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 [Search a list of Patent Appplications for class 373]   CLASS 373,INDUSTRIAL ELECTRIC HEATING FURNACES
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SECTION I - CLASS DEFINITION

GENERAL STATEMENT OF CLASS SUBJECT MATTER

Apparatus of this class is Characterized by the following: (1) Specialized to the use of electricity as the heat source; (2) heating within a chamber, enclosure, or other holding means; (3) melting of a charge (e.g., materials such as crushed ore or scrap), or preserving a melted charge in a molten state; and (4) manipulated, or operated in an industrial environment.

Processes of Operating the Apparatus of the above paragraph, per se, which do not recite a specific metallurgical treatment step.

Residual Industrial Electric Furnace Processes not elsewhere classifiable.

Industrial Electric Furnaces not elsewhere classifiable.

Apparatus used to simulate electric furnace operations and that is not elsewhere classifiable.

SUBCOMBINATIONS OF INDUSTRIAL ELECTRIC FURNACES PROVIDED FOR IN THIS CLASS

Any subcombination within the purview of the Statement of Class Subject Matter, above, and disclosed as having primary utility as part of an industrial electric furnace apparatus.

Other subcombinations (e.g., charge stirring apparatus) either claimed in conjunction with nominally disclosed industrial furnace apparatus, or disclosed as having primary utility in an industrial furnace apparatus except as enumerated by Exclusions, below.

COMBINATIONS OF OTHER APPARATUS WHICH INCLUDES APPARATUS OF THIS CLASS

Control Systems, or disparate device regulators not elsewhere classifiable are classified in this class.

Noninteractive combinations where the industrial electric furnace apparatus is more than nominally claimed, or where the combination is not elsewhere classifiable are classified in this class.

EXCLUSIONS

(1) An Industrial Electric Furnace which is a subcombination of a claimed encompassing system;

(2) Residential, or home heating furnace systems, or devices;

(3) Electrical Heating Apparatus with Furnacelike Enclosure, or holding means where: (a) there is no disclosure of utility relating to charge melting, or preserving in a molten state, or (b) any utility requiring melting is incorporated in a specific metallurgical treatment step (e.g., welding) which is elsewhere classifiable;

(4) Furnace apparatus powered by electricity whose primary principle of operation is unrelated to heating (e.g., electrolytic furnaces).

(5) Furnace apparatus of the charging and discharging type, wherein the furnace is only nominally recited. For example, a furnace apparatus of the aforementioned type only nominally reciting an electric furnace having a heating element will be found with the particular charging and discharging type.

SECTION II - REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:

