US3201738A - Electrical heating element and insulation therefor - Google Patents
Electrical heating element and insulation therefor Download PDFInfo
- Publication number
- US3201738A US3201738A US241378A US24137862A US3201738A US 3201738 A US3201738 A US 3201738A US 241378 A US241378 A US 241378A US 24137862 A US24137862 A US 24137862A US 3201738 A US3201738 A US 3201738A
- Authority
- US
- United States
- Prior art keywords
- magnesia
- heating element
- percent
- insulation
- electrical heating
- 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.)
- Expired - Lifetime
Links
- 238000010438 heat treatment Methods 0.000 title description 17
- 238000009413 insulation Methods 0.000 title description 7
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 53
- 235000012245 magnesium oxide Nutrition 0.000 description 28
- 239000000395 magnesium oxide Substances 0.000 description 28
- 239000004020 conductor Substances 0.000 description 10
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 10
- 229910001947 lithium oxide Inorganic materials 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 230000001681 protective effect Effects 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 238000007792 addition Methods 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 239000011651 chromium Substances 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 239000011810 insulating material Substances 0.000 description 3
- 229960000869 magnesium oxide Drugs 0.000 description 3
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000010292 electrical insulation Methods 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 230000037427 ion transport Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 240000005369 Alstonia scholaris Species 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 1
- 229910018487 Ni—Cr Inorganic materials 0.000 description 1
- 229910002065 alloy metal Inorganic materials 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 229910001026 inconel Inorganic materials 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 239000010416 ion conductor Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229910001425 magnesium ion Inorganic materials 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910001120 nichrome Inorganic materials 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/40—Heating elements having the shape of rods or tubes
- H05B3/42—Heating elements having the shape of rods or tubes non-flexible
- H05B3/48—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/03—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
- H05B3/18—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor the conductor being embedded in an insulating material
Definitions
- Heating elements of the type comprising an inner, electrically resistive conductor, a surrounding layer of magnesia, electrical insulation and an outermost protective jacket are widely used in many industrial heating devices as well as in devices such as household ovens.
- This type of heating element is much more durable than, for example, exposed resistance Wire. structurally, it usually includes: (1) a coiled resistance wire composed of alloys such as those made up of l-16 percent chromium, 59-62 percent nickel, about 24 percent iron and 0.1 percent carbon; (2) compacted magnesia powder containing minor amounts of impurities surrounding the resistance coil as an insulator; and (3) an outer protective jacket normally constructed of metals ranging from lead to high temperature alloys.
- magnesia insulation breaks down and the unit becomes useless. This breakdown occurs as a result of electrical current leakage which takes place between the resistance coil and the outer jacket which is at ground potential. Thus, the potential difference causes ion transport through the magnesia insulation with electrolytic decomposition thereof. Additionally, the upper operating temperature limit has also been dependent upon the effectiveness of the magnesia insulation.
- Another object or" this invention is to provide a magnesium-oxide, lithium-oxide insulation material.
- FIG. 1 is an enlarged elevation, partly broken away, of the type of heating element with which this invention is concerned;
- FIG. 2 is a graph showing the fraction of electrolytic conductivity for doped and undoped magnesia as a function of temperature
- FIG. 3 is a graph showing the conductivity of lithiumoxide doped and undoped magnesia specimens as a function of temperature.
- this invention is concerned with a new doped magnesia composition and specifically with the use of the composition as the insulating material surrounding the heating coil or resistive conductor in a shielded heating element or unit.
- the magnesia contains small but effective amounts up to the solid solubility limit of lithiumoxide, Li O or about 0.010 mol percent.
- the purpose of the lithium-oxide additions is to reduce the ionic conduction which is felt to exist between the resistive conductor and the outer metallic protective sheet or jacket through the magnesia insulating material.
- the ionic conduction that is the carrying of current by ions, results in deterioration and eventual failure of the unit.
- ionic or electrolytic conductivity in from magnesium ion transport it has now unexpectedly been found that small amounts of lithium added to the magnesia substantially reduce the ionic electrolytic conductivity thereof at those temperatures where magnesia is predominately an ionic conductor. Specifically, ionic conduction is predominant up to about 1000 C. and then decreases as electronic conduction increases as the temperature is raised to 1500 C.
