproof resistance without the open-pore material 31. The assembly can be subjected to testing for increased flameproof resistance.

[0068] Figure 11Method 100 is illustrated by way of example, wherein in step 101 a body 32 is designed for a specific flameproof resistance or a body 32 with a specific flameproof resistance is provided. In a further step 102 an arrangement of the body 32 and open-pore material 31 is designed to ensure compliance with a maximum temperature (e.g., according to one of the temperature classes T1 to T6) of the flameproof body 32 and / or the housing 10, for whose pressure relief the body 32 serves, or an arrangement of flameproof body 32 and open-pore material 31 is designed for a higher flameproof resistance level than the flameproof body 32. In an additional step 103, the body and the open-pore material 31 are arranged in the assembly.

[0069] Figure 7shows an exemplary embodiment of a section of wall 14 according to an embodiment as per Figure 6In the interior space 15, an open-pore material 31 is arranged in front of the opening in the wall 14, such that gas must pass through the open-pore material before entering the pressure relief body 32. The open-pore material 31 is provided in the form of a container structure 41 filled with loose particulate material. The container structure 41 is divided into two compartments by means of a gas-permeable partition structure 43, which are filled with particles of different sizes. The first compartment, which is filled with smaller particles than the second compartment, covers the second compartment facing the interior space 15. The gas must first pass from the interior space 15 through the first compartment 44, through the partition structure 43, and then through the second compartment 45 before reaching the pressure relief body 32.During the transition from the first compartment 44 to the second compartment 45, the increase in the free volume between the particles 39 in the first compartment 44 relative to the second compartment 45 can lead to additional cooling of the hot explosion gas. The particles in one compartment may differ from the particles in another compartment in one or more other properties, such as composition and / or shape, either in addition to or instead of size. The compartments may have different fill levels.

[0070] Figure 8Figure 1 shows an arrangement consisting of a flame-resistant pressure relief body 32 in an opening in a wall 14. In the opening, between the flame-resistant pressure relief body 32 and the interior 15 of the housing 10, a container structure 41 filled with loose particulate material (open-pore material 31) is arranged, which complements the pressure relief body 32. The container structure 41 can be divided into two or more compartments 44, 45, through which the gas must flow sequentially from the interior 15 to the pressure relief body 32 outside.

[0071] The housing 10 according to the invention is provided internally with a lining of open-pore material comprising at least two sides of the housing 10 to reduce internal explosion pressure. Additionally, a shaped element made of open-pore material can be arranged in the housing. The open-pore material can be, for example, bonded fiber material or loose particulate material containing a container structure 41.

[0072] Based on Figure 9 Further embodiments of a housing 10 according to the invention are illustrated. The housing 10 comprises several walls 11, 12, 13, 14, which enclose an internally enclosed space 15. The walls 11 to 14, together with a base and a lid (not illustrated), form a wall assembly 16. The base and lid of this housing 10 can be fixedly or detachably connected to the walls 11 to 14. They are also considered walls.

[0073] The interior space 15 may contain components such as printed circuit boards, 17, 18 with electrical components arranged on them, which may form ignition sources.

[0074] Open-pore material 19, 20 is arranged on at least two of the walls 11, 12, 13, 14 of the housing 10, covering each wall 11, 12 completely or partially. The open-pore material 19, 20 is formed by a container structure 41 filled with loose particulate material. Features of the container structure 41 and / or the loose particulate material explained in connection with other figures can optionally also be applied to the material in the housing 10 shown in the figures. Figure 9The illustrated embodiments apply. The container structure 41 includes a boundary structure 21, e.g., a lattice structure, which forms at least one container wall 21 separate from the walls 11-14 of the housing that define the interior 15. This container wall 21 allows gas to pass into the interior of the container structure, which is at least partially filled with the loose particulate material and is separated from the remaining interior 15 of the housing 10 by means of the container structure 41. However, the container wall 21 retains the particles 39 ( Figure 10 ) to access the area of ​​the interior 15 that is complementary to the container structure 41. Openings in the container wall 21 are dimensioned accordingly small. The grid structure 21 can be a perforated sheet metal housing, a wire mesh, a cage, or the like.

[0075] The loose particulate material can be arranged directly adjacent to the respective wall 11, 12. Preferably, no particulate material is connected to the wall 11, 12. If the loose particulate material is arranged directly adjacent to the respective wall 11, 12, the respective wall 11, 12 forms part of the container structure 41. Alternatively, the container structure 41 can be composed entirely of boundary structures 21, which are distinct from the walls 11-14 that define the interior 15. These boundary structures 21 can, for example, form a cage that keeps the open-pored material 19, 20 away from the rest of the interior 15 and is preferably connected to the housing 10.

