RU2794574C2 - Pressure release device, method for its manufacture and explosion-proof casing supplied with them - Google Patents

Abstract

FIELD: pressure release device.

SUBSTANCE: proposed pressure release device (15) comprises a gas-permeable element (17), on which a membrane (21) is stuck, which is preferably made waterproof, while the membrane (21) can be a single or multilayer rubber membrane, which is made by applying a liquid rubber on the pressure relief element (17) and, if necessary, the supporting part (16) framing it.

EFFECT: pressure release device.

14 cl, 7 dwg

Description

The invention relates to a pressure relief device and to a housing with such a pressure relief device. First of all, the invention relates to explosion-proof housings with the type of protection "explosion-proof enclosure", which is designated as type of protection ex-d.

"Flameproof" enclosures often have a so-called pressure relief device, through which the overpressure that has developed in the enclosure can escape to the atmosphere. Such pressure relief devices usually have a porous gas-permeable element, which, although gas-permeable, prevents the passage of flame or incandescent particles. due to the narrowness and length of the pores penetrating it.

From DE 102010016782 A1 a pressure relief device is known with such a porous element having a first side directed towards the internal cavity of the housing and a second side facing the environment. The pressure relief device furthermore has a membrane which is located between the environment and the second side of the pressure relief element in order to keep dust and moisture out of the pressure relief element. In this way, it is to be prevented that the pores of the pressure relief element become filled with dust, moisture leads to degradation, mold or other damage, or biological deposits are formed that can adversely affect the function or are at least unaesthetic. If an explosion is initiated in the housing and the gas flow passes through the pressure relief element, the membrane ruptures and opens the way to the environment. The membrane is provided with a cuff along the edges and by means of it is held on the branch pipe of the pressure relief device. If the membrane is destroyed, it must be replaced, which requires the cuff to be connected to a pressure relief device in a detachable manner. As a result, unintentional removal of the membrane from the pressure relief device may occur. In addition, the membrane can be torn or damaged by external influences, for example, when an object presses on the membrane.

The objective of the invention is to provide a simplified pressure relief device.

This problem is solved by means of a pressure relief device according to claim 1 of the claims and a housing according to claim 12 of the claims. In addition, the method according to claim 13 of the claims provides an expedient arrangement of the membrane on the pressure relief device.

The pressure release device according to the invention comprises: a porous gas-permeable element having a first side, when used, facing a volume containing at least one potential source of explosion initiation, and a second side, when used, facing away from the specified volume, and a membrane located adjacent to the porous gas-permeable element, wherein the membrane is made multilayer and contains a film adjacent to the porous gas-permeable element, which is paper, synthetic film, metal foil, composite film, composite material of plastic and metal or fabric.

Such a porous gas-permeable element is located at the gas outlet, through which gas from an expanding volume, for example, due to an explosion, can enter the atmosphere or into the trapping volume. On the downstream side of the porous gas permeable element, which faces the environment, there is a membrane adjacent to the porous element. This membrane closes the pores of the gas permeable element so that dirt and moisture from the outside do not enter the porous gas permeable element. Due to the contact of the membrane with the porous element, the latter supports the membrane, so that the membrane is protected against impact and similar external loads.

Preferably, the membrane is located on the porous gas permeable element with adhesion, and the adhesion is at least so strong that the membrane does not separate from the porous gas permeable element under pressure drops, such as occur in proper operation. This ensures that the membrane protection provided by the support on the porous gas-permeable element is permanently maintained.

The membrane can preferably adhere to the porous element at least in some places and at least so firmly that it does not uncontrollably lose or separate from the porous gas-permeable element during the intended service life of the pressure relief device. However, the adhesion, on the other hand, is preferably so weak that it separates from the porous gas-permeable element when there is a pressure drop across it that exceeds the negligible pressure drop that occurs during normal operation. During normal operation, small pressure drops may occur when the housing on which the pressure relief device is located experiences heating or cooling due to operating conditions.

The pressure drop leading to separation of the membrane from the porous gas-permeable element is preferably in any case less than the pressure drop leading to damage, deformation or destruction of the attached body. For example, the pressure drop may be less than 5 bar, 3 bar, 1 bar, several hundred millibars, or less than 100 mbar. Adhesion of the membrane to the porous element may be based on adhesion and/or positive engagement of the membrane with the surface roughness or pores of the porous gas permeable element.

