DK153186B

DK153186B - FIRE PROTECTED FIBER CABLE

Info

Publication number: DK153186B
Application number: DK188484A
Authority: DK
Inventors: Magne Spillum; Leif Egil Gjoennes
Original assignee: Norsk Fiberoptikk As
Priority date: 1983-04-13
Filing date: 1984-04-11
Publication date: 1988-06-20
Also published as: DK188484A; DK188484D0; GB2138168A; NO153549C; SE8402021D0; GB2138168B; NO153549B; SE454302B; DK153186C; NO831307L; SE8402021L

Description

Den foreliggende opfindelse angår et brandsikkert fiberkabel omfattende en signalbærende optisk fiber, som er omsluttet af en beskyttende kappe, fortrinsvis et rør ("loose tube") af organisk materiale.The present invention relates to a fireproof fiber cable comprising a signal-carrying optical fiber enclosed by a protective jacket, preferably an organic material "loose tube".

Det er sædvanligt, at optiske fibre består af højrent kvartsglas, dvs. siliciumdioxid, som til opnåelse af nødvendig brydningsindeksvariation er dopet med germanium, phosfor, bor eller fluor. Selve den optiske fiber kan således omfatte en dopet kerne på f.eks. 50 mikrometer, med et omgivende glaslag med en diameter på f.eks. 125 mikrometer.It is usual for optical fibers to consist of high-purity quartz glass, ie. silica which is doped with germanium, phosphorus, boron or fluorine to obtain the required refractive index variation. Thus, the optical fiber itself may comprise a doped core of e.g. 50 microns, with a surrounding glass layer having a diameter of e.g. 125 microns.

Fiberoverfladen skal straks beskyttes mod fugtighed og mekanisk beskadigelse med et lag akrylat, acetat, silikongummi eller lignende. Dette kaldes fiberens primærbelægning. Fibrene beskyttes ofte yderligere, før de kan indgå i en kabel konstruktion, og denne beskyttelse omfatter som regel to kategorier, nemlig en løs eller tæt beklædning.The fiber surface must be immediately protected from moisture and mechanical damage with a layer of acrylate, acetate, silicone rubber or the like. This is called the primary coating of the fiber. The fibers are often further protected before they can form part of a cable construction, and this protection usually comprises two categories, namely loose or dense cladding.

Ved løs beklædning bliver fiberen omgivet af et hult rør, fortrinsvis et rør af organisk materiale med en inderdiameter på f.eks.In loose casing, the fiber is surrounded by a hollow tube, preferably a tube of organic material having an inner diameter of e.g.

1 mm og en vægtykkelse på 0,2 - 0,3 mm. Fiberen ligger løst inde i dette rør ("loose tube"), som iøvrigt ofte kan være fedtfyldt for yderligere fugtighedsbeskyttelse.1 mm and a wall thickness of 0.2 - 0.3 mm. The fiber lies loosely inside this tube ("loose tube"), which can also often be greasy for additional moisture protection.

Kablet kan nu konstrueres således, at de mekaniske påvirkninger ikke i særlig grad overføres til fiberen.The cable can now be designed so that the mechanical stresses are not particularly transmitted to the fiber.

Ved tæt beklædning er fiberen omgivet af en relativt tyk (typisk 100 mikrometer) primærbelægning af f.eks. blødt silikongummi, og i direkte kontakt med dette silikongummilag extruderes der et lag af stivere plast. Den totale diameter af den beskyttede fiber med tæt beklædning kan være ca. 0,9 -1,0 mm.In dense cladding, the fiber is surrounded by a relatively thick (typically 100 microns) primary coating of e.g. a soft silicone rubber, and in direct contact with this silicone rubber layer, a layer of stiffer plastic is extruded. The total diameter of the dense sheathed fiber can be approx. 0.9 -1.0 mm.

De beskyttede fibre kan derefter indgå i en større kabel konstruktion.The protected fibers can then form part of a larger cable construction.

