HOUSING WITH INTERNAL PRESSURE REDUCTION

Abstract

The invention relates to a housing that can be provided on the inside with a lining, made of an open-pore material and preferably covering at least two sides of the housing, for the reduction of internal explosion pressure. In addition or alternatively, a molded body made of the open-pore material, in particular a bonded fiber material, can be arranged in the housing. Methods according to the invention are used to provide an assembly of an open-pore material and a flameproof body in order to create an assembly that has a higher temperature class and / or a higher flameproofing class than those for which the flameproof body is designed.

Description

Explosion-proof housing with internal Pressure reduction process

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

[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 arranged inside it, for example made of slag wool, glass wool, metal, or ceramic with open, continuous pores or gaps. Such a body arranged inside the enclosure This should lead to a reduction in explosion pressure of 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] The 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.

[0007] In contrast, DE 10 2013 109 259 A describes an explosion-proof enclosure of protection type 'pressure-resistant 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. [000S] Such pressure relief bodies are subject to contamination when such housings are arranged in adverse environments, or to microbial growth, icing, and / or corrosion when exposed to the elements. Taking such circumstances into account increases the effort required.

[0009] The purpose of the invention is to provide a concept for an explosion-proof enclosure that is versatile and inexpensive to build.

[0010] This problem is solved with the housing arrangement according to claim 1 as well as with the housing arrangement according to claim 9:

[0011] The housing according to the invention comprises a wall arrangement with several walls enclosing an interior space. At least one of the walls is provided with an open-pored material.

[0012] The open-pore material allows for cooling and thus a significant reduction in gas pressure following an explosion.

[0013] 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.

[0014] 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.

[0015] In preferred embodiments, the flameproof body is designed, alone or at least primarily, and particularly preferably tested (type and / or individual 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. In these embodiments, however, the flameproof body alone can achieve the target temperature class of the surface of the flameproof body.the housing temperature has not yet been reached. Preferably, the combination of open-pore material and flameproof body is arranged so that, in the event of an explosion inside, the surface temperature of the flameproof body and / or the housing remains below a defined maximum temperature. In the embodiments, the arrangement with the open-pore material is located before the... 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) of 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. The stringent requirements regarding the gap size to prevent flame penetration are therefore only applied to the body, not to the open-pore material. In particular, the average ratio of gap width to gap length in the flameproof body can be smaller than in the open-pore material.

[0016] It is also possible that the flame-resistant body alone is designed and preferably tested, in particular type-tested or individually tested, for both ignition flashover protection 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 flame-resistant 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., TI 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 flashover resistant.

[0017] Alternatively or additionally, it is possible that the flameproof body alone is designed and tested for ignition flash resistance of a specific group (e.g., IIA or IIB of standard EN / IEC 60079-1), in particular type-tested or individually tested, and that the arrangement with open-pore material and the flameproof body is designed and preferably tested for a higher group with regard to ignition flash resistance, in particular type-tested or individually tested. 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, to achieve group IIB. Alternatively, for example, the combination may be designed to achieve group IIC based on group IIA or IIB for the flameproof body.The open-pored material alone is preferably not designed to be flameproof.

[0018] In preferred embodiments, the open-pored material enhances the flame-resistant body so that the combination of a stricter requirement (lower maximum temperature) for the maximum surface temperature and / or a stricter requirement for the or a higher class of ignition penetration resistance is satisfied.

[0019] The open-pore material can be bonded to the flame-resistant body to form a single element, e.g., sintered. This allows for the determination of the relative arrangement of the open-pore material and the flame-resistant body prior to their placement on the wall.

[0020] The open-pore material and / or the flame-resistant body may have a grid arrangement, in particular one each. A grid arrangement may, for example, have one or more grid layers or strata. In a grid, two openings of the grid are separated by a web of the respective grid material. The openings may also have a width of zero in some cases. A grid arrangement or a grid layer or strata may have a woven or non-woven fabric of fibers or wires.

[0021] According to an inventive concept for the simple and modular construction of an open-pore material, the open-pore material can be formed with loose particulate material in 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. By means of the boundary structure, a space for the particulate material is separated from the interior of the housing. The boundary structure can, for example, be formed by a grid arrangement. The boundary structure can be formed by a woven fabric or a non-woven fabric. In embodiments, the flame-resistant body can form part of the container structure by forming a barrier for the loose particulate material.In other embodiments, the limiting structures of the container structure are separate from the flame-resistant body.

