GB2267395A - Electric and optical cables and installations thereof - Google Patents
Electric and optical cables and installations thereof Download PDFInfo
- Publication number
- GB2267395A GB2267395A GB9210943A GB9210943A GB2267395A GB 2267395 A GB2267395 A GB 2267395A GB 9210943 A GB9210943 A GB 9210943A GB 9210943 A GB9210943 A GB 9210943A GB 2267395 A GB2267395 A GB 2267395A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cable
- species
- bark
- fibres
- sequoia
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 7
- 238000009434 installation Methods 0.000 title description 3
- 239000000463 material Substances 0.000 claims abstract description 19
- 241000256602 Isoptera Species 0.000 claims abstract description 16
- 239000000284 extract Substances 0.000 claims abstract description 14
- 239000005871 repellent Substances 0.000 claims abstract description 13
- 241000894007 species Species 0.000 claims abstract description 13
- 241001116459 Sequoia Species 0.000 claims abstract description 11
- 241000422847 Sequoiadendron Species 0.000 claims abstract description 11
- 230000002940 repellent Effects 0.000 claims abstract description 9
- 239000004744 fabric Substances 0.000 claims abstract description 7
- 239000000654 additive Substances 0.000 claims abstract description 6
- 239000000945 filler Substances 0.000 claims abstract description 3
- 235000013312 flour Nutrition 0.000 claims abstract description 3
- 239000010410 layer Substances 0.000 claims description 5
- 230000000996 additive effect Effects 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 229920000642 polymer Polymers 0.000 claims description 3
- 239000011241 protective layer Substances 0.000 claims description 3
- 229920002994 synthetic fiber Polymers 0.000 claims description 3
- 239000004753 textile Substances 0.000 claims description 3
- TUSDEZXZIZRFGC-UHFFFAOYSA-N 1-O-galloyl-3,6-(R)-HHDP-beta-D-glucose Natural products OC1C(O2)COC(=O)C3=CC(O)=C(O)C(O)=C3C3=C(O)C(O)=C(O)C=C3C(=O)OC1C(O)C2OC(=O)C1=CC(O)=C(O)C(O)=C1 TUSDEZXZIZRFGC-UHFFFAOYSA-N 0.000 claims description 2
- 239000001263 FEMA 3042 Substances 0.000 claims description 2
- LRBQNJMCXXYXIU-PPKXGCFTSA-N Penta-digallate-beta-D-glucose Natural products OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-PPKXGCFTSA-N 0.000 claims description 2
- 238000011065 in-situ storage Methods 0.000 claims description 2
- LRBQNJMCXXYXIU-NRMVVENXSA-N tannic acid Chemical compound OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-NRMVVENXSA-N 0.000 claims description 2
- 229940033123 tannic acid Drugs 0.000 claims description 2
- 235000015523 tannic acid Nutrition 0.000 claims description 2
- 229920002258 tannic acid Polymers 0.000 claims description 2
- 229920001864 tannin Polymers 0.000 claims description 2
- 235000018553 tannin Nutrition 0.000 claims description 2
- 239000001648 tannin Substances 0.000 claims description 2
- 241001138418 Sequoia sempervirens Species 0.000 abstract description 5
- 235000003499 redwood Nutrition 0.000 abstract description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000004615 ingredient Substances 0.000 description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- 229920001577 copolymer Polymers 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000004952 Polyamide Substances 0.000 description 1
- 241000422846 Sequoiadendron giganteum Species 0.000 description 1
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 150000001720 carbohydrates Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- DFBKLUNHFCTMDC-PICURKEMSA-N dieldrin Chemical compound C([C@H]1[C@H]2[C@@]3(Cl)C(Cl)=C([C@]([C@H]22)(Cl)C3(Cl)Cl)Cl)[C@H]2[C@@H]2[C@H]1O2 DFBKLUNHFCTMDC-PICURKEMSA-N 0.000 description 1
- 229950006824 dieldrin Drugs 0.000 description 1
- NGPMUTDCEIKKFM-UHFFFAOYSA-N dieldrin Natural products CC1=C(Cl)C2(Cl)C3C4CC(C5OC45)C3C1(Cl)C2(Cl)Cl NGPMUTDCEIKKFM-UHFFFAOYSA-N 0.000 description 1
- 235000005911 diet Nutrition 0.000 description 1
- 230000037213 diet Effects 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 210000004373 mandible Anatomy 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 230000007096 poisonous effect Effects 0.000 description 1
- 229920006112 polar polymer Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 235000013824 polyphenols Nutrition 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000001850 reproductive effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
- 210000002268 wool Anatomy 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G9/00—Installations of electric cables or lines in or on the ground or water
-
- 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
-
- 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
- H01B7/28—Protection against damage caused by moisture, corrosion, chemical attack or weather
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Catching Or Destruction (AREA)
Abstract
An electric or optical cable is protected from attack by termite species in an environmentally friendly and effective manner. The cable is surrounded by a layer comprising the bark of a tree selected from the genera sequoia and sequoiadendron, a termite-repellent extract characteristic of such species or a natural or synthetic equivalent of such repellent extract. The bark e.g. from the Californian redwood or giant sequoia, may be used in fibrous form in a fabric or braid, in the form of fibres or flour as a filler in polymeric sheathing material. Extracts or equivalents may be used as additives in polymeric material or as impregnants or other additives in fabric or paper-based materials. Alternatively the bark may be used as a backfill in a cable trench.