I forbindelse med udviklingen af fiberkabler er der lagt speciel vægt pi at forøge overføringskapaciteten samt at gøre kablet så modstandsdygtigt mod mekanisk beskadigelse som muligt. Denne udvikling er imidlertid sket i forbindelse med installationsmilieuer, som ikke har været klassificeret som specielt brandfarlige.In connection with the development of fiber cables, special emphasis has been placed on increasing the transmission capacity and making the cable as resistant to mechanical damage as possible. However, this development has occurred in connection with installation environments that have not been classified as particularly flammable.

Til grund for den foreliggende opfindelse ligger den opgave ikke kun at give anvisning på et fiberkabel, som vil have god mekanisk beskyttelse under normale driftsforhold, men som også vil kunne bibeholde sine driftsegenskaber i tilfælde af brand.The object of the present invention is not only to provide a fiber cable which will have good mechanical protection under normal operating conditions, but which will also be able to retain its operating characteristics in the event of fire.

Sædvanlige fiberkabler af den ovenfor angivne art, f.eks. af den type, som er fremstillet efter løsbeklædnings- eller "loose tube"-princippet for at undgå mikrobøjninger af fiberen og give en god mekanisk beskyttelse, vil ikke kunne give tilstrækkelig beskyttelse under en brand, idét det organiske materiale, som omslutter fiberkablet, vil brænde op, således at den mekaniske beskyttelse af fiberen vil forsvinde.Usual fiber cables of the above type, e.g. of the type made according to the principle of loose lining or "loose tube" principle to avoid micro-bends of the fiber and to provide good mechanical protection, will not be able to provide adequate protection during a fire, as the organic material enclosing the fiber cable will burn up so that the mechanical protection of the fiber will disappear.

Et hovedformål med den foreliggende opfindelse er således at tilvejebringe et kabel, som giver en rørlignende beskyttelse af den optiske fiber selv under en brand, dvs. at give anvisning på et beskyttelsesrør, som opstår under selve branden.Thus, a principal object of the present invention is to provide a cable which provides a tube-like protection of the optical fiber even during a fire, i.e. to give instructions on a protective tube that arises during the fire itself.

Dette formål opnås ifølge oprindelsen ved den kombination, at den beskyttende kappe er belagt med mikabånd, fortrinsvis mika-bånd på en glasbærer, og at den beskyttende kappe mellem sig og den optiske fiber rummer et materiale, som forhindrer oxidering af den optiske fiber og giver få reststoffer ved en brand, f.eks. modificeret silikonfedt, hvilket silikonfedt ved brand danner fint kvartspulver, der bibeholder en støttefunktion af fiberen, idet mikabåndet danner et sintret rør, som erstatter kappen og holder kvartspulveret på plads rundt om fiberen.This object is achieved according to the origin by the combination that the protective sheath is coated with micro-strips, preferably mica bands on a glass carrier, and that the protective sheath between itself and the optical fiber contains a material which prevents oxidation of the optical fiber and gives get residuals in case of fire, e.g. modified silicone grease, which, on fire, forms fine quartz powder which maintains a supporting function of the fiber, the micband forming a sintered tube which replaces the casing and holding the quartz powder in place around the fiber.

Hensigtsmæssigt kan den beskyttende kappe eller det beskyttende rør være belagt med mikabånd, fortrinsvis mikabånd på en glasbærer og fortrinsvis i form af en båndbevikling.Conveniently, the protective sheath or protective tube may be coated with microbands, preferably microbands on a glass carrier, and preferably in the form of a ribbon winding.

Under en brand vil specielt mikabåndet blive underkastet en sintringsproces og danne et nyt rør, som beskytter fiberen. Man vil da kunne undgå, at fiberen på grund af mekanisk og termisk påvirkning vil indtage mi krobøjninger og derved hindre, at lys stråler ud. Sådanne mikrobøjninger er kritiske for den forbindelse, som skal opretholdes gennem en optiske fiber, og det er derfor vigtigt, at den mekaniske beskyttelse bibeholdes.In particular, during a fire, the micro-band will be subjected to a sintering process to form a new tube which protects the fiber. It would then be possible to avoid the fiber, due to mechanical and thermal influences, taking in the bending curves, thereby preventing light from radiating. Such micro-bends are critical to the connection to be maintained through an optical fiber, and it is therefore important that mechanical protection be maintained.