[0022] The loose particulate material can, for example, be spheres, especially hollow spheres or spheres which do not Enclose a cavity, contain 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.

[0023] 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.

[0024] The loose particulate material can have a selected average particle size and / or a selected particle size distribution. In particular, the container structure can feature a targeted mixture of differently sized particles.

[0025] The container structure can hold a maximum quantity, particularly with regard to the average particle size and / or the size distribution of the bulk material, i.e., the loose particulate material. In some embodiments, the container structure can hold less than the maximum quantity of the loose material. Contains particulate material, so the fill level can be less than 1.

[0026] 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 a design 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., located between the ignition source and one or more other compartments. This first compartment can, for example, be designed with regard to...The bulk material density of the first compartment is optimized for kinetic energy conversion, while the downstream bulk material is optimized for cooling. The downstream bulk material can, 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 can 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.

[0027] 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 a pressure front of an explosion can be transferred to the particles, and this energy can be passed from particle to particle through collisions and / or friction.

[0028] In some embodiments, 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 completely 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.

[0029] The use of at least two or more wall surfaces for the application of open-pore material that dampens a pressure wave impacting or traveling along it results in a large active damping area and thus a high damping effect, even if only relatively thin layers of open-pore material are used, where the thickness of the layer is, for example, less than The gap between opposing walls can be one-tenth or one-twentieth of the housing's internal diameter. This means that the available interior space for components is only slightly reduced by the open-pore material. The housing walls can be partially or completely lined with this open-pore material. The open-pore material acts both as a non-ignitable venting volume and as a quenching 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, also lowers the pressure.By completely lining the inside of the housing with the open-pore material, an optimal surface area to volume ratio is achieved for the housing.

[0030] By arranging the open-pored material, preferably exclusively on the walls, a large, contiguous installation space is obtained for equipment, switches, and the like.

[0031] 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.

[0032] The open-pore material can be fully bonded, either material-bonded or only partially bonded to the walls of the pressure-resistant housing. This can be achieved by welding the porous material to the walls or, if the housing is manufactured using a casting process, by inserting it into the mold and forming it into the housing walls. Other mechanical, form-fitting, and / or material-bonded connection methods can also be used. For example, the open-pore material can be enclosed by a grid structure that is connected to the wall assembly. This grid structure can be a wire mesh, a perforated sheet, a plastic mesh, or similar material.

[0033] The open-pore material can have a surface facing away from the wall on each of the walls to which it is attached, and oriented towards the interior. This surface can be parallel to the wall or at an acute angle to it. The porous material can be designed as a panel, mat, or filling of essentially constant thickness, so that the surface facing away from the wall is either parallel to or at an acute angle to the wall. This ensures that at least two surfaces of the open-pore material are essentially opposite or at an angle to each other in the interior. Both configurations result in effective damping of a dynamically propagating flame front.

[0034] Pressure relief elements can be installed in areas of the wall free of open-pore material or in areas of the wall covered by open-pore material. While the open-pore material itself does not provide protection against Flame penetration protection is provided, or must be provided, by the pressure relief element(s). The open-pore material primarily serves to cool the gas, thus absorbing heat energy and reducing pressure peaks. With respect to the gas flow, the heat absorption element formed by the open-pore material and the flame arrestor are arranged one behind the other. 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 to the inside of a single housing wall or to multiple housing walls.

[0035] 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. 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, can be formed from several superimposed layers of the grid, mesh, or woven structure. These layers can lie loosely on top of each other or be bonded together, for example, by sintering or by another technique.The bodies made of wire or fiber material can be needle-felted arrangements, i.e. A tangled fiber fabric consists of matted fibers that are not physically bonded to one another. If necessary, the fibers may also be physically bonded to each other, 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.

[0036] The fibrous material of the open-pore structure 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 in place by a frame. The density of the fibrous body is preferably so low, however, that the gaps and spaces within the porous material are, at least in some places, above the limiting gap width of a conventional explosion-proof enclosure. This means that cooling effects, flow effects, or other kinetic effects that could prevent the ignition of gas present in the material or the passage of the flame front through the material are either absent or incomplete. Particularly when the open-pore material has a high heat capacity, as is the case, for example, with glass fibers, quartz fibers, ceramic fibers, or mineral fibers, a high pressure reduction is still achieved.