[0076] The grid structure 21 follows the walls 11 and 12 and is thus arranged at a corner. In general, the grid structure 21 can be adapted to the housing shape and / or wall shape of the housing 21, e.g., maintaining a constant distance from the walls 11 and 12 along the wall.

[0077] The open-pore material 19, 20 has surfaces 22, 23 on its side facing the interior 15, which are arranged at an angle to each other as shown, which is less than 180°.

[0078] In addition to the open-pore material 19, 20, a further section 24 of open-pore material is arranged opposite the open-pore material 19. This can be the same or a different open-pore material as materials 19, 20. It can therefore also be formed by a container structure 41 with a boundary structure 21 filled with loose particulate material. It can have the same or a different thickness. Likewise, the open-pore materials 19, 20 can have the same or different thicknesses. Material 24 has a surface 25 facing the interior 15, which is opposite surface 22 and is arranged at an angle of, for example, 90° to surface 23.

[0079] The open-pore material 19, 20 and / or 24 forms an internal pressure relief device. An additional or alternative internal pressure relief device can be formed by an open-pore body 26, as shown in Figure 9 As illustrated by example, the body 26 is arranged in the interior 15 of the housing 10, free on at least four, preferably five or six sides, i.e., not abutting any of the walls of the wall arrangement. The open-pore body 26 is preferably arranged as shown in the illustration. Figure 9As illustrated by way of example, the body 26 is arranged on at least four, preferably five or six sides, not on a wall. Preferably, installation areas are provided between the body 26 and at least four walls, into which electrical components, electrical circuits, or other electrical equipment can be installed or are installed, which may constitute ignition sources. The body 26 may, in particular, be surrounded by electrical components, electrical circuits, or other electrical equipment. The body 26 is preferably gas-permeable through all free sides. The following descriptions of the body 26 also optionally apply to the open-pore material 19, 20, 24.

[0080] Body 26 is, as in Figure 9The container structure 41 is illustrated as being formed from a container structure 41, which is partially filled with loose particulate material. The gas-permeable boundary structures 21 of the container structure 41 separate a compartment of the interior 15 for the filling with loose particulate material. This allows, for example, a bed of spheres to be placed at any desired location within the housing 10. The loose particulate material can be, for example, quartz sand or glass particles. The container structure 41 can contain, for example, a homogeneous mixture of particles 39, which may be heterogeneous with respect to shape, size, and / or composition, or particles 39 of uniform size, shape, and composition. The body 26 is preferably free of electrical equipment, in particular free of electrical components. The body 26 itself has gaps that do not need to be flameproof.The gaps formed by openings in the container structure 41 and the spaces between particles of the loose particulate material filling do not need to conform to a standard dimension, thus ensuring ignition propagation resistance through the gaps. The body 26 serves solely to relieve pressure in the event of an explosion occurring in the interior 15 of the enclosure 10. The enclosure 10, which contains the body 26 and / or the porous material 19, 20, 24, does not need to conform to the type of ignition protection "sand encapsulation" (Ex-q, according to standard IEC 60079-5). Due to the degree of filling, the loose particles in the body 26 can still move relative to one another.

[0081] Two or more bodies 26 can be arranged in the housing 10.

[0082] In the event of an explosion originating from an ignition source between one side of the body 26 and the opposite wall 11, 12, 13, or 14, the pressure wave can, on the one hand, directly impact the porous body 26 and, on the other hand, pass through openings in the confining structure 41, e.g., a cage side, into the porous material bed. The kinetic energy is thereby converted into deformation and / or kinetic energy of the loose particles. These particles transfer this energy to other particles 36 and the container structure 41 through collisions and friction, distributing it within the porous body 26. The pressure wave can, on the other hand, be reflected at the opposite wall 11, 12, 13 or 14, particularly if it is free of porous material, or at the porous material on the wall 11, 12, 13 or 14, towards the porous body 26 and / or a wall opposite the wall and / or a wall arranged at an angle. This wall or...Walls can be free of porous material or covered with porous material. The pressure wave can be reflected from the wall or the porous material to another side of the porous body 26, where it is at least partially absorbed. Even if the ignition source is located between a specific side of the porous body 26 and an opposite wall, the pressure wave can still reach all accessible sides of the porous body 26 through reflection from the walls 11-14 and / or porous material and be absorbed by it. The packing of loose particulate material is therefore shapeless, thus avoiding a strong directional dependence due to the filling of the container structure 41 with the packing when absorbing kinetic energy and / or thermal energy due to the pressure wave by the porous body 26.The shape of the container structure 41 and / or the shape that the container structure 41 gives to the filling is preferably rotationally symmetric on the order of multiples of four or non-discrete rotationally symmetric such that the sides of the porous body 26 or of the filling, respectively, that are shown to the walls 11-14, are of comparable size and shape. The body 26 can, in particular, be centrally located between four in . Figure 9 The walls 11-14 shown are arranged differently from the one shown in Figure 9 The illustrated embodiment may be free of porous material 19, 20, 24.