Et silikonfedt vil ved brand danne et fint kvartspulver, som bibeholder en støttefunktion af fiberen, og vil foruden at bidrage til, at fiberkablet bibeholder sin løse beklædning, også bidrage til, at fiberen under brand får tilført mindst muligt oxygen for derved at hindre oxidering af den optiske fiber. En bar optisk fiber vil under brand oxidere på én gang, og fiberens mekaniske egenskaber bliver ødelagt. Fiberens brudstyrke kan da reduceres til mindre end 10% af den oprindelige.In case of fire, a silicone grease will form a fine quartz powder, which retains a supporting function of the fiber, and will, in addition to helping the fiber cable retain its loose lining, also contribute to the fiber under fire getting as little oxygen as possible to prevent oxidation of the the optical fiber. A bare optical fiber will oxidize under fire at one time and the mechanical properties of the fiber will be destroyed. The breaking strength of the fiber can then be reduced to less than 10% of the original.

Når man bruger materialer som angivet ovenfor, kan man ved det brandsikre fiberkabel også anvende fibre med forskellige primærbelægninger, som findes på markedet, f.eks. silikonbelægning, akrylat eller en eller anden form for lak, eventuelt aluminiumbelægning.When using materials as indicated above, the fire-resistant fiber cable can also use fibers with various primary coatings available on the market, e.g. silicone coating, acrylate or some form of lacquer, optionally aluminum coating.

Det vil forstås, at det organiske rør ikke nødvendigvis skal fyldes med silikonfedt, idet et hvilket som helst andet materiale, som opfylder egenskaberne med hensyn til volumenforøgelse, gasudvikling og brændbarhed under en brand samt under normal brug har lille udvidelseskoefficient og lille viskositetsændring med temperaturen, kan benyttes.It will be understood that the organic tube does not necessarily have to be filled with silicone grease, as any other material which satisfies the characteristics of volume increase, gas evolution and flammability during a fire as well as under normal use has a small coefficient of expansion and a small change in viscosity with temperature. can be used.

For yderligere at sikre kabel konstruktionen mod brand kan der uden på beskyttelsesrøret med den brandhæmmende belægning og glasbånd være omsluttet en fyldkappe med gode brandhæmmende egenskaber.To further protect the cable construction against fire, a filler jacket with good fire-retardant properties can be enclosed on the outside of the protective tube with the fire-retardant coating and glass band.

Hensigtsmæssigt kan der uden på en sådan fyldkappe være anbragt et andet glasbånd eventuelt med en stålarmering over båndet. En sådan yderligere foranstaltning vil yderligere styrke kablets mekaniske beskaffenhed under og efter en brand.Conveniently, on the outside of such a filler cap, a second glass band may be provided, optionally with a steel reinforcement over the band. Such an additional measure would further strengthen the mechanical nature of the cable during and after a fire.

Endelig kan kablet have en yderkappe af et materiale, som danner en beskyttelsesaske under brand, f.eks. ethylenvinylacetat eller ethylenetylacrylat fyldt med aluminiumhydroxid, kridt osv.Finally, the cable may have an outer sheath of a material which forms a protective case under fire, e.g. ethylene vinyl acetate or ethylene ethyl acrylate filled with aluminum hydroxide, chalk, etc.

Kabler i henhold til den foreliggende opfindelse har været afprøvet i et brandkammer, hvor de blev udsat for brand ved 930°C i 3 timer. Det viste sig, at kablerne var funktionsdygtige under hele brandforsøget, dvs. overførte nødvendig lysenergi, som blev udsendt ved den ene kabelende for tilfredsstillende påvirkning af modtagerelementer anbragt ved den anden ende af kablet.Cables of the present invention have been tested in a fire chamber where they were exposed to fire at 930 ° C for 3 hours. It turned out that the cables were functional throughout the fire trial, ie. transmitted necessary light energy which was emitted at one end of the cable for satisfactory operation of receiver elements located at the other end of the cable.