[0037] 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 created. This does not necessarily have to be in contact with the wall. Alternatively or additionally, an open-pored, dimensionally stable body can be made of a container structure that is wholly or partially filled with loose particulate material. Such a pre-formed, bonded fibrous body, or a body containing bulk material, can also be arranged within the housing, accessible from four, five, or six sides. It acts as a pressure-reducing element even without a wall connection and can be used as an alternative or in addition to the housing linings with open-pore material described above. The open-pore material arranged on the housing wall can also be stabilized in its shape by an organic or inorganic binder. 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 bonded to one another in a cohesive manner, in order to obtain 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.

[0038] Using a method according to the invention, an arrangement consisting of a porous material and a flame-resistant body can be provided. The flame-resistant body is designed and preferably tested for a specific gas group with regard to preventing ignition breakthrough, independently of the porous material. For example, according to one of groups IIA, IIB, or IIC as defined in standard EN / IEC 60079-1. To ensure compliance with an upper temperature limit for the flame-resistant body and / or a housing to which the body is fitted, the arrangement of the porous material and the body is designed accordingly.

[0039] In a further method according to the invention for providing a device with increased flameproof protection, open-pore material is arranged on a body which body is designed for flameproof protection of a specific 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 protection than the flameproof body.

[0040] Further features and embodiments of the invention will become apparent from the claims, the drawing, and the following description. These show:

[0041] Figure 1 shows a housing according to the invention with various measures for pressure reduction, in a schematic representation;

[0042] Figure 2 shows a section of a pressure-reducing, open-pore body of the housing according to Figure 1;

[0043] Figures 3a and 4 show further embodiments of the housing according to the invention, each in a schematic cross-sectional view.

[0044] Figure 3b shows a section of an open-pore material of the housing according to Figure 3a.

[0045] Figure 5a shows another embodiment of a housing according to the invention,

[0046] Figure 5b shows a section of the housing according to Figure 5a,

[0047] Figure 6 shows a section of a housing in a further embodiment,

[0048] Figure 7 shows a section of a housing in an embodiment modified from Figure 7.

[0049] Figure 8 shows a section of a housing in a further embodiment,

[0050] Figure 9 shows a section of a housing of a further embodiment,

[0051] Figure 10 shows a section of a pressure-reducing, open-pore body of the housing according to Figure 9 and

[0052] Figure 11 is a diagram illustrating inventive processes.

[0053] Figure 1 illustrates an explosion-proof enclosure 10 comprising several walls 11, 12, 13, 14 that define an internally sealed space 15. The walls 11 to 14, together with a base and a lid (not shown), form a Wall arrangement 16. The base and lid of this enclosure can be permanently or detachably connected to walls 11 to 14. They are still also considered walls.

[0054] The interior space 15 can contain components and elements such as printed circuit boards, 17, 18 with electrical components arranged on them, which can form ignition sources.

[0055] 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 can comprise fibers or particles in movable form or in interconnected form. It can contain regularly or irregularly formed and arranged pores. For example, 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 interconnected or lie loosely on top of each other, e.g., in layers. The metal wires, strips, or wires can also be formed into another type of mesh, such as a knitted or woven fabric. The wires, ropes, or strips can also consist of another heat-absorbing material.

[0056] 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. Alternatively or additionally, the open-pore material 19, 20 can be 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 can be filled with loose particulate material, whereby the fill level can be 1 or less.A high degree of filling may be necessary, for example, in an embodiment 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 first to reach the pressure relief element. A lower degree of filling may suffice for an open-pore material that is arranged in a closed area of ​​a wall or is accessible from one, two, ..., or six sides within the interior. The loose particulate material can be regular, for example, spherical, or irregular, 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, expanded metal granules, foam spheres / bodies, fiber spheres / bodies, or... Other bulk materials can be used. 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 wall 11, 12 along the wall.

[0057] The open-pored material 19, 20 has surfaces 22 on its respective side facing the interior 15. 23, which are arranged at an angle to each other as shown, which is less than 180°.