65, Glass Manufacturing,   appropriate subclasses for nonelectric glass furnaces and furnace devices.
75, Specialized Metallurgical Processes, Compositions for use Therein, Consolidated Metal Powder Compositions, and Loose Metal Particulate Mixtures,   appropriate subclasses for processes of consolidating metalliferous material or extracting, refining, or melting metals and subclasses 10.1+ for electric reduction processes not directed merely to processes of operation or manipulation of the furnace.
110, Furnaces,   appropriate subclass, for furnaces of general utility, especially subclasses 235+ , for incinerators for the disposal of waster material, which incinerators may have structure to render a molten material, including metals, disposable.
117, Single-Crystal, Oriented-Crystal, and Epitaxy Growth Processes; Non-Coating Apparatus Therefor,   for non-coating apparatus for growing therein-defined single-crystal of all types of materials, including those having means for zone melting.
118, Coating Apparatus,   subclasses 58+ for coating apparatus combined with heating means for drying the coating, or for effecting a metallurgical treatment, e.g., annealing, of a coated article, or of an article which is about to be coated, and subclasses 726+ for details of crucible structures which contain coating material during vaporization.
126, Stoves and Furnaces,   appropriate subclasses for structural features peculiar to stoves and furnaces, see particularly subclass 343.5 for melting furnaces, or domestic utility.
159, Concentrating Evaporators,   appropriate subclasses for electrically heated furnaces for vaporizing liquid for the specific purpose of concentrating attendant solids.
164, Metal Founding,   appropriate subclasses for metal casting apparatus which may employ electric heating means.
175, Boring or Penetrating the Earth,   subclass 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.
196, Mineral Oils: Apparatus,   subclass 121 for vaporizing devices with electric heating means.
204, Chemistry: Electrical and Wave Energy,   appropriate subclasses for electrical furnaces and electrical processes for electrolysis, or for using electrical energy to cause chemical change as distinguished for its use for mere heating.
219, Electric Heating,   which is the generic class for heating electrically, as welding, metal heating, domestic heating, heating articles, or fluids.
222, Dispensing,   subclasses 591+ , especially subclasses 592+ for ladles, or tundishes used to dispense molten metals. Such dispensing vessels may include means to treat the molten metal where such a treatment is solely ancillary to and supportive of the dispensing operation, e.g., spout heaters to prevent clogging of the vessel outlet.
236, Automatic Temperature and Humidity Regulation,   subclass 15 for automatic temperature, or humidity control in combustion furnaces.
237, Heating Systems,   subclass 48 for furnace heating system ventilation.
241, Solid Material Comminution or Disintegration,   appropriate subclass, especially subclasses 65+ , for comminuting, or disintegrating means, per se, or combined with heating means which do not effect a change in the chemical nature of the material being treated.
250, Radiant Energy,   subclass 251 for molecular, or atomic beam devices for producing and propagating an unidirectional stream of neutral molecules, or atoms through a vacuum, usually at thermal velocity, subclasses 324+ for methods and apparatus to irradiate materials by corona radiation, subclass 423 for methods and apparatus to generate ions, subclasses 428+ for methods and apparatus to support, contain, or transfer fluent material with, or without an irradiating source, subclasses 453.1+ for methods and apparatus including supports for objects to be irradiated with, or without an irradiating source, subclasses 458.1+ for methods and apparatus to irradiate luminophors, subclass 492.1+ for methods and apparatus to irradiate objects, or materials generally, and subclasses 472.1+ for invisible radiation generation and sources, particularly subclasses 493.1+ for neutron generators.
264, Plastic and Nonmetallic Article Shaping or Treating: Processes,   subclass 30 , for methods of forming, or repairing furnace linings by shaping, e.g., molding, fluent refractory material.
266, Metallurgical Apparatus,   for electric, or nonelectric features of metallurgical furnaces not limited to characteristics of an electric furnace (except electric heating or pouring spout, or material at discharge area when only disclosed in an electric furnace).
313, Electric Lamp and Discharge Devices,   subclass 327 for self-baking electrode structures, per se.
315, Electric Lamp and Discharge Devices: Systems,   appropriate subclasses for systems for supplying electric current to arc furnaces provided that the arc furnace is only nominally disclosed.
323, Electricity: Power Supply or Regulation Systems,   for electrical power supply, or regulating systems with nominally disclosed electric furnace devices.
327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems,   subclasses 365+ for miscellaneous gating circuits, subclasses 509+ for miscellaneous externally effected circuits, subclasses 518+ for miscellaneous control circuits, and subclasses 538+ for miscellaneous bias circuits with regulating.
336, Inductor Devices,   for inductive devices, per se.
376, Induced Nuclear Reactions: Processes, Systems, and Elements,   subclass 107 , 121+ and 144 for means utilizing an electrically controlled plasma to produce a thermonuclear reaction.
414, Material or Article Handling,   subclasses 147+ for furnace charging apparatus, or for furnace chargers combined with that specific furnace structure which is solely for facilitating the movement of the material into the furnace.
432, Heating,   appropriate subclass, for heating apparatus of general utility.
501, Compositions: Ceramic,   appropriate subclasses for furnace lining compositions.

SECTION III - GLOSSARY

ARC

A prolonged electrical discharge, or series of prolonged discharges between two electrodes, or between an electrode and a current carrying material.

CHANNEL

A hollow loop, or ring which will contain material to be heated, and which permits the insertion of a core of iron to improve the coupling between a primary coil and a secondary in the loop, or ring.

CHARGE

The material heated by the furnace.

CHARGING

The function of supplying a charge to a furnace.

CRUCIBLE

A component of the furnace which holds, or otherwise contains the charge.

DISCHARGING

The function of removing a charge from a furnace.

ELECTRODE

An electrical conducting element that emits, or collects electrons, or ions, or controls their movement by means of an electric field on it.