- Element 10 indicates the type of resistance heating device in which the insulation of this invention is most useful.
- Element 10 is constructed of an innermost, electrically resistive conductor 11 through which electricity flows.
- these conductors 11 are constructed in a spiral or helical form, as indicated, and are composed of high resistance alloys.
- suitable alloys include those such as Nichrome, which are high resistance alloys, composed of from 15 to 16 percent chromium, 59 to 62 percent nickel, about 24 percent iron and about 0.1 percent carbon.
- magnesia 12 Surrounding the conductor 11 is a quantity of particulate magnesia 12 which is packed tightly about conductor 11, this compaction usually being performed by a swaging operation although rolling is used occasionally.
- the magnesia normally is fairly low in impurity content, containing only several hundred parts per million of impurities such as calcium, aluminum, silicon and iron.
- the structure of the heating element is completed by an outermost metallic jacket 13 which serves to protect the elements 11 and 12 from breakage. This jacket will be constructed of some metal which is sufiiciently heat-resistant to withstand the designed operating temperature of the heating device.
- a metal such as lead can be used
- a high alloy metal such as lnconel can be used.
- Inconel is a high nickelchromium iron alloy which, in the wrought form, contains 79.5 percent nickel, 13 percent chromium, 6.5 percent iron, 0.25 percent manganese, 0.25 percent silicon, 0.8 percent carbon and 0.20 percent copper.
- curve 15 indicates the ionic conductivity of a magnesia specimen containing 0.010 mol percent dissolved lithium-oxide
- curve 16 illustrates the fraction of ionic conductivity of an undoped magnesia specimen. It is apparent by a comparison of the two curves that the fraction of ionic conductivity has been reduced in the material of curve 15. It should particularly be noted that the reduction is significant at 1000 C. which is currently the upper operating limit for most of the commercial heating devices constructed similarly to that shown in FIG. 1 of the drawing.
- the conductivity as a function of reciprocal temperature of the two specimens used to obtain Curves 15 and 16 of FIG. 2
- the magnesia which contains the lithium-oxide addition of curve 20
- An electrical resistance heating element comprising, an
- an insulating ceramic consisting of magnesiumoxide containing dissolved amounts of lithium-oxide up to the solid solubility limit thereof effective to give said insulating ceramic a fraction of ionic conductivity no higher than about 0.6 at 1000 C., said ceramic surrounding said resistive conductor, and a protective jacket enclosing said ceramic.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Resistance Heating (AREA)
- Inorganic Insulating Materials (AREA)
- Wire Processing (AREA)
- Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US241378A US3201738A (en) | 1962-11-30 | 1962-11-30 | Electrical heating element and insulation therefor |
| GB44199/63A GB1059527A (en) | 1962-11-30 | 1963-11-08 | Improvements in electrical heating elements and insulation therefor |
| DE1963G0039206 DE1465028B1 (de) | 1962-11-30 | 1963-11-20 | Elektrisches Widerstandsheizelement |
| JP6338763A JPS4317150B1 (enrdf_load_stackoverflow) | 1962-11-30 | 1963-11-25 | |
| JP44087259A JPS4817150B1 (enrdf_load_stackoverflow) | 1962-11-30 | 1969-11-01 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US241378A US3201738A (en) | 1962-11-30 | 1962-11-30 | Electrical heating element and insulation therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3201738A true US3201738A (en) | 1965-08-17 |
Family
ID=22910477
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US241378A Expired - Lifetime US3201738A (en) | 1962-11-30 | 1962-11-30 | Electrical heating element and insulation therefor |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US3201738A (enrdf_load_stackoverflow) |