Den foreliggende kabel konstruktion udviser en forholdsvis lav termisk ledningsevne under normale anvendelsesforhold, hvilket er gunstigt for beskyttelsen af den optiske fiber, således at denne bliver mindst muligt påvirket af temperaturændringer. Den forholdsvis lave termiske ledningsevne er heller ikke ugunstig, når det drejer sig om bortførsel af udviklet energi i den optiske fiber, idet denne energiudvikling må betegnes som så at sige ubetydelig.The present cable construction exhibits a relatively low thermal conductivity under normal conditions of use, which is favorable for the protection of the optical fiber, so that it is least affected by temperature changes. The relatively low thermal conductivity is also not unfavorable when it comes to the dissipation of developed energy in the optical fiber, since this energy development must be considered as insignificant.

Kabel konstruktionen giver få eller ingen korroderende virkninger på omgivelserne under brand og vil ved sin materialesammensæt ning tilfredsstille strenge brandtekniske, mekaniske og operationsmæssige betingelser både før, under og efter en brand.The cable construction provides little or no corrosive effects on the environment during fire and will, by its composition of materials, satisfy stringent fire technical, mechanical and operational conditions both before, during and after a fire.

Opfindelsen skal herefter forklares nærmere under henvisning til tegningen, hvor fig. 1 viser et snit i en første udførelsesform for et brandsikkert fiberkabel ifølge den foreliggende opfindelse og fig. 2 et snit i en anden udførelsesform for et brandsikkert fiberkabel ifølge opfindelsen.The invention will now be explained in more detail with reference to the drawing, in which fig. 1 is a sectional view of a first embodiment of a fireproof fiber cable according to the present invention; and FIG. 2 is a sectional view of another embodiment of a fire-resistant fiber cable according to the invention.

I fig. 1 betegner 1 en eventuel indre kerne af stål eller fiberforstærket plast med høj mekanisk styrke og lav temperaturudvidelseskoefficient. En sådan kerne kan med fordel benyttes, når kablet skal indeholde mere end én fiber.In FIG. 1, 1 denotes an optional inner core of steel or fiber reinforced plastic with high mechanical strength and low temperature expansion coefficient. Such a core can advantageously be used when the cable must contain more than one fiber.

Rundt om kernen 1 er der i det viste udførelseseksempel anbragt fire optiske fibre 2a-2d, som kan være belagt med et lag af akrylat, acetat eller silikongummi, idet dette lag beskytter mod fugtighed og mekaniske beskadigelser af selve den optiske fiber.Around the core 1, in the embodiment shown, four optical fibers 2a-2d are arranged which may be coated with a layer of acrylate, acetate or silicone rubber, this layer protecting against moisture and mechanical damage to the optical fiber itself.

Rundt om hver af de optiske fibre 2a-2d er der anbragt et rør 4 af organisk materiale, f.eks. akryl, og i hulrummet mellem røret 4 og de enkelte fibre 2a-2c er der fyldt silikonfedt 3, idet kombinationen akrylrør 4 og silikonfedt giver en såkaldt løs beklædning eller "loose tube"-montering af de optiske fibre 2a-2d.Around each of the optical fibers 2a-2d a tube 4 of organic material, e.g. acrylic, and in the cavity between the tube 4 and the individual fibers 2a-2c silicone grease 3 is filled, the combination of acrylic tube 4 and silicone grease giving a so-called loose coating or "loose tube" mounting of the optical fibers 2a-2d.

Rundt om røret 4 af organisk materiale er der viklet et lag af mikabånd, idet mikamateriaiet hensigtsmæssigt kan være anbragt på en glasbærer.Around the tube 4 of organic material, a layer of micro-tape is wound, the micro-material being suitably arranged on a glass carrier.