[0058] Alternatively or additionally 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.

[0059] 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 resting against any of the walls of the wall assembly. The following explanations of body 26 also apply optionally to the open-pore material 19, 20.

[0060] The open-pore body 26 can be a fibrous body whose fibers are bonded together by a binder. Figure 2 schematically illustrates a section of the body 26. As can be seen, several fibers 27 are intertwined in a spatially disordered arrangement and bonded at least some of their intersections by a binder 28. The fibers can be metal fibers or mineral fibers, in particular glass fibers, quartz fibers, rock fibers, or ceramic fibers. The binder 28 can be a synthetic resin, in particular a phenolic resin. The resin content is so small that the pores between the fibers 27 remain open. However, it is large enough that the open-pore body 26 has considerable dimensional stability, so that it is not disintegrated when an explosion is ignited in the interior 15 and releases as few fibers as possible, or at most a harmless quantity.

[0061] Alternatively, the fibers, wires, threads, or particles of which the body 26 consists can also be arranged regularly and yet be 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.

[0062] The body 26 can alternatively be formed by a container structure which is wholly or partially filled with preferably loose particulate material. A gas-permeable boundary structure within the container separates a compartment of the interior for the loose particulate material filling. This allows, for example, a granular packing to be placed anywhere within the enclosure. The loose particulate material can be, for example, quartz sand or glass particles. The enclosure is preferably free of electrical equipment, especially electrical components. The enclosure itself has gaps that 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 conform to any standard dimensions, thus ensuring flameproofness through the gaps. The enclosure serves solely to reduce pressure in the event of an explosion inside the enclosure. The enclosure does not need to comply with the "sand encapsulation" (Ex-q, according to IEC 60079-5) type of protection.In the body 26, the loose particles can still move against each other due to the degree of filling, or the container structure 41 is so full of loose particles that they cannot move against each other.

[0063] 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 additional- The pressure relief device 30, either as provided or as an alternative, is covered by the open-pored material 25 as seen from the interior 15. This material does not, however, prevent gas from passing through. This combination of heat-absorbing, open-pored, but not flame-resistant material 25 and the pressure relief device 30 can be used independently of the open-pored material 19, 20.

[0064] Figure 3a 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 according to Figure 3 has porous material 19, 20, 25, 31 on all four walls 11. 12, 13, 14 of the housing and optionally also on the base (not illustrated) and / or the lid. The open-pore material 19, 20, 25, 31 forms a locally interrupted or continuous layer running along the walls, which captures a flame front ignited in the interior 15 and absorbs the resulting pressure wave.

[0065] Figure 3a illustrates an embodiment of the open-pore material 31 as a container structure, formed by the walls 11, 12, 13, 14 and a temperature-stable additional boundary structure 21, and containing a loose particulate material 39, wherein interconnected spaces between the particles form open pores 40 and thus give the material 31 the ability to allow gas to pass into the interior of the material 31 and / or through the material 31. The particles 39 in the open-pore material 31 of any embodiment They can have a uniform size or, as shown, different diameters. The particles 39 can have a selected size distribution that differs from a uniform size distribution.

[0066] The additional boundary structure 21 can be, for example, a grid structure in the form of a wire mesh, perforated sheet, plastic grid, 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 open-pored material 31 via the pores. 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—apart from 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.

[0067] 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 are less compressed when a pressure front impacts the open-pore material. The material remains open, whereas with an elastic, flexible, open-pored material there is a risk that, especially when the pressure front hits the material, the pores will close and the gas exchange through the material will be impaired.

[0068] The particles, which are preferably 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. Particles freely moving relative to each other in a container structure filled to a fill level 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. Alternatively, the container structure 41 of an open-pore body (e.g., body 26 in Figure 1) or open-pore material can be filled in such a way that the particles cannot move relative to each other.

[0069] The housing 10 illustrated in Figure 4 is an embodiment based on the housing 10 of Figure 3a. 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 expansion volume 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 can be made of an open-pore material containing a container structure with loose particulate matter. exhibit material as described, for example, in connection with Figure 3.

[0070] Additionally or alternatively, a pressure relief element 35 can be provided in the wall 12, enabling pressure relief to the surroundings. 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.

