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WO1999048113A1 - Cables - Google Patents

Cables

Info

Publication number
WO1999048113A1
WO1999048113A1 PCT/GB1999/000743 GB9900743W WO9948113A1 WO 1999048113 A1 WO1999048113 A1 WO 1999048113A1 GB 9900743 W GB9900743 W GB 9900743W WO 9948113 A1 WO9948113 A1 WO 9948113A1
Authority
WO
WIPO (PCT)
Prior art keywords
cable
blowing agent
chemical blowing
gas
insulation
Prior art date
Application number
PCT/GB1999/000743
Other languages
English (en)
Inventor
Gregor Reid
Mark Froggatt
David Kemp
Original Assignee
Draka U.K. Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Draka U.K. Limited filed Critical Draka U.K. Limited
Priority to AU27404/99A priority Critical patent/AU2740499A/en
Publication of WO1999048113A1 publication Critical patent/WO1999048113A1/fr

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
    • G02B6/4401—Optical cables
    • G02B6/4429—Means specially adapted for strengthening or protecting the cables
    • G02B6/4436—Heat resistant
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/29—Protection against damage caused by extremes of temperature or by flame
    • H01B7/295—Protection against damage caused by extremes of temperature or by flame using material resistant to flame

Definitions

  • the present invention relates to cables .
  • Cables for example, electric power cables, and cables that transport electrical signals or data, and optical fibres, are required to link parts of buildings. They are often laid in cavities or conduits which give free passage through walls, floors and ceilings.
  • the materials that are used as electrical insulation m electric cables or as protective coatings for optical fibres are often of a type that supports combustion.
  • a fire a problem is caused if the insulation or coating of the cable is set alight. The fire can be quickly propagated along the cable through the conduits, passing under or through walls and thus spreading the fire. This will prevent containment of the fire resulting in rapid flame spread leading to increased damage to the building and greater endangerment to life. It is particularly important to reduce flame spread m areas of high airflow, for example ventilation shafts and plenums.
  • a cable comprises at least one conductor, and a layer or layers of material surrounding the conductor, the material including a material that evolves gas when the temperature is raised above normal ambient temperature to a temperature such as is experienced m the event of a fire.
  • the gas or gases evolved at elevated temperatures may retard flame spread by one or more of the following actions: by causing an increase m the cable volume which creates a physical barrier to flame spread, by causing the cable sheath to become discontinuous thus reducing the fuel for flame spread, or by introducing a non-flammable gas which displaces oxygen from around the cable and thus suffocates the flames.
  • the conductor is an electric conductor and the layer or layers of material will include electrical insulation.
  • the conductor is an optical fibre or bundle of optical fibres and the layers of material will include a coating to protect the optical fibre.
  • the material that evolves gas at elevated temperatures is a chemical blowing agent.
  • a chemical blowing agent is a material that produces a gas or gases, by its chemical decomposition, forming a cellular structure m a polymeric matrix.
  • the decomposition process is usually exothermic, irreversible and takes place at elevated temperature, but m the case of certain chemical blowing agents, gas or gases are released by an endothermic reaction between two components.
  • Examples of chemical blowing agents that evolve a gas or gases at suitable elevated temperatures include: sodium bicarbonate, azodicarbonamide, dmitrosopentamethylenetetramine, 4,4' -oxy-bis- (benzenesulphonylhydrazide) , trihydrazinot ⁇ az ne, modified azodicarbonamide, N,N dimethyl N, N dinitrosoterephthalamide or 5-phenyl tetrazole .
  • the chemical blowing agent evolves a gas or gases that are non-flammable and/or non-toxic.
  • the chemical blowing agent decomposes at a temperature above 180°C.
  • gases that are evolved by suitable chemical blowing agents are nitrogen, carbon dioxide, water (in the form of steam) and ammonia or a combination of some or all of the aforementioned gases.
  • the chemical blowing agent will have a gas evolution of between 50 - 500 millilitres at normal atmospheric pressure per gram.
  • the material that evolves gas may be located within the insulation material, between the conductor and the layer of insulation, between further discrete layers of insulation within the insulation layer, or between the insulating layer and an external, sheath layer.
  • the material that evolves gas is formed as a separate layer it may be provided on a tape such as mica tape, or it may be incorporated into the cable by one or more of the following techniques: by surface dusting; by solution coating; or by spray coating.
  • material that evolves gas at elevated temperatures is arranged in the cable that evolution of the gas causes at least a part of the insulation to become discontinuous.
  • the material that evolves gas may be located so that when the gas is evolved, at least a part of the insulating layer is maintained around the conductor, enabling electrical performance of the cable to be maintained at elevated temperature.
  • the chemical blowing agent may be used m conjunction with an initiator or 'kicker' such as, for example, zinc stearate, calcium stearate, zinc oxide, or other metal salts.
  • the initiator promotes decomposition of the chemical blowing agent at the decomposition temperature of the chemical blowing agent.
  • FIGURE 1 shows, in diagrammatic form, a section through a building showing a cable conduit
  • FIGURE 2 shows the cable conduit of figure 1 after exposure to a fire for a short period of time
  • FIGURE 3 shows, on an enlarged scale, a detailed cross section of a cable according to one embodiment of the present invention
  • FIGURE 4 shows, on an enlarged scale, a detailed cross section of a cable according to a second embodiment of the present invention