Description
ELECTRIC AND OPTICAL CABLES AND INSTALLATIONS THEREOF
This invention relates to electric and optical cables and to installations thereof. In particular it relates to cables installed or intended for installation in territories where termites are endemic. Cables in such areas are susceptible to termite damage whether they are buried in the ground or exposed and the preferred mode of protection in current use is to provide the cable with a hard, slippery surface with a curvature large enough that the mandibles of resident species of termite are unable to get a purchase on it.Suitably hard materials (metals or polyamides are generally used) are expensive compared with the cable sheathing materials used in termite-free places and especially when non-metallic material is used the protection is liable to failure because otherwise insignificant local damage creates positions of small radius where a termite attack can begin. The use of poisonous materials (such as aldrin and dieldrin) is now hardly acceptable in view of hazards to manufacturing personnel and to the environment in both the place of manufacture and the place of use, and in any event is not very effective because the number of foraging-class termites that must be killed to have any perceptible effect on the reproductive capacity of their colony is very large.
The present invention is based on the observation that termites generally avoid certain trees, namely the californian (or coastal) redwood tree (sequoia sempervirens ) and the closely related giant sequoia (or wellingtonia, sequoiadendron gigantaea)and in particular do not attack the bark of these trees. While the applicants do not wish to be bound by any theory, there seems to be some evidence for the proposition that sequoiaphagic activity in termites would be maladaptive because the tree is harmful to, or at least does not provide an adequate diet for, the symbiotic protozoa on which termites depend for their ability to digest and subsist on dead wood.
It has been proposed (US-A-3285810) to use a blanket of redwood bark wool on the sub-floor to inhibit termite attack on timber buildings, but the potential for adaptation to the protection of electric and optical cables has not hitherto been appreciated.
In accordance with the present invention, an electric or optical cable is protected from attack by termite species by a surrounding layer comprising the bark of a tree selected from the genera sequoia and sequoiadendron, a termite-repellent extract characteristic of such species or a natural or synthetic equivalent of such repellent extract, all hereinafter for brevity included in the expression "seqoia repellent".
The invention includes a cable of conventional construction installed in a trench in which it is surrounded by a backfill material comprising the said sequoia repellent. Preferably, however, the sequoia repellent is incorporated into the outer layer of the cable structure.
Bark of sequoia sempervirens is more readily available than the other species of the genera, as the timber of the tree is in regular use for building purposes.
In one form of the invention, bark of the chosen species is reduced to fibres which are either spun into a yarn and woven into a coarse fabric or else formed into a needled felt or a laid paper which is in each case lapped (or longitudinally applied an fixed down) onto an otherwise complete cable (as bitumenised hessian is sometimes so applied for other protective purposes); or it may be feasible to form a seamless braid of such yarn in situ on some forms of cable. In either case the yarn (and/or the fabric in the first case) may incorporate fibres from more than one sequoia or sequoiadendron species and/or natural or synthetic fibres with better mechanical properties.
In another form of the invention, bark from the chosen species is reduced to fibres and/or flour and incorporated as filler into a polymer-based material which is extruded as a tubular sheath forming the outer layer of a cable or as a tape which is subsequently lapped about a cable. Preferably at least a proportion of the bark is in particles coarse enough to ensure exposure of bark particles at the surface, where they may be more easily and rapidly recognised by termites than if they are covered by a skin of polymeric material. The polymer base should be chosen for good compatibility with the bark material: our present preference is for a composition based on copolymers of ethylene with one or more relatively polar polymers (for example ethylene/vinyl acetate and ethylene/ethyl acrylate copolymers.
While the use of extracts or their natural or synthetic equivalents is likely to increase cost, it may also prove to offer the possibility of using a higher level of repellent material than is present in the natural bark; or of better compatibility with a textile or other polymeric carrier resulting in a tougher protective layer; or of avoiding undesirable properties of the natural bark, such as a degree of water absorption; or more than one of these advantages.