Under brand vil det materiale, som røret 4 er belagt med, f.eks. mikabånd, undergå en sintringsproces, således at der dannes et nyt rør til erstatning for selve det organiske rør 4, hvilket bidrager til, at den mekaniske beskyttelse af selve de optiske fibre 2a-2d opretholdes under og efter en brand. Samtidig vil fyldmassen 3, f.eks. silikonfedtet i mellemrummet mellem røret 4 og de enkelte optiske fibre 2a-2d, være af en sådan beskaffenhed, at der under en brand bliver produceret færrest mulige reststoffer for derved at undgå oxidering, gasudvikling, tilsodning og trykforøgelser mellem røret 4 og fibrene 2a-2d. Foruden at reducere faren for trykforøgelse under brand vil silikonfedtet 4 også have en lille udvidelseskoefficient og lille viskositetsændring med temperaturen. Disse forhold bidrager også til, at vandringen af fibrene 2a-2d bliver mindst mulig både under normale driftsforhold og under brandforhold, hvilket indebærer, at fibrene bliver påvirket mindst muligt mekanisk og derved undgår mi krobøjninger, som medfører, at det lys, som føres gennem de optiske fibre, vil stråle ud og ikke nå frem til bestemmelsesstedet for opretholdelse af forbindelsen mellem de to kabelender. Sandsynligheden for brud i fiberen reduceres tilsvarende.Under fire, the material with which the tube 4 is coated, e.g. microbands, undergo a sintering process so that a new tube is formed to replace the organic tube 4 itself, which helps maintain the mechanical protection of the optical fibers 2a-2d itself during and after a fire. At the same time, the filler 3, e.g. the silicone grease in the space between the tube 4 and the individual optical fibers 2a-2d must be of such a nature that as few fires are produced during a fire as to avoid oxidation, gas evolution, seeding and pressure increases between the tube 4 and the fibers 2a-2d . In addition to reducing the danger of pressure increase under fire, the silicone grease 4 will also have a small expansion coefficient and small viscosity change with temperature. These conditions also contribute to minimizing the migration of the fibers 2a-2d, both under normal operating conditions and under fire conditions, which means that the fibers are mechanically affected as little as possible, thereby avoiding miter bends, which results in the light passing through the optical fibers will radiate and not reach the destination of maintaining the connection between the two cable ends. The probability of breakage in the fiber is reduced accordingly.

Rundt om et rør eller en samling af organiske rør med den brandhæmmende belægning 5 er der anbragt et lag af glasbind 6, idet båndet tjener til at støtte konstruktionen bide før og efter en brand, samtidig med at det giver en ekstra flammebeskyttelse af mikabåndet 5.Around a pipe or assembly of organic pipes with the fire-retardant coating 5, a layer of glass band 6 is provided, the band serving to support the construction of bite before and after a fire, while providing additional flame protection of the micro band 5.

Uden på glasbindet 6 er der anbragt en fyld kappe 7 med gode brandhæmmende egenskaber.Outside of the glass binder 6, a filling jacket 7 is provided with good fire-retardant properties.

Uden på fyldkappen 7 er der ved udførelsesformen vist i fig. 1 anbragt et yderligere glasbånd 8, eventuelt armeret med stål over båndet. En sådan sammenstilling tjener til at holde fyldkappen 7 pi plads, når denne under brandforhold går over til at blive en keramisk beskyttel ses kappe.Outside of the filler cap 7, in the embodiment shown in FIG. 1, a further glass band 8 is arranged, optionally reinforced with steel over the band. Such an assembly serves to hold the filler cap 7 in place when under fire conditions it becomes a ceramic protective cap.

Uden på glasbåndet 8 er der anbragt en yderkappe med gode brandhæmmende egenskaber, idet materialet er af en sådan beskaffenhed, at det giver en beskyttelsesaske under brand, eksempelvis kan yderkappen have en basiskomponent, som omfatter ethylenvinyl-acetat eller ethylenetylacrylat, som er fyldt med aluminiumhydroxid, kridt m.m. for at kunne danne en formbestandig aske ved brand.Outside of the glass band 8, an outer casing is provided with good fire-retardant properties, the material being of such a nature that it provides a protective box under fire, for example, the outer casing may have a basic component comprising ethylene vinyl acetate or ethylene ethyl acrylate filled with aluminum hydroxide. , chalk, etc. to form a fire resistant ash.