Preferably, the adhesive strength of the membrane on the porous gas permeable element is less than the tensile strength of the membrane. As a result, a wide separation of the membrane from the porous gas permeable element can be achieved by means of the gas flow passing through the porous gas permeable element, so that the membrane is completely blown away in the event of an explosion and frees the porous gas permeable element over the entire cross section for the gas flow.

Preferably, the membrane is moisture-impermeable and comprises a film which is disposed on the porous gas permeable element in a releasably adhesive manner. The membrane can be made on a porous gas permeable element by primary shaping. It can also be prepared in a prefabricated form, for example as a film sheet, and positioned adheringly on the porous gas permeable member and optionally on the part connected to it. The film on the side facing the porous element can be provided with an adhesion improver. The film may also be a flexible self-adhesive film. The porous gas-permeable element is preferably flat or simply convex, such as, for example, cylindrically convex. It may also have several mutually parallel faces. The film may also be a shrink film. In this case, it is particularly suitable for application to a porous gas-permeable element, which is made three-dimensional, for example, spherically convex.

Suitable film materials are, in principle, all elastomers and polymers or other plastics, as well as mixtures of them, which can be applied to the porous gas-permeable element in uncured or incompletely cured form, whether in pasty or liquid form, without that the uncured material penetrates, clogging, into the pores of the porous gas permeable element. To ensure this, the porous gas permeable element may be provided with a wetting-impeding agent before the membrane is applied, for example, before the membrane is sprayed, a separating agent, such as oil, oil slurry, silicone, silicone slurry, or the like, may be sprayed or otherwise applied to the surface of the porous gas permeable element to be sprayed. P.

After the membrane material has been applied to the porous gas-permeable element and, if necessary, to the region of the carrier or its surroundings, the membrane material is dried. Drying can take place by ventilating volatile solvents and/or by forming a network and thus curing the precursor material. The formation of a network structure can itself be caused by the passage of time or by means of correspondingly network-inducing influences. Such influences may be the effect on the membrane material of air, moisture, heat, radiation, light, or exposure to chemicals that are contained in the membrane material or applied to the membrane.

The membrane can be made single-layer or multilayer. In the simplest case, the membrane is a rubber or elastomeric membrane sprayed onto a porous gas-permeable element from a material that is used, for example, in the field of car bodies, as a spray film. Such material is sprayed onto the porous gas-permeable element from the outside and "dried", whereby the sprayed material forms the desired membrane.

As mentioned above, the membrane is made multilayer and contains a film that is adjacent to the porous element part of the surface or the entire surface. In the manufacture of a membrane, for example, this film, which may be paper, synthetic film, metal foil, cloth, plastic-metal composite, is applied to a porous gas-permeable member and such a device is then sprayed with the still-liquid membrane material. Such an arrangement facilitates the separation of the membrane from the porous gas-permeable element and enables the use of the scheme according to the invention when already particularly low pressure drops are to lead to separation of the membrane or when a particularly low diffusion permeability is required.

The membrane may contain, in addition to the film, a layer of rubber sprayed onto the film in a liquid state and then cured.

The scheme according to the invention can be applied to mold pressure relief elements formed in a substantially arbitrary manner. They can be designed as three-dimensional elements, such as cylinders, spheres, pyramids, polyhedrons, or, if necessary, as flat elements. Due to this, the circuit according to the invention opens up a wide field for applications that have hitherto not been possible to obtain economically and structurally.

The membrane may extend in sections along the element-bearing part and be positioned adheringly thereon. Such a part can be, for example, a housing wall on which a porous gas-permeable element is located. Particularly large pressure relief elements, which, when viewed from the outside, are located behind the flow-guiding grid, can also be provided with a membrane by spraying membrane material.

The membrane may contain functional elements that, for example, control the integrity of the membrane or other actual circumstances. This happens when conductors, temperature sensors, pressure sensors, or the like are introduced into the membrane. For example, a multi-layer membrane construction can serve this purpose, for example, first spraying a first layer of curable material onto a porous gas permeable element, then positioning the functional elements, and then spraying another layer of setting and/or drying material. Such multilayer structures can be used to detect separation and rupture of the membrane and from them to generate, for example, a signal transmitted to the control point.