[0083] The housing 10 is not provided with a pressure relief device 29 and / or 30 that allows a flow connection between the housing interior and the environment. Such devices are not provided in the housing 10 according to... Figure 9The missing pressure relief devices 29, 30, 32 are described in connection with other embodiments of the invention as porous gas-permeable bodies with a gap width and gap length that prevents flame penetration (ignition penetration) (see Figure 1 , 4 , 5a, 5b , 6 , 7 , 8 The housing 10 can, in fact, be pressure-tight.

[0084] The housing 10 according to Figure 9 can be similar to the housing according to Figure 3 be designed and have porous material in the form of one or more container structures 41 filled with loose particulate material on all four walls 11, 12, 13, 14 of the housing 10 and optionally additionally on the base and / or lid (not illustrated).

[0085] The open-pore material of the embodiments, as in connection with the Figures 9 and 10explained, forms a locally interrupted or continuous layer and / or body 26 running along the walls, which captures a flame front ignited in the interior 15 and absorbs the resulting pressure wave. Reference symbol:

[0086] 10 Housing 11 - 14 walls 15 interior 16 Wall arrangement 17, 18 Printed circuit boards, electrical equipment 19, 20 open-pore material 21 Grid structure / boundary structure 22, 23 Surfaces of the open-pored material 24 section of the open-pored material 25 Area 26 open-pored body 27 Fibers 28 binder 29, 30 Pressure relief device 31 open-pore material 32 Pressure relief body 33 Expansion volume 34 Sub-housing 35 Pressure relief body 36 Implementing institution 37 Wave 38 gap 39 Particles of a loose particulate material 40 pore 41 Container structure 42 further boundary structure 43 Division structure 44 First compartment 45 Second compartment

Claims

1. A housing (10), in particular a housing of the ignition protection type flameproof enclosure, having a wall arrangement (16) comprising a plurality of walls (11, 12, 13, 14) which enclose inner space (15) that is closed to the outside, wherein at least two of the walls (11, 12) are provided with an open-pore material (19, 20, 31) in that the latter is attached to the walls (11, 12, 13, 14), characterized in that the open-pore material (19, 20, 31) is bulk particulate material in a gas-permeable container structure (41), wherein the container structure (41) is able to contain a maximum amount of the bulk material, wherein the container structure (41) contains less than the maximum amount of the bulk particulate material, so that the particles of the bulk particulate material can still move relative to each other.

2. The housing (10) according to claim 1, characterized in that the area of the wall (11, 12, 13, 14) supporting the open-pore material (19, 20, 31) comprises at least one opening which is provided with a gas-permeable flameproof body (32).

3. The housing (10) according to anyone of the preceding claims, wherein the open-pore material (19, 20, 31) is arranged in front of the flameproof body (32, 35), preferably in the opening in the wall, such that the explosion front must first pass through the open-pore material (19, 20, 31) before the explosion front passes through the flameproof body (32).

4. The housing (10) according to anyone of the preceding claims, wherein the arrangement comprising the porous material (31) and the flameproof body (32) is configured such that its maximum surface temperature and / or the maximum temperature of housing (10) remains below a predefined temperature by means of the porous material (31), wherein the porous material (31) alone is not configured to be flameproof.

5. The housing (10) according to anyone of the preceding claims, wherein the combination of the flameproof body (32, 35) with the open-pore material (19, 20, 31) arranged in front thereof has a higher flameproof protection class than the flameproof body (32, 35).

6. The housing (10) according to anyone of the preceding claims, wherein the open-pore material (19, 20, 31) is connected to the flameproof body (32, 35) to form one element.

7. The housing (10) according to anyone of the preceding claims, characterized in that the area of the wall (11, 21) supporting the open-pore material (19, 20) is configured in a closed manner or has only flameproof gaps (38).