I fig. 2 er der vist et snit gennem en anden udførelsesform for en kabel konstruktion ifølge den foreliggende opfindelse, idet de grundkomponenter, som indgår i kabel konstruktionen, her er de samme som i forbindelse med udførelsesformen vist i fig. 1, men hvor antallet af fiberkerner er forskelligt fra den tidligere omtalte udførelsesform. Således er der i fig. 2 vist et centralt element 1 af stål eller fiberforstærket plast, eventuelt glas med høj mekanisk styrke og lav temperaturudvidelseskoefficient, samtidig med at der rundt om kernen 1 er anbragt seks optiske fibre 2a-2f, som er anbragt i en krans omkring kernen 1.In FIG. 2 shows a section through another embodiment of a cable construction according to the present invention, the basic components included in the cable structure being the same as in connection with the embodiment shown in FIG. 1, but where the number of fiber cores is different from the previously mentioned embodiment. Thus, in FIG. 2 shows a central element 1 made of steel or fiber-reinforced plastic, optionally high mechanical strength glass and low temperature coefficient of expansion, while six optical fibers 2a-2f are arranged around a core around a core 1.

løvrigt er opbygningen af kabelvarianten i fig. 2 udført tilsvarende den, der er omtalt i forbindelse med fig. 1.The structure of the cable variant in FIG. 2, similar to that discussed in connection with FIG. First

Forsøg har vist, at en kabel konstruktion ifølge opfindelsen kan modstå en brand ved 930°C i 3 timer uden at miste sin funktionsdygtighed, dvs. uden at få reduceret det signalniveau for lystransmission, som er nødvendigt for pålidelig kommunikation mellem de to ender af kablet. Kabel konstruktionen ifølge opfindelsen skulle således kunne tilfredsstille kravene om at kunne være funktionsdygtig i en halv time ved en carbonhydridbrand, hvor temperaturer på over 900°C ofte kan forekomme.Tests have shown that a cable construction according to the invention can withstand a fire at 930 ° C for 3 hours without losing its functionality, ie. without reducing the signal level of light transmission needed for reliable communication between the two ends of the cable. The cable construction according to the invention should thus be able to satisfy the requirements of being able to operate for half an hour in a hydrocarbon fire, where temperatures above 900 ° C can often occur.

Claims

A fire-resistant fiber cable comprising a signal-carrying optical fiber (2a-2d) enclosed by a protective sheath (4), preferably an organic material "loose tube", characterized by the combination of the protective sheath (4). ) is coated with a micro-band (5), preferably a micro-band on a glass carrier, and the protective sheath (4) between itself and the optical fiber (2a-2d) contains a material (3) which prevents oxidation of the optical fiber and gives get residuals in case of fire, e.g. modified silicone grease, which, on fire, forms fine quartz powder which retains a supporting function of the fiber, the mic strip (5) forming a sintered tube which replaces the sheath (4) and holding the quartz powder in place around the fiber (2a-2d).

Fiber cable according to claim 1, characterized in that a layer of glass ribbon (6) is arranged on one or more elements of the protective sheath (4) coated with micro-tape (5).

Fiber cable according to claim 1 or 2, characterized in that a filler jacket (7) with good fire-retardant properties is enclosed on the outside of the protective tube (s) (4) with the fire-retardant coating (5) and glass ribbon (6).

Fiber cable according to claim 3, characterized in that a reinforcement, braid, wrap or ribbon (8) of glass, steel or other fire-resistant material is placed on the outside of the filler cap (7).

Fiber cable according to any one of the preceding claims, characterized in that the cable has a core (1) of steel, fiber-reinforced plastic or glass.