US4661687A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for converting a fluid tracing system into an electrical tracing system
Assignee: Raychem Corp
•
Filing: 1985-05-09
•
Granted: 1987-04-28
•
Expires: 2005-05-09
Abstract
Abstract A method and apparatus for converting a fluid tracing system, e.g., a thermally insulated steam heat tracing system for a substrate, into an electrical heat tracing system for the substrate. A typical steam tracing system includes a substrate to be heated; an interconnecting system of steam tracing tubes adjacent to and in thermal contact with the substrate; and thermal insulation surrounding the substrate and steam tracing tubes. The conversion method includes the steps of removing the thermal insulation at spaced-apart locations and opening up the plurality of interconnected tubes so that elongate electrical heating elements can be inserted into the tubes, inserting elongate electrical heating elements into the tubes, and connecting the elongate electrical heating elements to a power supply in order to heat the substrate. Preferably, a gel-forming liquid is introduced into the elongate tubes and is converted into a gel within the tubes.
Inventors
- 👤 Khosrow Afkhampour
- 👤 Neville S. Batliwalla
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 07:02
CPC Classifications
H; H05; H05B; H05B3/00; H05B3/40; H05B3/54; H05B3/58; F; F16; F16L; F16L53/00; F16L53/30; F16L53/35; F16L53/38
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
125 words
Apparatus comprising (a) a substrate to be heated; (b) a plurality of interconnected elongate tubes which are adjacent to and in thermal contact with said substrate, at least some of said tubes having once formed part of a former heating system for said substrate, in which system a heated fluid was passed through the tubes and thermal insulation surrounded the tubes and the substrate; (c) an elongate electrical heating element which lies within and extends along said elongate tubes and which can be connected to a power supply to provide an elongate electrical heater; and (d) thermal insulation which surrounds the elongate tubes and the substrate, at least part of said thermal insulation being the same as the thermal insulation in said former heating system.
Claim 2
Dependent Claim
125 words
Apparatus comprising (a) a substrate to be heated; (b) a plurality of interconnected elongate tubes which are adjacent to and in thermal contact with said substrate, at least some of said tubes having once formed part of a former heating system for said substrate, in which system a heated fluid was passed through the tubes and thermal insulation surrounded the tubes and the substrate; (c) an elongate electrical heating element which lies within and extends along said elongate tubes and which can be connected to a power supply to provide an elongate electrical heater; and (d) thermal insulation which surrounds the elongate tubes and the substrate, at least part of said thermal insulation being the same as the thermal insulation in said former heating system.
Claim 3
Dependent Claim
16 words
Apparatus according to claim 1 wherein the tubes have a 0.25 to 2 inch inner diameter.
Claim 4
Dependent Claim
30 words
Apparatus according to claim 1 wherein the heating element comprises at least two elongate conductors and a plurality of heating elements connected in parallel with each other between the conductors.
Claim 5
Dependent Claim
20 words
Apparatus according to claim 1 wherein said heating element, when connected to a suitable power supply, is a self-regulating heater.
Claim 6
Dependent Claim
18 words
Apparatus according to claim 4 wherein the heating element comprises a conductive polymer composition which exhibits PTC behavior.
Claim 7
Dependent Claim
36 words
Apparatus according to claim 5 wherein the heating element comprises at least two elongate, spaced-apart conductors and an elongate resistive heating strip which is composed of a PTC conductive polymer and is wrapped around the conductors.
Claim 8
Dependent Claim
19 words
Apparatus according to claim 1 which further comprises (e) a power supply which is connected to the heating element.
Claim 9
Dependent Claim
25 words
Apparatus according to claim 7 wherein the power supply supplies an alternating current whose frequency is 10,000 to 100,000 Herz and whose magnitude is fixed.
Claim 10
Dependent Claim
14 words
Apparatus according to claim 8 wherein said fixed magnitude is 5 to 40 amps.