ELECTRON BEAM

A narrow stream of electrons moving in the same direction under the influence of an electric, or magnetic field.

ELECTROSLAG DEVICE

Apparatus enabling one, or more electrodes to be immersed in a slag layer which floats on top of the melt.

FILAMENT

A slender thread of material.

FURNACE

A chamber, enclosure, or other holding means for heating materials therein.

GLOW DISCHARGE

The phenomenon of electrical conduction in gasses shown by a slight luminosity, without great hissing, or noise, and without appreciable heating, or volatilization of the electrode, when the electrostatic pressure exceeds a certain value.

HEARTH

The part of the furnace upon which the charge is placed and melted down, or refined.

INDUCTION HEATING

The method of producing heat in a charge by placing it in a electromagnetic relationship with an inducing winding, the charge forming the secondary.

INGOT

The casting obtained when molten metal is poured into a mold with the expectation that it be further processed.

PLASMA

A wholly, or partially ionized gas in which the positive ions and the negative electrons are roughly equal in number.

ROOF

A cover, or lid for the furnace.

SLAG

A more, or less completely fused and vitrified material separated during the reduction of a metal from its ore which generally floats on top of the molten metal during the heat reduction processes found in this class.

ZONE MELTING

A process where a selected area of a charge is heated in liquification.

SUBCLASSES

[List of Patents for class 373 subclass 1]    1PLURAL DIVERSE HEATING MEANS:
 This subclass is indented under the class definition.  Subject matter including plural, different in kind, or type heating elements.
(1) Note. Usually either the plural heating elements operate on the same charge, or one of the heating elements operates as a substitute for the other.

SEE OR SEARCH CLASS:

432, Heating,   subclass 94 for heating apparatus having (a) two distinctly different types of heat generators, (b) a heat generator and a source of heat that is not a generator, or (c) a combustion type heat generating means using two different fuels.
  
[List of Patents for class 373 subclass 2]    2Arc:
 This subclass is indented under subclass 1.  Subject matter wherein one of the heating elements is an electric arc between two electrodes, or between an electrode and a current carrying material (e.g., the charge material).

SEE OR SEARCH THIS CLASS, SUBCLASS:

9,for arc furnaces with environmental control devices.
60,for arc furnace devices, per se.

SEE OR SEARCH CLASS:

164, Metal Founding,   subclass 514 for electric arc heating apparatus used for metal casting.
219, Electric Heating,   subclasses 121.11+ for arc metal heating, per se.
  
[List of Patents for class 373 subclass 3]    3With resistance:
 This subclass is indented under subclass 2.  Subject matter including means to develop heat by the passage of current through a material, or device having the property of electrical resistance.

SEE OR SEARCH THIS CLASS, SUBCLASS:

5+,for resistance furnaces combined with heating elements other than an electrical arc.
109+,for resistance furnace details, per se.

SEE OR SEARCH CLASS:

219, Electric Heating,   subclasses 200+ for electric resistance heating, per se.
  
[List of Patents for class 373 subclass 4]    4With induction:
 This subclass is indented under subclass 2.  Subject matter including means to produce heat in a charge by placing it in an electromagnetic relationship with an inducing winding, the charge forming the secondary.

SEE OR SEARCH THIS CLASS, SUBCLASS:

6,for induction heating elements combined with resistance furnaces.
7,for induction furnaces combined with heating elements other than an electrical arc, or resistance element.
138+,for induction furnace details, per se.

SEE OR SEARCH CLASS:

164, Metal Founding,   subclass 513 for inductive heating apparatus used for metal casting.
219, Electric Heating,   subclasses 600+ for inductive heating, subclasses 678+ for microwave heating, and subclasses 764+ for capacitive dielectric heating.
  
[List of Patents for class 373 subclass 5]    5Resistance:
 This subclass is indented under subclass 1.  Subject matter wherein one of the heating elements is a means to develop heat by the passage of current through a material, or device having the property of electrical resistance.

SEE OR SEARCH THIS CLASS, SUBCLASS:

3,for resistance heating elements combined with arc furnaces.
109+,for resistance furnace details, per se.

SEE OR SEARCH CLASS:

219, Electric Heating,   subclasses 200+ for electric resistance heating, per se.
  