Other variants of the invention are possible. Structural forms of the invention follow from the drawing, claims and description. Shown on:

fig. 1 - a housing with a pressure relief device according to the invention, a schematic perspective view,

fig. 2 is a housing pressure relief device according to FIG. 1, in vertical section,

fig. 3 is a fragment of the pressure relief device according to FIG. 2,

fig. 4 - a modified structural form of the pressure relief device on the body, in a vertical section,

fig. 5 - modified structural form of the pressure relief element with a membrane and an additional functional element,

fig. 6 - pressure relief device according to the invention, fragmentary image with high magnification,

fig. 7 is a modified structural form of the pressure relief device in a section similar to FIG. 6.

In FIG. 1 shows the housing 10 in a partially opened form in perspective, enclosing the internal cavity 11, in which the symbolically shown components 12, 13 can be placed there, which, during operation, for example, due to heat generation, sparking, radiation or other influences, serve as sources of initiation explosion (sources of ignition). The housing 10 separates such sources 12, 13 of initiating an explosion from the environment 14 to prevent the spread of flames or explosions occurring in the internal cavity 11 to the environment 12. Preferably, the housing 10 is a housing with the type of protection "flameproof" ). First of all, however, in order to enable rapid equalization of the pressure in the event of an explosion occurring in the internal cavity, and thus a rapid release of the overpressure that has developed in the housing 10, a pressure relief device 15 is provided, which in FIG. 1 is shown on the side of the body 10, purely by way of example. However, the pressure relief device 15 may also be located on any other surface of the housing 10. Also, the housing 10 may have several such pressure relief devices 15 of the same or different size.

In the example, the pressure relief device 15 operates between the internal cavity 11 and the environment 14. However, the pressure relief device 15 may equally well be located between the internal cavity 11 and an outwardly closed pressure relief volume that is temporarily or permanently separated from the environment 14. In its In turn, the pressure relief volume can be provided with a pressure relief device.

The design of the pressure relief device follows more precisely from FIG. 2 and 3. According to them, the housing wall forms a part 16, on which the pressure relief element 17 is directly or indirectly fixed. In this embodiment, the pressure relief element 17 is welded to the part 16, and between the part 16 and the porous element 17 there is an annular weld 18 extending along its perimeter. However, all other possibilities for connecting the housing wall forming the part 16 with the pressure relief element 17 are suitable . For example, the pressure relief element 17 may be located in the cage, which, in turn, is connected, for example, screwed, welded, glued or otherwise fixed thereto, with the part 16. Also, the pressure relief element 17, if the housing 10 is made by casting or in another way of the initial shaping, for example, by additive technology, can be edged into part 16, that is, into the body wall.

In this embodiment, the pressure relief element 17 is located on the pressure relief hole 19, through which the internal cavity 11 is connected to the environment 14. This pressure relief hole 19 may have any suitable shape, for example, a rectangular or square shape with sharp or rounded corners, oval shape, circle shape, or any other suitable shape. Also, the porous gas-permeable element 17 can itself occupy the entire said surface of the wall of the housing 10, that is, itself form a wall or itself occupy several walls.

In an embodiment, the pressure relief hole is divided into several separate holes by grate 20, as shown in FIG. 1 dotted line. The grate 20 can serve to divide the gas flow passing through the porous gas permeable element 17 into several component streams and thus to equalize the flow, as well as to support the porous gas permeable element 17. In other constructive forms, the grate 20 may also be absent.

The porous gas-permeable element 17 may be any suitable flame-retardant gas-permeable pressure relief element such as, for example, open-cell metal wool, metal sintered element, metal wire sintered element, where the wires may be arranged, for example, in a non-woven or felt-like manner. , or stacks of fabric or woven fabric lying on top of each other. Also, the porous gas permeable member 17 may be formed by a ceramic member, a metallized ceramic member sintered from ceramic fibers or other ceramic particles, or bonded with organic binders, or the like.

The pressure relief element 17 is provided, as seen in FIG. 2 and 3 preferably formed by a moisture-impermeable membrane 21, which preferably covers the entire surface of the element 17 on its side 22 facing the environment 14 (see FIG. 3). In this case, the membrane 21 can also extend with its edges over the part 16 and overlap it along the edge surrounding the pressure relief opening 19 . As a result, the membrane 21 seals the pressure relief opening 19, in particular against the ingress of moisture.

