US PATENT SUBCLASS 392 / 301
.~ Borehole type

Current as of: June, 1999
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392 /   HD   ELECTRIC RESISTANCE HEATING DEVICES

*  DD  HEATING DEVICES (CLASS 219 SUBCLASS 200) {11}
301.~ Borehole type {5}
302  DF  .~.~> With heat exchange fluid
303  DF  .~.~> With vapor generator
304  DF  .~.~> Heating element surrounding delivery pipe
305  DF  .~.~> Suspended by cable in well
306  DF  .~.~> Plural separate heating devices

DEFINITION

Classification: 392/301

Borehole type:

(under subclass 200) Subject matter under Class 219, ... wherein the heating device comprising an electrical resistance heating element is disclosed for use in an elongated hole in the earth.

(1) Note. The patents classified here are for electrical oil well heaters, per se. The combination of a heater and sufficient well structure is in Class 166.

SEE OR SEARCH CLASS

165, Heat Exchange,

45, for geos:graphical heat exchange.

166, Wells,

57+, and 272.1+ for well apparatus comprising a heater in the well and see subclass 60 for the line between Classes 166 and 219. See, also, (1) Note above.

175, Boring or Penetrating the Earth, 16+, for an electrical heating process or device for forming a hole in the earth by directly applying heat to fluidize or comminute the material forming the earth.

299, Mining or In Situ Disintegration of Hard Material,

3+, for mining by in situ conversion of solid to fluid and which includes heating means or steps and subclass 14 for process of directly applying heat.

405, Hydraulic and Earth Engineering,

131, for temperature modification or control of earthen formation by heating.

432, Heating,

62, for geos:graphic or structural installation.