Claim 11
Dependent Claim
20 words
Apparatus according to claim 1 wherein the heating element is a series heating element comprising a low resistance return conductor.
Claim 12
Dependent Claim
36 words
Apparatus according to claim 10 wherein the return conductor comprises said plurality of interconnected elongate tubes containing the heating element or a second plurality of interconnected elongate tubes which once formed part of said heating system.
Claim 13
Dependent Claim
23 words
Apparatus according to claim 1 which further comprises (e) a gel which lies between the heating element and the tube surrounding the element.
Claim 14
Dependent Claim
16 words
Apparatus according to claim 12 wherein said gel comprises a particulate thermally conductive filler dispersed therein.
Claim 15
Dependent Claim
21 words
Apparatus according to claim 12 wherein the gel is a polymeric material which has been cross-linked in situ in the tube.
Claim 16
Dependent Claim
17 words
Apparatus according to claim 12 wherein the gel is a polysiloxane, a polyurethane, or a butyl rubber.
Claim 17
Independent Claim
127 words
A method of converting a thermally insulated steam heat-tracing system for a substrate into an electrical system for the substrate, said steam heat-tracing system comprising a substrate, a plurality of interconnected elongate tubes adjacent to and in thermal contract with the substrate so as to permit steam to be passed through the tubes in order to warm the substrate, and thermal insulation surrounding the elongate tubes and the substrate, which method comprises (1) at spaced-apart locations, removing the thermal insulation and opening up the plurality of interconnected tubes so that elongate electrical heating elements can be inserted into said tubes, (2) inserting elongate electrical heating elements into said tubes, and (3) connecting said elongate electrical heating elements to a power supply in order to heat the substrate.
Claim 18
Independent Claim
127 words
A method of converting a thermally insulated steam heat-tracing system for a substrate into an electrical system for the substrate, said steam heat-tracing system comprising a substrate, a plurality of interconnected elongate tubes adjacent to and in thermal contract with the substrate so as to permit steam to be passed through the tubes in order to warm the substrate, and thermal insulation surrounding the elongate tubes and the substrate, which method comprises (1) at spaced-apart locations, removing the thermal insulation and opening up the plurality of interconnected tubes so that elongate electrical heating elements can be inserted into said tubes, (2) inserting elongate electrical heating elements into said tubes, and (3) connecting said elongate electrical heating elements to a power supply in order to heat the substrate.
Claim 19
Dependent Claim
41 words
A method according to claim 16 wherein each of said elongate heating elements is a self-regulating heating element which comprises at least two elongate conductors and a plurality of self-regulating heating elements connected in parallel with each other between the conductors.
Claim 20
Dependent Claim
40 words
A method according to claim 17 wherein each of said elongate heating elements comprises at least two elongate, spaced-apart conductors and an elongate resistive heating strip which is composed of a PTC conductive polymer and is wrapped around the conductors.
Claim 21
Dependent Claim
25 words
A method according to claim 18 wherein a gel-forming liquid is introduced into the elongate tubes and is converted into a gel within the tubes.
Claim 22
Dependent Claim
15 words
A method according to claim 19 wherein the liquid comprises a particulate thermally conductive filler.
Claim 23
Dependent Claim
19 words
A method according to claim 19 wherein the liquid comprises precursors for a polysiloxane, polyurethane or butyl rubber gel.
References Cited (Backward Citations)
US3315703A
Cited
US2783351A
Cited
US2938993A
Cited
GB1179039A
Cited
DE2157530A1
Cited
FR2257185A1
Cited
US4002881A
Cited
US4203186A
Cited
US4117312A
Cited
GB2047510A
Cited
EP0021597A2
Cited
US4401156A
Cited
US4459473A
Cited
WO1984002048A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-04-27 | 1990-10-27 | 1991-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-04-27 | 1994-10-27 | 1995-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-04-27 | 1998-10-27 | 1999-04-28 | $7700.00 | Window Closed / Lapsed |