US3621204A
Expired / Lapsed
US
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Electrical heating element with fused magnesia insulation
Assignee: Dynamit Nobel AG
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Filing: 1970-04-29
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Granted: 1971-11-16
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Expires: 1990-04-29
Abstract
Abstract An electrical heating element comprising a resistance wire in a metal tubular jacket insulated therefrom with a fused granular magnesia is improved from the standpoint of electrical leakage or loss by admixing with the magnesia a small amount of a sintered and finely divided magnesium silicate or magnesium oxide having a particle size substantially completely under 10 microns.
Inventors
- 👤 Manfred Neidhardt
- 👤 Joseph Schneider
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:55
CPC Classifications
H; H05; H05B; H05B3/00; H05B3/40; H05B3/42; H05B3/48; H01; H01B; H01B3/00; H01B3/02; H01B3/025
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
50 words
The process of claim 1 wherein said material is a magnesium silicate prepared by sintering the same above 1,100* C. followed by the crushing of the resulting sintered block to a grain size under 0.37 mm., and the quantity added being in the range of 0.05 to 6 weight percent.
Claim 2
Dependent Claim
31 words
in the range of 0.05 to 20 weight percent of sintered and finely divided magnesium silicate or magnesium oxide, the grains thereof predominately having a size of less than 10 microns.
Claim 3
Dependent Claim
56 words
The process of claim 1 wherein said material is a magnesium oxide prepared from magnesia of a grain size under 5 microns by sintering at 1,500*-2,000* C., followed by crushing of the resulting sintered block to a grain size under 0.37 mm. and the quantity added being in the range of 3 to 20 weight percent.
Claim 4
Dependent Claim
45 words
A granulated magnesia composition adapted as insulation for electrical heating elements, consisting essentially of magnesium oxide powder and added to said powder a pulverized sintered magnesium silicate or magnesium oxide, the grains of which consist virtually entirely of individual crystals under 10 microns in size.
Claim 5
Dependent Claim
37 words
The magnesia composition of claim 4 wherein when the sintered material added is magnesium silicate the amount is 0.05 to 6 weight percent and when it is magnesium oxide, the amount is 3 to 20 weight percent.
Claim 6
Dependent Claim
30 words
In an electrical heating element comprising a resistance wire in a conductive tubular jacket with a fused granular insulation therebetween, the improvement comprising using as said insulation a mixture of
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-15 | 1975-05-17 | 1975-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-15 | 1979-05-17 | 1979-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-15 | 1983-05-17 | 1983-11-16 | $7700.00 | Window Closed / Lapsed |