| JP (2) | JPS4317150B1 (enrdf_load_stackoverflow) |
| DE (1) | DE1465028B1 (enrdf_load_stackoverflow) |
| GB (1) | GB1059527A (enrdf_load_stackoverflow) |
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3369209A (en) * | 1964-02-07 | 1968-02-13 | Edwin Bjorn | Electric heating element |
| DE1902433A1 (de) * | 1968-02-01 | 1969-08-28 | Gen Electric | Elektrisch isolierende,feuerfeste Masse |
| US3477058A (en) * | 1968-02-01 | 1969-11-04 | Gen Electric | Magnesia insulated heating elements and methods of production |
| US4129774A (en) * | 1975-08-28 | 1978-12-12 | Hitachi Heating Appliances Co., Ltd. | Filling materials for heating elements |
| US4234786A (en) * | 1979-02-12 | 1980-11-18 | General Electric Company | Magnesia insulated heating elements and method of making the same |
| US4473654A (en) * | 1983-08-18 | 1984-09-25 | The J. E. Baker Company | Low temperature bonding of refractory aggregates and refractory products of improved cold strength |
| US4506251A (en) * | 1981-05-19 | 1985-03-19 | Matsushita Electric Industrial Co., Ltd. | Sheathed resistance heater |
| US6188051B1 (en) | 1999-06-01 | 2001-02-13 | Watlow Polymer Technologies | Method of manufacturing a sheathed electrical heater assembly |
| US6263158B1 (en) | 1999-05-11 | 2001-07-17 | Watlow Polymer Technologies | Fibrous supported polymer encapsulated electrical component |
| US6392206B1 (en) | 2000-04-07 | 2002-05-21 | Waltow Polymer Technologies | Modular heat exchanger |
| US6392208B1 (en) | 1999-08-06 | 2002-05-21 | Watlow Polymer Technologies | Electrofusing of thermoplastic heating elements and elements made thereby |
| US6433317B1 (en) | 2000-04-07 | 2002-08-13 | Watlow Polymer Technologies | Molded assembly with heating element captured therein |
| US6432344B1 (en) | 1994-12-29 | 2002-08-13 | Watlow Polymer Technology | Method of making an improved polymeric immersion heating element with skeletal support and optional heat transfer fins |
| US6516142B2 (en) | 2001-01-08 | 2003-02-04 | Watlow Polymer Technologies | Internal heating element for pipes and tubes |
| US6519835B1 (en) | 2000-08-18 | 2003-02-18 | Watlow Polymer Technologies | Method of formable thermoplastic laminate heated element assembly |
| US20050098684A1 (en) * | 2003-03-14 | 2005-05-12 | Watlow Polymer Technologies | Polymer-encapsulated heating elements for controlling the temperature of an aircraft compartment |
| US20120134655A1 (en) * | 2004-02-05 | 2012-05-31 | Paul Kam Ching Chan | Radiator apparatus |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2525441C3 (de) * | 1975-06-07 | 1981-04-16 | Dynamit Nobel Ag, 5210 Troisdorf | Elektrisch isolierende Füllung für einen elektrischen Rohrheizkörper |
| JPS52158576U (enrdf_load_stackoverflow) * | 1976-05-27 | 1977-12-01 | ||
| JPH01174302U (enrdf_load_stackoverflow) * | 1988-05-28 | 1989-12-12 |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2823134A (en) * | 1955-02-18 | 1958-02-11 | Armour Res Found | Densifying magnesia |
| US2864713A (en) * | 1955-09-09 | 1958-12-16 | Gen Electric Co Ltd | Ceramic dielectric compositions |
| US2957752A (en) * | 1960-10-25 | Process for increasing the density of | ||
| US2987689A (en) * | 1959-11-10 | 1961-06-06 | Thomas H Lennox | Resistance heating device |
| US3061752A (en) * | 1958-07-28 | 1962-10-30 | English Electric Valve Co Ltd | Television camera tubes |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE961737C (de) * | 1943-07-08 | 1957-04-11 | Siemens Ag | Pulverfoermiger oder koerniger, elektrisch isolierender Waermewerkstoff zum Einbetten elektrischer Heizleiter |
-
1962
- 1962-11-30 US US241378A patent/US3201738A/en not_active Expired - Lifetime
-
1963
- 1963-11-08 GB GB44199/63A patent/GB1059527A/en not_active Expired
- 1963-11-20 DE DE1963G0039206 patent/DE1465028B1/de active Pending
- 1963-11-25 JP JP6338763A patent/JPS4317150B1/ja active Pending
-
1969
- 1969-11-01 JP JP44087259A patent/JPS4817150B1/ja active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2957752A (en) * | 1960-10-25 | Process for increasing the density of | ||
| US2823134A (en) * | 1955-02-18 | 1958-02-11 | Armour Res Found | Densifying magnesia |
| US2864713A (en) * | 1955-09-09 | 1958-12-16 | Gen Electric Co Ltd | Ceramic dielectric compositions |
| US3061752A (en) * | 1958-07-28 | 1962-10-30 | English Electric Valve Co Ltd | Television camera tubes |
| US2987689A (en) * | 1959-11-10 | 1961-06-06 | Thomas H Lennox | Resistance heating device |
Cited By (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3369209A (en) * | 1964-02-07 | 1968-02-13 | Edwin Bjorn | Electric heating element |
| DE1902433A1 (de) * | 1968-02-01 | 1969-08-28 | Gen Electric | Elektrisch isolierende,feuerfeste Masse |
| US3477058A (en) * | 1968-02-01 | 1969-11-04 | Gen Electric | Magnesia insulated heating elements and methods of production |
| US4129774A (en) * | 1975-08-28 | 1978-12-12 | Hitachi Heating Appliances Co., Ltd. | Filling materials for heating elements |
| US4234786A (en) * | 1979-02-12 | 1980-11-18 | General Electric Company | Magnesia insulated heating elements and method of making the same |
| US4506251A (en) * | 1981-05-19 | 1985-03-19 | Matsushita Electric Industrial Co., Ltd. | Sheathed resistance heater |
| US4473654A (en) * | 1983-08-18 | 1984-09-25 | The J. E. Baker Company | Low temperature bonding of refractory aggregates and refractory products of improved cold strength |
| US6432344B1 (en) | 1994-12-29 | 2002-08-13 | Watlow Polymer Technology | Method of making an improved polymeric immersion heating element with skeletal support and optional heat transfer fins |
| US6263158B1 (en) | 1999-05-11 | 2001-07-17 | Watlow Polymer Technologies | Fibrous supported polymer encapsulated electrical component |
| US6434328B2 (en) | 1999-05-11 | 2002-08-13 | Watlow Polymer Technology | Fibrous supported polymer encapsulated electrical component |
| US6188051B1 (en) | 1999-06-01 | 2001-02-13 | Watlow Polymer Technologies | Method of manufacturing a sheathed electrical heater assembly |
| US6392208B1 (en) | 1999-08-06 | 2002-05-21 | Watlow Polymer Technologies | Electrofusing of thermoplastic heating elements and elements made thereby |
| US6433317B1 (en) | 2000-04-07 | 2002-08-13 | Watlow Polymer Technologies | Molded assembly with heating element captured therein |
| US6392206B1 (en) | 2000-04-07 | 2002-05-21 | Waltow Polymer Technologies | Modular heat exchanger |
| US6748646B2 (en) | 2000-04-07 | 2004-06-15 | Watlow Polymer Technologies | Method of manufacturing a molded heating element assembly |
| US6519835B1 (en) | 2000-08-18 | 2003-02-18 | Watlow Polymer Technologies | Method of formable thermoplastic laminate heated element assembly |
| US6541744B2 (en) | 2000-08-18 | 2003-04-01 | Watlow Polymer Technologies | Packaging having self-contained heater |
| US6516142B2 (en) | 2001-01-08 | 2003-02-04 | Watlow Polymer Technologies | Internal heating element for pipes and tubes |
| US6539171B2 (en) | 2001-01-08 | 2003-03-25 | Watlow Polymer Technologies | Flexible spirally shaped heating element |
| US6744978B2 (en) | 2001-01-08 | 2004-06-01 | Watlow Polymer Technologies | Small diameter low watt density immersion heating element |
| US20050098684A1 (en) * | 2003-03-14 | 2005-05-12 | Watlow Polymer Technologies | Polymer-encapsulated heating elements for controlling the temperature of an aircraft compartment |
| US20120134655A1 (en) * | 2004-02-05 | 2012-05-31 | Paul Kam Ching Chan | Radiator apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| GB1059527A (en) | 1967-02-22 |
| DE1465028B1 (de) | 1970-08-20 |
| JPS4317150B1 (enrdf_load_stackoverflow) | 1968-07-19 |
| JPS4817150B1 (enrdf_load_stackoverflow) | 1973-05-26 |
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