Preferably, the membrane 21 is formed on the body 10, also thus on the pressure relief device 15, by means of primary shaping. The element 17 and optionally the part supporting it thus form a base, in a sense a form, on which the membrane 21 is formed and thus undergoes primary shaping. In the simplest case, the membrane 21 is formed by applying the precursor composition to the pressure relief element 17 and the edge of the pressure relief hole 19, for example by spraying or by overprinting, rolling, brushing or the like. The membrane 21 can in this case, depending on the manufacturing process, be produced with a substantially constant layer thickness or with varying layer thicknesses. The material is applied to that side of the porous gas-permeable element 17 on which the lowest pressure exists in the event of a mandatory release of pressure.

The amorphous pasty or liquid precursor composition may be, for example, a partially structured or unstructured elastomer or polymer or the like, such as, for example, commercially available under the name sprayable "liquid rubber". Also, any other applied, primarily sprayable, film can be used, as long as it forms a layer that can be removed from the porous gas-permeable element 17 .

The housing 10 with the pressure relief device 15 according to the invention operates as follows.

During the preparation of the body 10, the membrane 21 is sprayed from the outside, covering the edge of the hole, onto the pressure relief hole 19 and onto the element 17 located thereon, so that the pressure relief hole 19 is closed outwards by the formed membrane 21. This prevents contamination and, if necessary, the penetration of dust or moisture into the element 17 following clogging of the pores of the element 17. For this, reference is made to FIG. 6, which shows the element 17 on its side facing the membrane 21 in section. The membrane material 21 covers the pores 23, 24, 25, 26 without penetrating deeply into them. In this case, the membrane 21 adheres to the porous element 17 so strongly that unintentional falling off of the membrane 21 from the porous gas-permeable element 17 and the housing 10 is prevented.

If the body 10, for example, through the existing slots or other openings, is filled with an explosive gas mixture, and it ignites or explodes, or one of the components 12, 13 burns, then in the internal cavity 11 there is an excess pressure relative to the environment 14, which leads to a drop pressure on the element 17 pressure relief. As a result, the membrane 21 is separated from the element 17, so that the membrane 21 can be separated from it, inflated and ruptured in the process. As a result, the now destroyed membrane 21 opens the way for the gas flowing out of the inner cavity. However, due to the length and narrowness of the pores 23-26, the element 17 prevents the flame from flashing outward.

After such an event, the membrane 21 must be replaced. In the simplest case, this occurs by re-spraying a membrane material, such as liquid rubber, onto the pressure relief hole 19 and the underlying porous gas-permeable element 17.

Numerous variations are possible in the previously described invention. The first option is shown in Fig. 7 with the multilayer membrane 21 provided. To this, in the example of FIG. 7 refer to the film 27 and the layer 21a sprayed onto it, for example consisting of liquid rubber and then cured. The film 27 adheres with low adhesion and, if necessary, with very low adhesion to the porous element 17 and covers it over part of the area or over the entire area. The sprayed layer 21a may adhere to the film 27 or only loosely adhere to it. The layer 21a may have a uniform thickness or different thicknesses. First of all, in the middle area of the film 27 it can be provided thinner or in some places, especially in the middle area, completely absent.

Such a design is particularly suitable for applications in which the membrane 21 must, at very low pressure drops, clear a path for flow through the pressure relief element 17 .

In another embodiment of this constructive form, the layer 21a may also be limited to the edge region of the film 27, so that the layer 21 creates a liquid-tight connection between the film 27 and the piece 16.

In FIG. 4 shows a structural form with a volumetrically formed pressure relief element 17, which is shown as a hemispherical dome by way of example only. However, cylindrical shapes with a flat or rounded end, polyhedral shapes, cone or frustocone shapes, and the like are also possible. The outer side of the element 17 facing the environment 14 is again provided with a spray membrane 21 which forms a release film. Otherwise, the present description of the embodiments applies according to FIG. 1-3, as well as FIG. 6 and 7.

Another variant, which is also applicable to all the indicated structural forms, is shown in Fig. 5. There, a membrane 21 is sprayed onto the porous gas-permeable element 17, which contains an additional functional element 28. This, as shown, can be a conductive strip that is applied to or embedded in the membrane 21. The conductive strip can, for example, be a conductive path formed from an electrically conductive varnish, a strip of metal foil or the like. the strip may break, and this is registered by the control circuit and notified further.