The relevant extract or extracts has not yet been positively identified, but his demands no more than routine trial-and-error experimentation. It may be that more than one ingredient of the bark of these species is implicated, either in the sense that each is effective in suitable concentration to repel termites or in the sense that more than one ingredient is necessary to enable termites to recognise a material they are "programmed" to avoid. At present we are considering the possibility that tannin (or tannic acid - a complex carbohydrate ether-ester, possibly containing free phenolic hydroxyl groups) and/or one or more than one ingredient extractable with methanol from the said barks is an effective termite repellant. It will be understood that although the repellent material appears to be present in the greatest cancentration in the bark of these species, it may be possible or even preferable to extract them from other parts of the tree, or to find other natural sources or to synthesise the termite-repellent substance(s) once they have been identified.
The invention thus includes a third form, namely a cable in which one or more of these or other extracts from sequoia or sequoiadendron species (or a natural synthetic equivalent) is used in the form of an additive to polymeric material or as an impregnant or other additive in a textile or paper base material to form the outer protective layer of the cable.
Claims (12)
1 An electric or optical cable protected from attack by termite species by a surrounding layer comprising a sequoia repellent, namely the bark of a tree selected from the genera sequoia and sequoiadendron, a termite-repellent extract characteristic of such species or a synthetic equivalent of such repellent extract.
2 A cable as claimed in claim 1 in which bark of the said species is reduced to fibres which are either spun into a yarn and woven into a coarse fabric or formed into a needled felt or a laid paper which is in each case lapped (or longitudinally applied and fixed down) onto an otherwise complete cable.
3 A cable as claimed in claim 1 in which bark of the said species is reduced to fibres which are spun ito yarn and formed into a seamless braid in situ on the cable.
4 A cable as claimed in Claim 2 or claim 3 in which the said yarn incorporates fibres from more than one sequoia or sequoiadendron species.
5 A cable as claimed in any one of claims 2-4 in which the said yarn incorporates also natural or synthetic fibres with better mechanical properties.
6 A cable as claimed in Claim 2 in which the said fabric incorporates fibres from more than one sequoia or sequoiadendron species.
7 A cable as claimed in claim 2 or claim 6 in which the said fabric incorporates also natural or synthetic fibres with better mechanical properties.
8 A cable as claimed in claim 1 in which bark of the said species, reduced to fibres and/or flour, is incorporated as filler into an extruded polymer-based material forming a tubular sheath as the outer layer of a cable or a tape lapped about the cable.
9 A cable as claimed in claim 8 in which at least a proportion of the bark is in particles coarse enough to ensure exposure of bark particles at the surface of the polymeric material.
10 A cable in which one or more then one extract from a species selected from the genera sequoia and sequoiadendron (or an equivalent) is used in the form of an additive to polymeric material or as an impregnant or other additive in a textile or paper base material to form an outer protective layer of the cable.
11 A cable as claimed in claim 10 in which the said extract (or an equivalent) is a tannin or tannic acid.
12 A cable as claimed in claim 10 in which the said extract is methanol-soluble.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9210943A GB2267395A (en) | 1992-05-22 | 1992-05-22 | Electric and optical cables and installations thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9210943A GB2267395A (en) | 1992-05-22 | 1992-05-22 | Electric and optical cables and installations thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9210943D0 GB9210943D0 (en) | 1992-07-08 |
| GB2267395A true GB2267395A (en) | 1993-12-01 |
Family
ID=10715901
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9210943A Withdrawn GB2267395A (en) | 1992-05-22 | 1992-05-22 | Electric and optical cables and installations thereof |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2267395A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0760599A1 (en) * | 1994-05-16 | 1997-03-12 | McCormac, Dennis J. doing business as Safe-Tee Chemical Products Company | Environmentally safe insecticide |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3285810A (en) * | 1964-11-04 | 1966-11-15 | Virginia L Hart | Method for preventing termite infesta tion in structures |
| US4220688A (en) * | 1978-08-31 | 1980-09-02 | Ralph Mitchell | Protecting wood from wood degrading organisms |
-
1992
- 1992-05-22 GB GB9210943A patent/GB2267395A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3285810A (en) * | 1964-11-04 | 1966-11-15 | Virginia L Hart | Method for preventing termite infesta tion in structures |
| US4220688A (en) * | 1978-08-31 | 1980-09-02 | Ralph Mitchell | Protecting wood from wood degrading organisms |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0760599A1 (en) * | 1994-05-16 | 1997-03-12 | McCormac, Dennis J. doing business as Safe-Tee Chemical Products Company | Environmentally safe insecticide |
| EP0760599A4 (en) * | 1994-05-16 | 1999-05-06 | Mccormac Dennis J Doing Busine | Environmentally safe insecticide |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9210943D0 (en) | 1992-07-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |