CZ20012105A3 - Conduit outlet seal for hazardous environments - Google Patents

Abstract

A sealing assembly for a non-circular conduit - such as an oval spare cable entry on a joint enclosure (1) - is suitable for use within a zone 1 hazardous environment, for example a sewer. The sealing assembly comprises: (i) a longitudinally compressible rubber sealing member (11) having a shape and dimensions corresponding to those of the conduit; and (ii) a first flange (17) which is electrically conductive and is shaped, dimensioned and positioned such that (a) it covers a major part of the surface of the rubber sealing member (11) and (b), in use, it is in contact with the hazardous environment. The first flange (17) can be moved relative to another member (for example using one or more bolts) to urge the sealing member (11) against the said other member to compress the rubber sealing member (11) longitudinally, causing it to be urged into sealing engagement with the conduit.

Description

Technical field

The present invention relates to a conduit seal system, such as a pipe connection outlet, wherein the seal system is intended for use in hazardous conditions, and the present invention is further directed to a method of sealing a conduit terminal intended for use in hazardous conditions.

BACKGROUND OF THE INVENTION

Hazardous environment means areas in which the atmosphere can become explosive. An explosive atmosphere is defined as a mixture of flammable substances in the form of gases, vapors or mixtures with air attaining critical atmospheric proportions of these mixtures under atmospheric conditions, as a result of which high temperatures, electrical shorts or sparks can cause an explosion. According to ”Elex V, DIN VDE 0165-1991, hazardous areas are classified into zones according to the probability of occurrence of hazardous atmospheres showing a tendency to explosion. The present invention is directed to use in the so-called "zone 1" hazardous environment. According to “Elex V, DIN VDA 0165-1991”, the explosive atmosphere zone tak is the zone in which the explosive mixture may be present under normal operation conditions. Examples of hazardous zone “zone 1” include sewers, petrochemical production and processing plants and pumping stations.

In the context of the existing sewer infrastructure, it has previously been proposed to use these walkways for routing cables, such as communication cables or power lines. As mentioned in the previous paragraph, the sewer environment is classified as “zone 1” of the hazardous environment. General articles intended for use in "zone 1" hazardous areas shall comply with the requirements of "European Standard EN 50014: 1997". Specifically, for any article intended for use in such an environment, it is critical that under normal conditions of use, maintenance and cleaning, there is no risk of ignition and subsequent ignition due to electrostatic discharges, thereby averting the risk of potential explosions.

The objects should also have a design such that the maximum surface temperature does not exceed the specified temperature, which is the ignition temperature of the gases, liquids or solids present. The value of the specified maximum temperature depends on the exact nature of the environment and this temperature is in the case of a zone Γ of a hazardous environment in the range of 85 ° C to 450 ° C. In addition, objects used in the "zone 1" hazardous area must be UV resistant, chemically inert and resistant to bending, even when the temperature is above 85 ° C.

Cables that are currently known include fiber optic or copper core cables, both of which are used for communication purposes, power distribution, and also include composite cables containing both optical fibers and copper conductors. Regardless of the cable system, it can be stated that each network system includes junction boxes at different points of the network. These junction boxes comprise means for connecting, terminating, interrupting, cable branching, etc., which are used in application of the methods and are well known to the skilled person in the art. The junction boxes are typically box-shaped boxes with cable outlets for cable entry and exit. Typically, these cable outlets are tubular and have a circular or oval cross-section, but may have a rectangular or other useful shape in said cross-section. Typically, individual cables are routed to the circular cross-sectional outlets, and a cable loop is typically introduced into the oval outlets from which a branch can be discharged without cutting the cable, so that the use of two separate outlets is unnecessary. Usually, there will be several outlets, typically from four to twelve. Generally, not all outputs will be used in the initial cable setup, and some of them will remain unoccupied to be available for cable routing if there is a need for network modification in the future. Therefore, it is imperative to ensure that these unoccupied outlets are unlocked and sealed to prevent any dirt from entering the cable junction box. If the cable junction box is to be used in a "zone 1" hazardous environment, then it is important that the means for creating an effective unblocking and sealing of any cable outlet that is not used at the outset meet the standards required of the equipment to be used in such a connection. hazardous environment. Such unlocking and sealing is easy in the case of circular guides, since the circular outlets can be sealed with threaded plugs in relation to the screwed connection to each other provided that φ φ φφφφφ φφ

The dimensions of the threaded parts meet the prescribed requirements for protection against flame or hot gas penetration into the interior between such parts. However, unlocking and sealing is often not easy when the guide is not circular, and currently best practice requires the use of an appropriately shaped closure and sealing in place with a heat-shrinking component that requires extra protection when used in certain types of hazardous environments. (for example, in the case of a sewer to protect against damage that may be caused by rodents), such a sealing component having to be cut off and discarded whenever the conduit needs to be opened, either permanently or temporarily.