[List of Patents for class 373 subclass 6]    6With induction:
 This subclass is indented under subclass 5.  Subject matter including means to produce heat in a charge by placing it in an electromagnetic relationship with an inducing winding, the charge forming the secondary.

SEE OR SEARCH THIS CLASS, SUBCLASS:

4,for inductance heating elements combined with are furnaces.
7,for induction furnaces combined with heating elements other than an electrical arc, or resistance element.
138+,for induction furnace details, per se.

SEE OR SEARCH CLASS:

164, Metal Founding,   subclass 513 for inductive heating apparatus used for metal casting.
219, Electric Heating,   subclasses 600+ for inductive heating, subclasses 678+ for microwave heating, and subclasses 764+ for capacitive dielectric heating.
  
[List of Patents for class 373 subclass 7]    7Induction:
 This subclass is indented under subclass 1.  Subject matter including means to produce heat in a charge by placing it in an electromagnetic relationship with an inducing winding, the charge forming the secondary.

SEE OR SEARCH THIS CLASS, SUBCLASS:

4,for inductance heating elements combined with arc furnaces.
6,for inductance heating elements combined with resistance furnaces.
138+,for induction furnace details, per se.

SEE OR SEARCH CLASS:

164, Metal Founding,   subclass 513 for inductive heating apparatus used for metal casting.
219, Electric Heating,   subclasses 600+ for inductive heating, subclasses 678+ for microwave heating, and subclasses 764+ for capacitive dielectric heating.
  
[List of Patents for class 373 subclass 8]    8ENVIRONMENTAL CONTROL:
 This subclass is indented under the class definition.  Subject matter including means to withdraw furnace gases, or to trap dust and fumes escaping from the furnace while in operation.

SEE OR SEARCH CLASS:

266, Metallurgical Apparatus,   subclasses 144+ for means treating, or handling gases exhausted by treating means.
  
[List of Patents for class 373 subclass 9]    9Arc furnace:
 This subclass is indented under subclass 8.  Subject mater wherein, the furnace heating element is an electric arc between two electrodes, or between an electrode and a current carrying material (e.g., the charge material).

SEE OR SEARCH THIS CLASS, SUBCLASS:

2+,for arc furnaces combined with other heating means.
60+,for arc furnace devices, per se.
  
[List of Patents for class 373 subclass 10]    10ELECTRON BEAM FURNACE DEVICE:
 This subclass is indented under the class definition.  Subject matter wherein heat is generated to melt charge material by the effects of the impingement, of a directed beam, of accelerated electrons on the charge.

SEE OR SEARCH CLASS:

75, Specialized Metallurgical Processes, Compositions for Use Therein, Consolidated Metal Powder Compositions, and Loose Metal Particulate Mixtures,   subclasses 10.19+ for the production of metal or the treatment of molten metal using a wholly or partially charged mixture of gaseous ions and electrons (i.e. plasma) as the source of thermal energy.
219, Electric Heating,   subclasses 121.13+ for welding, machining and general heating applications utilizing electron beams, search here also for electron guns, or emitters, per se.
250, Radiant Energy,   subclass 251 for molecular, or atomic beam devices for producing and propagating a unidirectional stream of neutral molecules, or atoms through a vacuum, usually at thermal velocity, subclasses 324+ for methods and apparatus to irradiate materials by corona radiation, subclass 423 for methods and apparatus to generate ions, subclasses 428+ for methods and apparatus to support, contain, or transfer fluent material with, or without an irradiating source, subclass 453.11 for methods and apparatus including supports for objects to be irradiated with, or without an irradiating source, subclass 458.1 for the methods and apparatus to irradiate luminophors, subclasses 492.1+ for methods and apparatus to irradiate objects, or materials generally, and subclass 493.1 for invisible radiation generation and sources, particularly subclasses 493.1+ for neutron generators.
  
[List of Patents for class 373 subclass 11]    11Vaporizing furnace:
 This subclass is indented under subclass 10.  Subject matter wherein the charge is heated by the electron beam to a gaseous state.
(1) Note. Generally crucibles are fully charged, then moved into an area to be struck by the electron beam and then out from under the beam when the charge is substantially vaporized.