[0071] Figure 5a shows an embodiment of a housing 10 according to the invention with an electrical device 17 located therein. As shown, only one wall 14 of the housing is provided with a gas-permeable porous material 31, in which the device is arranged wholly (as shown) or partially (projecting into the interior 15 of the housing 10) in an opening of the wall 14 of the housing (see also the enlarged view of the Figure 5a (detail shown in Figure 5b). Other walls 12-14 of the housing 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 housing, such that the open-pored, gas-permeable material 31 completely covers the pressure relief body 32 against the interior 15, but allows gas to pass through. In order to pass through the pressure relief body from the interior 15 of the housing 10 into the surroundings of the housing 10, the gas must first flow through the open-pored material 31.

[0072] 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 flameproofing. The type (type test) of the pressure relief body 32 can be tested without the open-pore material 31 of the type shown in Figure 5a arranged upstream, or the specific pressure relief body 32 can be tested without the open-pore body 31 specifically shown in Figure 5a arranged upstream (individual test).However, the pressure relief body 32 cannot be specifically designed or suitable to ensure, 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 which is not sufficient for the thermal ignition of a specific. Gas is present on the outside of the housing 10. The pressure relief element 32, in particular, cannot be designed or suitable to meet a specific temperature class of standard EN / IEC 60079-0. Rather, the combined arrangement of porous material 31 and pressure relief element 32 – in which the porous material and the pressure relief element 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 element 32 is therefore preferably designed to meet a specific temperature class, for example, standard EN / IEC 60079-0. This is especially true when the pressure relief element 32 is connected to, for example, a gas, in the housing 10.In the case of sintered, porous material 31, one can speak of two connected segments of an element. However, in embodiments, the design for ignition penetration resistance 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.

[0073] According to a method according to the invention, 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 taking open-pore material 31 into account, and an arrangement of the open-pore material 31 and the pressure relief body 32 can be used to ensure The design is intended to ensure compliance with a predetermined upper temperature limit for 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. The target temperature class is only achieved with the addition of the open-pore material 31. 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 in the event of heat input 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 loose particulate material containing a container structure is used as the open-pore material, the design of the arrangement for the increased temperature class becomes particularly easy.

[0074] In Figures 5a and 5b, the open-pore material 31 and the pressure relief body 32 are each depicted 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.

[0075] For example, Figure 6 shows 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 of those described in connection with the other embodiments. For example, the loose particulate material can be granules, in particular from spheres or granules 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 also modified compared to that according to Figures 5a, 5b in that the open-pored material 31 is arranged in the interior 15 on the opening in which the pressure relief element 32 is arranged.

[0076] 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 alone 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. 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.

[0077] This upgrading of a pressure relief body 32 to achieve a higher temperature or ignition flashover protection class can be carried out with in and / or on the opening, in which of the pressure relief body 32 is arranged, it can be illustrated - as e.g. in Figures 1, 4, 5a, b, 6, 7 and 8.

[0078] 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 1 or 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 maintained maximum temperature of the housing 10 and / or the ignition breakdown resistance can be increased by at least one class (grade).

[0079] Not only can a type of pressure relief body 32, which is designed to comply with a specific flameproof safety level and which may additionally be designed to comply with a specific maximum surface temperature to prevent ignition of explosive atmospheres on the outer surface according to a safety level, be structurally supplemented with the arrangement with 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, a pressure relief body 32 that has already been manufactured and possibly installed can advantageously be combined with a porous material 31 to form any arrangement, as described herein by way of example. can be added. This also makes it possible to upgrade an existing housing 10 or an existing pressure relief body 32. [00S0] Exemplary embodiments of a method according to the invention for providing an arrangement with increased flameproof resistance, by which arrangements with open-pore material 31 and a pressure relief body 32 can be provided as described herein, feature the arrangement of an open-pore material 31 and a flameproof body 32 in an arrangement. The arrangement 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 arrangement can be subjected to a test for increased flameproof resistance.