DETAILED DESCRIPTION OF THE INVENTION

The present invention defines, on the one hand, a sealing assembly that is used when the conduit to be sealed is not circular, and on the other hand, defines a method for sealing a non-circular seal, always for use in the "zone 1" hazardous environment. Therefore, the present invention is suitable for use, inter alia, in sealing unused outlets from a cable junction box intended to be installed in a "zone 1" hazardous environment such as a sewer system.

If the intention is to place a cable network within an existing conduit system, it is generally assumed that the junction boxes are easily accessible. For example, if cable networks are to be distributed in an existing sewerage system, the junction boxes are usually placed immediately below manhole manhole covers for ease of access.

FR2758017A is one of many known solutions for sealing around a cable, tube, or other component that passes through a circular bore in which one elastic ring is axially compressed between two rigid rings. Such a design is clearly uneconomical for the purpose of forming a seal of a circular opening, and those skilled in the art could not consider such a design at all in connection with the construction of a seal through which no cable passes.

A first feature of the present invention provides a conduit seal assembly comprising (i) a longitudinally compressible, rubber sealing member; and (ii) a first flange that is electrically conductive, and a first flange that is electrically conductive.

It covers a greater part of the surface of the rubber sealing member and is in contact with a hazardous environment under conditions of use, the first flange being able to move relative to the other member so as to push the sealing member against said other member to longitudinally compress the rubber member, wherein the rubber sealing member is pressed into a sealing connection with the conduit, wherein the sealing assembly is intended for use in hazardous zone 1, the conduit outlet is not circular in cross section, and the rubber sealing member and first flange have corresponding non-circular shape and dimensions.

A second feature of the present invention provides a method of sealing a lead conduit comprising the steps of (i) placing a longitudinally compressible rubber seal of a component in contact with a lead and positioning of a first flange that is electrically conductive covering a major portion of the rubber seal member surface; the conditions of use are in contact with the hazardous environment; and (ii) displacing the first flange relative to the other member so as to push the sealing member against said other member to longitudinally compress the rubber member, thereby pressing the rubber member into a sealing connection with the conduit; and (iii) installing the conduit and sealing system used in the hazardous environment, wherein the seal assembly is intended for use in hazardous zone 1, the conduit outlet is not circular in cross section and the rubber sealing member and the first flange have corresponding non-circular shape and dimensions.

As used herein, longitudinally compressible means that the sealing member is compressible in a direction that is substantially parallel to the axis of the conduit.

All advantageous features of the sealing system of the present invention also apply to the method of the present invention.

The present invention is primarily intended to provide padding closures, which are closures through which no cable pipe or other component passes.

Advantageously, said further component is a second flange which is positioned such that the rubber sealing member is located within the conduit outlet between the first flange and the second flange, in which case the shape and dimensions of the rubber sealing member will normally substantially converge the internal shape and dimensions of the conduit outlet. Both flanges may be in direct contact with the sealing member and other intermediate members may be used. One of the flanges or both the first and second flanges may be generally flat.

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In this embodiment, in which the sealing member is disposed in the conduit outlet, the transverse dimension of the sealing component is increased as a result of the longitudinal compression of the sealing component, and thereby pressurized into sealing contact with the inner surface of the conduit outlet.

In a further embodiment, said further component is an end face of a conduit, and in this alternative design, the shape and dimensions of the rubber sealing member are substantially similar to the inner shape and dimensions of the conduit.

In accordance with both features of the present invention, the sealing member comprises a compressible rubber, which is preferably an EPDM material. Although this material is well usable for the purpose of the desired sealing function, exposing the surfaces of polymer or rubber materials to zone 1 hazardous areas is unacceptable since these materials tend to accumulate electrostatic charges and, as a result, there is a risk of spark leakage and possible explosion. In some types of hazardous environments, such materials may also be susceptible to deterioration when exposed to liquids occurring in the environment (for example, mud gases or oil vapors). In accordance with the present invention, this problem is minimized by providing a first, generally flat flange, which is electrically conductive and positioned to be exposed to the surrounding hazardous environment to a greater extent than the rubber sealing member. This certainty is achieved when the first flange covers a major portion of the surface of the rubber sealing member. In a preferred embodiment, one larger flange surface is in contact with the rubber sealing member and the other larger flange surface is in contact with the hazardous environment.