Functional elements may also be integrated into the membrane structure according to FIG. 7. For example, film 27 may carry a functional element such as electronic parts, current paths, electronic circuits, etc., which are then coated with layer 21a.

It should be noted that the membrane 21 as a whole can also be prepared in the form of a sheet of prefabricated film, which is flexible and is located against the element 17, on the device 15 pressure relief. To this end, the film may be coated on one side with an adhesive composition that promotes adhesion to the porous element 17. Alternatively, the film may be self-adhesive. The film can be made as a thermoformable film, such as a shrink film, or as a film that softens with heat and is applied to the element 17 to adhere to it.

The pressure relief device 15 according to the invention comprises a gas-permeable member 17 on which a membrane 21 is adhered, which is preferably moisture-tight. The membrane 21 can be a single or multi-layer rubber membrane, which is, for example, made by applying liquid rubber to the pressure relief element 17 and, if necessary, supporting it, framing it part 16.

List of reference designations:

10 building

11 internal cavity

12, 13 components

14 environment

15 pressure relief device

16 detail

17 porous gas permeable element / pressure relief element

18 weld

19 pressure relief port

20 lattice

21 membranes

21a a layer of rubber sprayed onto the film

22 environmental side of element 17

23-26 pores

27 film

28 functional element.

Claims (20)

1. Device (15) pressure relief for explosion-proof housing (10), having: - a porous gas-permeable element (17) having a first side, when used, facing the volume containing at least one potential source (12, 13) of initiating an explosion, and a second side, when used, facing away from the specified volume, - a membrane (21) located adjacent to the porous gas-permeable element (17), moreover, the membrane (21) is made multilayer and contains a film (27) adjacent to the porous gas-permeable element (17), which is paper, synthetic film, metal foil, composite film, composite material made of plastic and metal or fabric. 2. Pressure release device according to claim 1, characterized in that the membrane (21) is located on the porous gas-permeable element (17) with its entire surface in contact. 3. Pressure release device according to one of the preceding claims, characterized in that the membrane (21) is located on the porous gas-permeable element (17) with adhesion. 4. A pressure relief device according to one of the preceding claims, characterized in that the membrane (21) is waterproof. 5. A pressure relief device according to one of the preceding claims, characterized in that the membrane (21) is located on the porous gas-permeable element (17) in a releasably adhesive manner. 6. Pressure release device according to one of the preceding claims, characterized in that the membrane (21) also contains a layer (21a) of rubber sprayed onto the film (27) in a liquid state and then cured. 7. Pressure relief device according to one of the preceding claims, characterized in that the porous gas-permeable element (17) is a flat pressure relief element. 8. Pressure relief device according to one of paragraphs. 1-5, characterized in that the second side of the porous gas-permeable element (17) is made non-planar. 9. Pressure release device according to one of the preceding claims, characterized in that the membrane (21) extends in sections along the porous gas-permeable element (17) carrying part (16) formed by the wall of the explosion-proof housing, and is located on it with adhesion. 10. Pressure relief device according to one of the preceding claims, characterized in that the porous gas-permeable element (17) is located on the pressure relief hole (19) connecting the internal cavity (11) of the explosion-proof housing with the environment (14) and is divided into several separate holes by means of a grid (20) located on the second side of the porous gas-permeable element (17), with the membrane (21) extending over the grid (20). 11. Pressure release device according to one of the preceding claims, characterized in that the membrane (21) is produced on the porous gas-permeable element (17) by primary shaping. 12. Explosion-proof housing (10) with a pressure relief device (15) according to one of the preceding paragraphs. 13. The method of applying the membrane (21) to the porous gas-permeable element (17) for the manufacture of devices (15) pressure relief according to one of paragraphs. 1-9, in which: - the porous gas-permeable element (17) is placed on its supporting part (16) in such a way that its second side faces the environment (14), - on the film (21) adjacent to the porous gas-permeable element (17) on its second side and representing paper, synthetic film, metal foil, composite film, composite material of plastic and metal or fabric, the not yet cured membrane material is sprayed, - curing the membrane material to form the membrane (21). 14. The method according to claim 13, characterized in that the membrane material is sprayed in a continuous manner on the area of the film open to the environment (14), as well as on the area of the carrier part (16) adjacent to the porous gas-permeable element (17).

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