Patent US3236622A successfully refreshed from Google Patents.
Patent US4284842A successfully refreshed from Google Patents.
US4284842A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cable having superior resistance to flame spread and smoke evolution
Assignee: AT&T Inc
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Filing: 1979-10-31
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Granted: 1981-08-18
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Expires: 1999-10-31
Abstract
Abstract A cable (20) specially suited for use in building plenums because of its low flame spread and smoke evolution includes a multiconductor core (22) which is enclosed in a sheath comprising an inorganic, cellular core wrap (31), a corrugated metallic barrier (40) and dual layers (51) and (52) of a polyimide tape which are wrapped helically about the barrier in a manner that avoids a compression of the core wrap. The sheath is effective to resist heat transfer inwardly toward the core by conduction while the metallic barrier reflects radiant heat. Advantageously, the sheath containerizes the core without unduly compressing it and thereby allows the intumescence of conductor insulation during a fire to form char which is effective to suppress the evolution of smoke and the propagation of flame.
Inventors
- 👤 Candido J. Arroyo
- 👤 Nicholas J. Cogelia
- 👤 Ralph J. Darsey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:08
CPC Classifications
H; H01; H01B; H01B7/00; H01B7/17; H01B7/29; H01B7/295
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
150 words
A cable which resists flame spread and smoke evolution, said cable comprising: a core which includes an insulated conductor; a layer which encloses the core and which comprises an inorganic, cellular material; a metallic barrier which encloses said cellular layer and which comprises a strip having longitudinal edge portions formed into a seam, said metallic barrier having an outwardly facing surface which has a relatively low emissivity; and an outer cover of a flame retardant material which encloses said metallic barrier and which comprises: a first tape comprising a thermosetting material having at least translucent optical clarity and having a relatively low thermal diffusivity, said first tape wrapped about the barrier with an overlapped sealed seam; and a second tape comprising a thermosetting material having at least translucent optical clarity and having a relatively low thermal diffusivity, said second tape wrapped about said first tape with an overlapped sealed seam.
Claim 2
Dependent Claim
150 words
A cable which resists flame spread and smoke evolution, said cable comprising: a core which includes an insulated conductor; a layer which encloses the core and which comprises an inorganic, cellular material; a metallic barrier which encloses said cellular layer and which comprises a strip having longitudinal edge portions formed into a seam, said metallic barrier having an outwardly facing surface which has a relatively low emissivity; and an outer cover of a flame retardant material which encloses said metallic barrier and which comprises: a first tape comprising a thermosetting material having at least translucent optical clarity and having a relatively low thermal diffusivity, said first tape wrapped about the barrier with an overlapped sealed seam; and a second tape comprising a thermosetting material having at least translucent optical clarity and having a relatively low thermal diffusivity, said second tape wrapped about said first tape with an overlapped sealed seam.
Claim 3
Dependent Claim
38 words
The cable of claim 1, wherein said layer of inorganic, cellular material which encloses the core is capable of being compressed to allow expansion of the insulation of the conductors when said insulation intumesces when exposed to heat.
Claim 4
Dependent Claim
23 words
The cable of claim 1, wherein said layer of inorganic, cellular material is wrapped about the core to form a longitudinal overlapped seam.
Claim 5
Dependent Claim
26 words
The cable of claim 1, wherein said cellular layer comprises a glass based tape with the diameter of each fiber being not less than six microns.
Claim 6
Dependent Claim
15 words
The cable of claim 1, wherein said barrier is formed from a corrugated aluminum tape.
Claim 7
Dependent Claim
40 words
The cable of claim 1, wherein said metallic barrier and said first and second tapes of said outer cover are disposed about said cellular layer without substantial compression of said barrier to preserve the cellular structure of said cellular layer.
Claim 8
Dependent Claim
21 words
The cable of claim 1, wherein said metallic barrier is wrapped about said core to form a longitudinal overlapped unsealed seam.
Claim 9
Dependent Claim
25 words
The cable of claim 1, wherein said outwardly facing surface of said metallic barrier has an emissivity in the range of about 0.039 to 0.057.
Claim 10
Dependent Claim
26 words
The cable of claim 1, wherein the thermal diffusivity of each of said tapes is in the range of about 0.0008 to 0.001 cm 2 /sec.
Claim 11
Dependent Claim
39 words
The cable of claim 1, wherein each said tape is wrapped helically about the enclosed core so that each turn of said each tape overlaps at least about fifty percent of a preceding turn of the same said tape.
Claim 12
Dependent Claim
19 words
The cable of claim 10, wherein said first and said second tapes are made of a polyimide plastic material.
Claim 13
Dependent Claim
34 words
The cable of claim 1 wherein each of said tapes has at least a portion of at least one major surface coated with an adhesive that seals the seam and does not burn prematurely.
Claim 14
Dependent Claim
33 words
The cable of claim 12, wherein an outwardly facing surface of said first tape is coated with an adhesive and an inwardly facing surface of said second tape is coated with an adhesive.
Claim 15
Dependent Claim
24 words
The cable of claim 13, wherein the thermal diffusivity of said adhesive is in the range of about 0.0008 to 0.001 cm 2 /sec.
Claim 16
Dependent Claim
29 words
The cable of claim 8, wherein said first and second tapes have at least a portion of at least one major surface coated with a fluorinated ethylene propylene adhesive.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-08-17 | 1985-02-16 | 1985-08-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-08-17 | 1989-02-16 | 1989-08-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-08-17 | 1993-02-16 | 1993-08-18 | $7700.00 | Window Closed / Lapsed |