The first flange is preferably electrically conductive to such an electrical resistance that does not exceed 1 Gohm at (23 ± 2) ° C and (50 ± 5)% relative humidity based on measurements according to clause 23.4.7.8 of European Standard EN It is preferred that the first flange comprises metal. A particularly preferred metal is steel, especially stainless steel. Other metals useful in this regard include aluminum, cast iron, galvanized steel, bronze and brass. A polymer material with adequate electrical conductivity can be used as a metal substitute.

The electrically conductive first flange is adapted to separate the rubber sealing member from the hazardous environment. In this sense, the first flange covers the main part of the rubber sealing member. Thus, the first flange preferably covers at least 90% and in particular at least 90%.

- preferably 95% of the surface of the rubber sealing member. Preferably, the first flange covers a sufficient portion of the surface of the sealing member such that each surface length of the sealing member which is exposed to a hazardous environment under conditions of use and that varies radially with respect to the conduit outlet is less than 1 cm. The term radially in relation to the conduit terminal indicates a direction from the axis of the conduit terminal to the outer surface of the conduit terminal. This is true irrespective of the cross-sectional shape of the conduit, so this shape may be, for example, oval, rectangular or some other usable form. These technical measures make sense in that it is practically impossible to accumulate electrostatic charges on the insulating surface of the rubber sealing component. It is preferred that the exposed portion of the surface area of the rubber sealing member is not sufficient to accumulate an amount of energy that could create a spark. Even if such precautions still do not provide complete safety, the rubber seal itself may in some cases be filled with carbon or other usable material to impart electrical conductivity to the rubber seal.

In those embodiments in which the first flange extends transversely to the top of the conduit outlet to seal the conduit, the first flange could additionally be introduced downwardly along the outer surface of the end cap seal.

In preferred embodiments and methods of the invention, the conduit may also comprise metal. Metals and conductive polymeric materials that have been mentioned in connection with preferred materials for the first flange are also useful materials for lead-out purposes. In one preferred embodiment, the system also comprises a junction box in the form of a box, preferably a metal box, wherein said conduit terminal forms a cable outlet from the junction box. The housing preferably comprises a plurality of cable outlets. These outlets may have different cross-sectional shapes, especially circular, oval or rectangular, but the present invention is directed only to sealing those outlets that do not have a circular cross-sectional shape.

The sealing of the conduit outlets is preferably performed outside the hazardous environment and then the sealed conduit is installed in the hazardous environment. In connection with a sewer system, for example, a manifold (for example, a junction box with a certain number of sealed lines and other lines containing cables) is sealed above ground level and then introduced into the sewer through an inlet sewer shaft to create convenient a sag that will allow the cable to be pulled out when adjustments or maintenance are required.

• · · · ·

In accordance with standards required for installation of distribution lines in hazardous (grounded). This technical measure ensures that there will be no difference in electrical potential between the flange and the line, which must also be secured by connecting to the zero electrical potential, and this is typically done through the box to which the line is connected. This measure again minimizes the possibility of the spark being skipped and the subsequent ignition and explosion possible.

It is preferred that the sealing member has one or more holes and that the second flange also comprises holes following the corresponding number of screws (or no further holes). In a preferred embodiment of the present invention, the first flange itself forms a bolt head (or more than one bolt) that extends through the bore (s) in the sealing member and the second flange, the assembly additionally comprising one or more nut and shank bolt fasteners, so that due to the tightening of these nuts, the first and second flanges are pulled together. It is also possible to use mechanical fastening means other than the nut and bolt means, provided that they pass through the holes in the sealing member and the second flange, and such technical solutions are apparent to those skilled in the art.

In preferred embodiments of the present invention, the overall sealing assembly comprises two or more than two layered, compressible sealing members that are separated from one another by one or more rigid spacers. These inserts can be made of polymeric material or metal or other useful material because they are not exposed to the hazardous environment. Alternatively, a single sealing member may be used. The sealing components can be made by any applicable method, such as molding or molding.

The sealing assembly also preferably includes means to prevent excessive compression of the sealing components. In accordance with the preferred practice of mechanical engineering, preferably means for limiting the compression range are used which do not allow the sealing member (s) to be compressed above the respective Shore compression limit. These means for limiting the compression range are generally rigid rings that are disposed between the first and second flanges. Prior to compression of the sealing member, such a ring is only located on a portion of the distance between the first and second flanges. As a result of getting closer to each other, these flanges «· · · ··· * · * • φφφ · · φφφ φ · · · φ · · φ φφφφφφφφ φφφφφφφφ

They are in abutment contact with the opposite ends of the ring to define the extent of compression, and thus the further flanging of the two flanges is generally impossible. In this way, the sealing components cannot be excessively compressed. Where the assembly comprises two or more aperture sealing members and a corresponding number of apertures with an aperture positioned between said sealing members, such means for limiting the extent of compression are preferably in the form of a rigid sleeve that is shaped to fit into the respective apertures.

Overview of the drawings

Reference will now be made to exemplary embodiments of the present invention with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of a cable splice box from which a plurality of tubular cable outlets with a circular cross-section and one oval cable outlet protrudes;

Fig. 2 is a longitudinal cross-sectional view of the oval outlet of the box illustrated in Fig. 1, with particular reference to the embodiment of the sealing assembly of the present invention; and Fig. 3 is a plan view of the sealing assembly shown in Fig. 2.

DETAILED DESCRIPTION OF THE INVENTION

Giant. 1 illustrates a stainless steel junction box 1, which may include, for example, a fiber optic binder box and / or electronic printed circuit boards (not shown). The metal box 1 has a metal body part 3 and a lid 5 that can be detached to provide access to the interior of the box when making connections and the like. Six cable outlets 7, 8 having a generally circular cross-sectional shape and one cable outlet 9 having a generally oval cross-sectional shape protrude from the cover 5 of the cable junction box. The oval outlet 9 is intended to be closed by a sealing assembly according to the present invention. will be described in detail below with reference to the remaining illustrations. Some of the outlets 7 having a circular cross-section are open for cable entry, and others can be • • · · · * · · · φ φ φ φ

ΦΦφ φφ «φ« * φφ «Φφ

-9 sealed to plug in any known manner, such as screwing plugs or threaded caps. Each outlet 7, 8,9 typically protrudes from box 1 to a distance of approximately 30 cm.

Giant. 2 and 3 show a sealing assembly according to the present invention which is placed in a cable outlet 9 having an oval cross-sectional shape as shown in FIG. 1. The sealing system comprises three longitudinally compressible sealing members 11 which are made of EPDM and which they separate two generally rigid, polymer spacer inserts

13. Each of the sealing members 11 and the polymer spacer 13 has substantially the same oval shape and size as the shape and size of the internal cross section of the conduit 9, but the clearances of the rigid spacer may be slightly greater than the clearance of the rubber sealing member (ie, how they were made). Openings are formed in each sealing member 11 and the spacer 13, the axial continuity of which is identical to one another. Screws 19 of the same material are welded to the first stainless steel flange. Stainless steel. When assembled, the first stainless steel flange 17 contacts the surface of the EPDM outer sealing member II and almost covers the surface of said external sealing member 11 of the system, so that the first flange 17 is exposed to a hazardous environment. Screw shafts 19 extend through openings in the sealing components 13. The washer 31 is positioned adjacent to the sealing member 11 that is furthest from the head 15 of the bolt 17. This washer 31 forms the second flange of the present invention and is generally flat. On both screws is screwed nut 23, which is in contact with the washer 31, and due to the screwing of the nut on the shank of the screw, the first flange 17 and the second flange 31 (washer) are pulled together and then the sealing components expand radially in contact with The rigid sleeve 24 for defining the extent of compression, which is made of Nylon 66, is located only over a portion of the shank length of each screw 19 between the flange 17 and the washer 31 (the second flange). The lengths of the sleeves 24 are selected such that overpressure of the sealing members 11 beyond their Shore compression limit is prevented, and the flanges 17 and 31 are supported at respective opposite ends of the sleeves 24 to define the compression range before said limit is reached. value of compression. In Fig. 2, the sealing members 11 are shown in their compressed state. A pin 25 is attached to one of the bolts 19 by means of the other nut 27, which connects the seal assembly to zero electrical potential. This earthing pin 25 ensures that there is no difference in electrical potential between the screw 17 and the outlet 9 and the rest of the box. Any difference in electrical potential would indeed be dangerous if the sealing system was installed in Zone 1 of the hazardous environment as it could cause a spark. The star pad 29 is also incorporated to ensure good electrical contact and good vibration resistance.