  • FIGURE 5 shows, on an enlarged scale, a detailed cross section of a cable according to a further embodiment of the present invention.
  • FIGURE 6 shows, on an enlarged scale, a cable conduit provided with a cable according to an embodiment of the present invention
  • FIGURE 7 shows a section through a cable conduit provided with a cable according to a further embodiment of the present invention.
  • FIGURE 8 shows a section through a cable conduit provided with a cable according to a further embodiment of the present invention.
  • Figure 1 shows a fragmentary view of a building with a cable conduit 2 containing a cable 1.
  • the conduit leads through a wall 4 between adjoining rooms 6 and 9.
  • a fire 3 has occurred m room 6 and is in the process of burning part of cable 1.
  • Figure 2 shows the same cable conduit as m figure 1 after the cable 1 has been exposed to the fire 3 for a short period.
  • the cable insulation or coating has caught light and the flame 5 has spread along the cable. Flames 5 have travelled along the cable through 6 wall 4 via the conduit 2 and into the adjacent room 9.
  • FIG. 3 shows a cross section of an electric cable 11 according to one embodiment of the present invention.
  • the cable 11 has a copper conductor 10, surrounded by insulating layers 14,15.
  • the outer insulating layer is surrounded by sheath 16.
  • One or more of the insulating layers may be a polymeric insulating layer.
  • One or more of the layers 14, 15, 16 is of a material that supports combustion in the event of a fire. Examples of materials suitable for use as insulating layers 14,15 are silicone rubber, polyethylene and glass/mica tape.
  • the outer sheath layer 16 may be a zero halogen, low smoke type protective layer.
  • a chemical blowing agent is incorporated into the formulation of one or both of insulation layers 14 or 15. Examples of suitable chemical blowing agents that evolve a gas or gases at elevated temperatures include : sodium bicarbonate, azodicarbonamide, dinitrosopentamethylenetetramme,
  • Figure 4 shows a cross section of a cable according to a further embodiment of the present invention, m which parts similar to the previous embodiment are denoted by like numbers.
  • the chemical blowing agent in this embodiment is incorporated as a discrete layer 17 between the insulating layer 15 and the outer sheath 16.
  • the chemical blowing agent may be impregnated into a layer of glass tape, or as a dusting/coating layer deposited on the layer 15.
  • the chemical blowing agent may be located as a discrete layer between the conductor 10 and the insulation layer 14, or between the insulation layers 14 and 15.
  • the chemical blowing agent is present in the cable as an impregnated tape 17, it may be applied to the cable by a method such as winding or wrapping, rather than by extrusion.
  • the former methods of application have the advantage that the chemical blowing agent is not heated when being applied onto the cable, and there is thus less risk that the chemical blowing agent may be activated prematurely, for example during manufacture .
  • Figure 5 shows a cross section of a cable 11 according to a further embodiment of the present invention.
  • the chemical blowing agent in this embodiment is incorporated into the formulation of the outer sheath 16.
  • Figures 6 to 8 illustrate how cables according to the invention might behave when exposed to the elevated temperatures associated with a fire.
  • Figure 6 shows a cable conduit equipped with a cable 1 ' according to the present invention.
  • the cable 1' has been exposed to a fire.
  • the high temperatures have 8 activated the chemical blowing agent, causing the chemical blowing agent to evolve gas.
  • the gas generated causes the cable coating to swell to form a bulge 7, thereby providing a physical barrier to flame spread and heat propagation along the cable 11.
  • the outer surface of cable When exposed to a fire, the outer surface of cable, for example the sheath layer, will become charred at area 8.
  • the charred area will not burn any further after it has become charred, thus forming a further physical barrier at the surface of the cable that protects the underlying insulation layers 14,15 and prevents any further insulation being burnt; the charring therefore reduces the amount of fuel that can come into contact with the flames.
  • Figure 7 shows a cable conduit equipped with a cable 1" according to the present invention.
  • a chemical blowing agent is included in the cable.
  • the cable has been exposed to a fire and the elevated temperatures have caused the chemical blowing agent to evolve gas .
  • the gas generated may make the cable coating shatter into fragments 12a, thus removing fuel from the proximity of the flames, or may crack the sheath thus making it discontinuous as illustrated in area 12b.
  • Figure 8 shows a cable conduit equipped with a cable 1 ' " according to a further embodiment of the present invention.
  • the cable includes a chemical blowing agent.
  • the chemical blowing agent evolves a gas because of the elevated temperatures.
  • the gas may remove oxygen from the immediate proximity of the cable sheath and replace the oxygen with a non-flammable gas such as, for example, nitrogen, carbon dioxide, water (m the form of steam), ammonia, or a combination of some or all of the aforementioned gases.
  • a non-flammable gas such as, for example, nitrogen, carbon dioxide, water (m the form of steam), ammonia, or a combination of some or all of the aforementioned gases.
  • the gas or gases evolved may also be flame retardant, thus having an additional fire quenching effect .
  • the cable When exposed to a fire, the cable might behave in one or more of the ways illustrated in figures 6 to 8 and described in the accompanying text.
  • the behaviour may depend on one or more combinations of the following factors:
  • the temperature profile experienced by the cable within the fire (for example behaviour may depend on the rate of temperature change and whether the heating is localised or over a large area of the cable) .