[0081] Figure 11 illustrates the inventive method 100 by way of example, wherein in a step 101 a body 32 is designed for a specific ignition dielectric strength or a body 32 with a specific ignition dielectric strength 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 TI to T6) of the flameproof body 32 and / or the housing 10, for whose pressure relief the body 32 serves, or an arrangement of ignition-resistant body 32 and open-pore material 31 is designed. The open-pore material 31 is designed for a higher level of ignition penetration resistance than the ignition-penetration-resistant body 32. In an additional step 103, the body and the open-pore material 31 are arranged in the assembly.

[0082] Figure 7 shows an embodiment of a section of wall 14 corresponding to an embodiment according to Figure 6, wherein open-pored material 31 is arranged in the interior space 15 in front of the opening in wall 14, so that gas must pass through the open-pored material before entering the pressure relief body 32. The open-pored 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 from 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 it reaches 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, besides size, e.g., composition and / or shape. The compartments may have different fill levels.

[0083] Figure 8 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.

[0084] The housing 10 according to the invention can be provided internally with a lining of open-pore material comprising one or preferably at least two sides of the housing 10 to reduce internal explosion pressure. Additionally or alternatively, a shaped element made of open-pore material can be arranged in the housing. The open-pore material can, for example, be bonded fiber material or loose particulate material containing a container structure 41.

[0085] Figure 9 illustrates further embodiments of a housing 10 according to the invention. The housing 10 comprises several walls 11, 12, 13, 14, which enclose an interior space 15 that is sealed off from the outside. 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 enclosure 10 can be permanently or detachably connected to the walls 11 to 14. They are also considered walls.

[0086] The interior space 15 can contain components and elements such as printed circuit boards, 17, 18 with electrical components arranged on them, which can form ignition sources.

[0087] Open-pore material 19, 20 is arranged on at least one of the walls 11, 12, 13, 14, preferably on at least two walls 11, 12, of the housing 10, covering the respective wall 11, 12 completely or partially. The open-pore material 19, 20 can be 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 apply to the housing 10 in the embodiments illustrated with reference to Figure 9. The container structure 41 includes a boundary structure 21, e.g., a grid structure, which forms at least one container wall 21 separate from the walls 11-14 of the housing that define the interior space 15.This container wall 21 allows gas to pass into the interior of the container structure, which is at least partially filled with loose particulate material and separated from the remaining interior 15 of the housing 10 by the container structure 41. However, the container wall 21 prevents the particles 39 (Figure 10) from entering the area of ​​the interior 15 that is complementary to the container structure 41. Openings in the container wall 21 are correspondingly small. The grid structure 21 can be a perforated metal housing, a wire mesh, a cage, or the like.

[0088] The loose particulate material can be arranged directly adjacent to the respective wall 11, 12. Prior to this, no particulate material is connected to the wall 11, 12. connected. 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.

[0089] 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 to the walls 11 and 12 along the wall.

[0090] The open-pored material 19, 20 has surfaces 22 on its respective side facing the interior 15. 23, which are arranged at an angle to each other as shown, which is less than 180°.

[0091] Alternatively or additionally 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 facing the interior 15. 25, which is opposite surface 22 and is arranged at an angle of, for example, 90° to surface 23.

[0092] 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 illustrated by way of example in Figure 9, 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. Preferably, the open-pore body 26, as illustrated by way of example in Figure 9, is not abutting any wall on at least four, preferably five or six, sides. 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 can be surrounded, in particular, by electrical components, electrical circuits, or other electrical operating 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.

[0093] The body 26, as illustrated in Figure 9, is formed from a container structure 41 which is wholly or partially filled with loose particulate material. The gas-permeable boundary structures 21 of the container The substructure 41 separates a compartment of the interior 15 for filling with loose particulate material. This allows, for example, a packing of spheres to be placed at any desired location within the space. 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 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 26 serves solely to reduce pressure in the event of an explosion occurring in the interior 15 of the housing 10.The enclosure 10, which comprises the body 26 and / or the porous material 19, 20, 24, does not need to comply with the type of protection "sand encapsulation" (Ex-q, according to standard IEC 60079-5). Due to the degree of filling, the loose particles in the body 26 may still be able to move relative to one another, or the container structure 41 may be so full of loose particles that they cannot move relative to one another. Two or more bodies 26 may be arranged in the enclosure 10.