From the construction shown in FIG. 3, it can be seen that the metal flange 17 of the screw 15 covers most of the surface of the adjacent EPDM sealing member 11. Therefore, the possibility of accumulation of electric charge on the surface of the insulating sealing member 11 and thus the possibility of subsequent ignition and explosion is virtually impossible.

Claims (19)

PATENT CLAIMS A lead outlet seal assembly comprising (i) longitudinally compressible. a rubber sealing member; and (ii) the first flange, which is electrically conductive, covers most of the surface of the rubber sealing member and is in contact with a hazardous environment under conditions of use, the first flange being movable relative to the other member to push the sealing member against said further components for longitudinally compressing the rubber component, thereby pressing the rubber sealing component into a sealing connection with the conduit, characterized in that the sealing assembly is intended for use in hazardous zone 1, the conduit outlet does not have a circular cross section the shape and the rubber sealing member and the first flange have corresponding non-circular shape and dimensions. 2. The sealing assembly of claim 1 wherein said second component is a second flange positioned so that the rubber sealing member is located between the first flange and the second flange. Sealing assembly according to claim 1 or 2, characterized in that the first flange is generally flat. Sealing assembly according to claim 2 or 3, depending on claim 2, characterized in that the second flange is generally flat. Sealing assembly according to any one of claims 1 to 4, characterized in that the sealing member is positioned within the conduit outlet and, due to the longitudinal compression of the sealing member, increases its transverse dimension, thereby pressing said sealing member into sealing contact with the inner surface. outlet for sealing. 6. The seal assembly of claim 1, wherein said additional component forms an end face of a conduit. · Φ φ · · · · · · · · · · · · · · · · · · · · · · Sealing assembly according to any one of the preceding claims, characterized in that the first flange comprises a metal, preferably stainless steel. Sealing assembly according to any one of claims 1 to 7, characterized in that the conduit outlet comprises metal, preferably stainless steel. Sealing assembly according to any one of the preceding claims 1 to 8, wherein the first flange covers at least 80% of the surface area of the rubber sealing member after the sealing member has been compressed into sealing contact with the conduit outlet. Sealing assembly according to any one of the preceding claims 1 to 9, characterized in that the first flange covers a portion of the surface of the seal sufficient to cause the surface length of the sealing member exposed to hazardous environments to be less than 1 cm in use. if measured radially in relation to the lead. A sealing assembly according to claim 2, wherein each sealing member and the second flange have at least one bore that is guided in axial alignment and that the first flange forms the head of the at least one screw extending through the bores in the sealing member and in the second flange. wherein the system additionally comprises a nut for each screw that can be tightened, as a result of which the first flange and the second flange attract each other. Sealing assembly according to any one of the preceding claims 1 to 11, characterized in that it comprises two or more compressible sealing members which are superimposed and separated from one another by generally rigid spacer inserts. Sealing assembly according to any one of the preceding claims 1 to 12, further comprising a compression range limiting component that defines the compression range of the sealing member (s). * * * * · · · · · · · * * * * * * * * * * * * * 14. The seal assembly of claim 13, wherein said further component is a second flange and wherein the compression range limiting component is disposed between the first flange and the second flange and occupies only a portion of the distance between the first flange and the second flange. A sealing assembly according to any one of the preceding claims 1-4, wherein said conduit outlet is a cable outlet from a cable splice box, the outlet being for temporary sealed blanking. A sealing assembly according to any one of the preceding claims 1 to 15, which seals the conduit outlet by compressing the sealing member and is installed in the hazardous area zone 1. 17. The sealing assembly of claim 16, wherein said hazardous zone 1 is a sewage system. A method of sealing a lead outlet comprising the steps of (i) placing a longitudinally compressible, rubber sealing member in contact with a lead and locating a first flange that is electrically conductive, covers a major portion of the surface of the rubber seal member and is in use under conditions of use; contact with hazardous environment; (ii) displacing the first flange relative to the other member to urge the sealing member against said other member to longitudinally compress the rubber member, thereby pressing the rubber seal member into a sealing connection with said conduit outlet; and (iii) installing the conduit and sealing system thus used in a hazardous environment, characterized in that the sealing assembly is intended for use in hazardous area zone 1, the conduit outlet is not circular in cross section and the rubber sealing component and the first flange have corresponding non-circular shape and dimensions. »· ··· * · - ΜΙ 9. Sealing assembly as described overall with reference to the attached drawings. A method of sealing a lead for a conduit which is intended to be installed in a hazardous area zone 1 as generally described with reference to the accompanying drawings.