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Insulated Conductors (AREA)

Abstract

L'invention concerne un câble électrique (11) qui comprend un conducteur en cuivre (10) entouré de couches isolantes (14, 15) et une gaine externe (16). Une des couches isolantes (14 ou 15) comprend un agent de blanchiment chimique qui dégage un gaz ou des gaz à des températures élevées. Une des couches isolantes (14, 15, 16) est constituée d'un matériau qui supporte la combustion. En cas de feu, l'agent de blanchiment chimique est activé pour éliminer les gaz qui gonflent le câble afin de former un renflement (7). Le renflement (7) sert de barrière physique à la propagation des flammes et de la chaleur le long du câble.
PCT/GB1999/000743 1998-03-13 1999-03-12 Cables WO1999048113A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU27404/99A AU2740499A (en) 1998-03-13 1999-03-12 Cables

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9805442.2 1998-03-13
GB9805442A GB2335304A (en) 1998-03-13 1998-03-13 Electric or optic cable which evolves gas for fire protection

Publications (1)

Publication Number Publication Date
WO1999048113A1 true WO1999048113A1 (fr) 1999-09-23

Family

ID=10828543

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1999/000743 WO1999048113A1 (fr) 1998-03-13 1999-03-12 Cables

Country Status (3)

Country Link
AU (1) AU2740499A (fr)
GB (1) GB2335304A (fr)
WO (1) WO1999048113A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2238578C1 (ru) * 2003-10-08 2004-10-20 Общество с ограниченной ответственностью "ПетроЛайт" Волоконно-оптический кабель для измерения температурного распределения в паронагнетательных скважинах
CN112670020A (zh) * 2020-12-15 2021-04-16 刘金桥 一种自防护型防火电缆

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2436395A (en) * 2006-03-24 2007-09-26 Tyco Electronics A heat resistant cable

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2105096A1 (en) * 1971-02-04 1972-08-10 Felten & Guilleaume Kabelwerk Flame-protective materials - esp for cables, contg carbohydrates or cellulose ethers as blowing agents
EP0017609A1 (fr) * 1979-04-10 1980-10-15 Siemens Aktiengesellschaft Câble électrique ou optique à isolation en matière synthétique, comprenant un manteau intérieur résistant à la flamme
DE3409369A1 (de) * 1984-03-12 1985-09-19 Siemens AG, 1000 Berlin und 8000 München Kabelmantel fuer ein nachrichtenkabel
WO1998003052A2 (fr) * 1996-07-08 1998-01-29 Nu-Chem, Inc. Compositions de protection thermique contenant du platine

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3576388A (en) * 1968-12-05 1971-04-27 Stauffer Wacker Silicone Corp Electrical cable
DE2907473A1 (de) * 1979-02-26 1980-09-04 Kabel Metallwerke Ghh Elektrisches kabel

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2105096A1 (en) * 1971-02-04 1972-08-10 Felten & Guilleaume Kabelwerk Flame-protective materials - esp for cables, contg carbohydrates or cellulose ethers as blowing agents
EP0017609A1 (fr) * 1979-04-10 1980-10-15 Siemens Aktiengesellschaft Câble électrique ou optique à isolation en matière synthétique, comprenant un manteau intérieur résistant à la flamme
DE3409369A1 (de) * 1984-03-12 1985-09-19 Siemens AG, 1000 Berlin und 8000 München Kabelmantel fuer ein nachrichtenkabel
WO1998003052A2 (fr) * 1996-07-08 1998-01-29 Nu-Chem, Inc. Compositions de protection thermique contenant du platine

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2238578C1 (ru) * 2003-10-08 2004-10-20 Общество с ограниченной ответственностью "ПетроЛайт" Волоконно-оптический кабель для измерения температурного распределения в паронагнетательных скважинах
CN112670020A (zh) * 2020-12-15 2021-04-16 刘金桥 一种自防护型防火电缆

Also Published As

Publication number Publication date
AU2740499A (en) 1999-10-11
GB2335304A (en) 1999-09-15
GB9805442D0 (en) 1998-05-13

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