[0094] In the event of an explosion originating from an ignition source between one side of the body 26 and the opposing 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. The pressure wave is then transferred by impacts and friction to other particles 36 and the container structure 41, distributing them 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 by 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. These wall(s) can also be free of porous material or be provided with porous material. From the wall or the porous material, the pressure wave can be reflected 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 at 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 imparts to the packing 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 packing that face the walls 11-14 are of comparable size and shape.The body 26 can in particular be arranged centrally between four walls 11-14 shown in Figure 9, which differ from the one in. The embodiment shown in Figure 9 can be free of porous material 19, 20, 24.

[0095] The housing 10 is not provided with a pressure relief device 29 and / or 30 that would allow flow between the interior of the housing and the environment. Such pressure relief devices 29, 30, 32, which are missing in the housing 10 according to Figure 9, are described in connection with other embodiments of the invention as porous, gas-permeable bodies with a gap width and length that prevents flame propagation (ignition propagation) (see Figures 1, 4, 5a, 5b, 6, 7, 8). The housing 10 can, in fact, be pressure-tight.

[0096] The housing 10 according to Figure 9 can be designed similarly to the housing according to Figure 3 and can contain 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 the lid not illustrated.

[0097] The open-pore material of the embodiments, as explained in connection with Figures 9 and 10, forms a locally interrupted or continuous layer and / or body 26 running along the walls, which catches a flame front ignited in the interior 15 and absorbs the resulting pressure wave. Reference symbol:

Claims

Patent claims:

1. Housing (10), in particular housing of protection type flameproof enclosure with a wall arrangement (16) having several walls (11, 12, 13, 14) enclosing an interior space (15), wherein at least one of the walls (11, 12) is provided with an open-pore material (19, 20).

2. 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) has at least one opening which is provided with a gas-permeable flame-resistant body (32).

3. Housing (10) according to one of the preceding claims, wherein the open-pore material (19, 20, 31) is arranged in front of the flame-resistant body (32, 35), preferably in the opening in the wall, so that the explosion front must first pass through the open-pore material (19, 20, 31) before the explosion front passes through the flame-resistant body (32).

4. Housing (10) according to any of the preceding claims, wherein the arrangement with the porous material (31) and the flameproof body (32) is designed such that its maximum surface temperature and / or the maximum temperature of the housing (10) remains below a specified temperature with the aid of the porous material (31), wherein the porous material (31) alone is not designed to be flameproof.

5. Housing (10) according to one of the preceding claims, wherein the combination of flameproof body (32, 35) with the open-pore material (19, 20, 31) arranged in front of it has a higher ignition penetration protection class than the flameproof body (32, 35).

6. Housing (10) according to one of the preceding claims, wherein the open-pore material (19, 20, 31) is combined with the flame-resistant body (32, 35) to form an element.

7. Housing (10) according to any of the preceding claims, wherein the open-pore material (31) and the flame-resistant body (32) each have a grid arrangement.

8. Housing (10) according to one of the preceding claims, wherein the open-pore material (31) is formed from a grid arrangement.

9. Housing (10) according to one of the preceding claims with loose particulate material in a gas-permeable container structure (41) as open-pore material (19, 20, 31) .

10. Housing according to claim 9 with a container structure (41) for loose particulate material, wherein the container structure (41) can hold a maximum amount of the bulk material, wherein the container structure (41) contains less than the maximum amount of loose particulate material.

11. Housing (10) according to one of the preceding claims, characterized in that the area of ​​the wall (11, 21) supporting the open-pore material (19, 20) is designed to be closed or has only flame-resistant gaps (38).

12. Housing with a wall arrangement (16) enclosing an interior space (15), wherein loose particulate material is arranged as an open-pore body (26) in the interior space (15) containing a container structure (41).

13. Method (100) for providing an arrangement of a porous material (31) and a flame-resistant body (32), wherein the flame-resistant body (32) is designed for a specific ignition dielectric strength independently of the porous material (31), and wherein an arrangement of the porous material (31) and the flame-resistant body (32) is designed to ensure compliance with a maximum temperature of the flame-resistant body (32) and / or a housing (10).

14. Method (100) for providing a device having an increased level of flameproof safety by arranging an open-pore material (31) and a flameproof body (32) in an arrangement, wherein the arrangement of flameproof body (32) and open-pore material (31) is designed for a higher level of flameproof safety than the flameproof body.