SEE OR SEARCH THIS CLASS, SUBCLASS:

33+,for glass furnace charging devices.
46+,and 42, for electroslag remelting furnace start up charging and alloying devices respectively.
63,for indirect arc furnaces where the charge is fed into the space between the electrodes.
67+,for arc furnace ingot remelting where furnace electrodes constitute the charge material.
72+,for arc furnace crucible details.
79+,for arc furnace charging, per se.
115,for resistance furnace charging, per se.
142+,for induction furnace charging, per se.

SEE OR SEARCH CLASS:

110, Furnaces,   subclasses 267+ and 327+ for furnace solid fuel feeders and subclasses 101+ for furnace fuel feeders, per se.
118, Coating Apparatus,   subclasses 726+ for details of crucible structures which contain coating material during vaporization.
219, Electric Heating,   subclasses 420+ for electric heating devices combined with nominally disclosed crucible, or furnace-type containers.
266, Metallurgical Apparatus,   subclasses 200+ for means to melt, or vaporize metal, or to treat liquified metal.
392, Electric Resistance Heating Devices,   appropriate subclasses for electric heating apparatus.
422, Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing,   subclass 244 for serially disposed vaporizing heating means with solid material deposition means maintained at a temperature lower than said heating means.
431, Combustion,   subclass 208 for a fuel burner having an electrically heated fuel vaporizer.
  
[List of Patents for class 373 subclass 12]    12Power supply and control circuit:
 This subclass is indented under subclass 11.  Subject matter including means to regulate and power the operation of the vaporizing furnace.

SEE OR SEARCH THIS CLASS, SUBCLASS:

25,for plasma furnaces control systems.
40,for glass furnace electrical system regulation.
49+,for electroslag remelting furnaces with power supply control.
70,and 104+, for arc furnace power regulation.
135,for resistance furnace control, per se.
148,for induction furnace power supply regulation.
  
[List of Patents for class 373 subclass 13]    13Gun assembly:
 This subclass is indented under subclass 11.  Subject matter including the component structure of the means which emits the electron beam.

SEE OR SEARCH THIS CLASS, SUBCLASS:

18,for plasma furnace plasma gun details.

SEE OR SEARCH CLASS:

219, Electric Heating,   subclass 121.27 for electron gun assembly in electron beam heating devices.
  
[List of Patents for class 373 subclass 14]    14With deflection control:
 This subclass is indented under subclass 13.  Subject matter including means to regulate the path of the electron beam.
  
[List of Patents for class 373 subclass 15]    15Ingot remelting:
 This subclass is indented under subclass 10.  Subject matter wherein a previously melted and subsequently solidified ingot charge is remelted by the furnace.

SEE OR SEARCH THIS CLASS, SUBCLASS:

21+,for plasma furnace ingot remelting.
67+,for arc furnace ingot remelting.

SEE OR SEARCH CLASS:

266, Metallurgical Apparatus,   subclasses 200+ for means to melt, or vaporize metal, per se.
432, Heating,   appropriate subclass for melting furnaces of general utility.
  
[List of Patents for class 373 subclass 16]    16With plural beam devices:
 This subclass is indented under subclass 10.  Subject matter wherein the furnace has more than one electron beam gun.
  
[List of Patents for class 373 subclass 17]    17Zone melting:
 This subclass is indented under subclass 10.  Subject matter wherein a small area, or zone of the charge is liquified by the electron beam.

SEE OR SEARCH THIS CLASS, SUBCLASS:

139,for zone melting utilizing induction heating.

SEE OR SEARCH CLASS:

75, Specialized Metallurgical Processes, Compositions for use Therein, Consolidated Metal Powder Compositions, and Loose Metal Particulate Mixtures,   subclass 10.11 for processes of zone melting of metal.
117, Single-Crystal, Oriented-Crystal, and Epitaxy Growth Processes; Non-Coating Apparatus Therefor,   subclasses 37+ for processes for growing therein-defined single-crystal of all types of materials, including by zone melting, and subclasses 219+ for non-coating apparatus for growing therein-defined single-crystal of all types of materials, including by zone melting means.
422, Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing,   subclass 250.1 for non-coating crystallizing apparatus which includes means for zone melting, not including means for chemical reaction, and not provided for elsewhere.
  
[List of Patents for class 373 subclass 18]    18PLASMA FURNACE DEVICE:
 This subclass is indented under the class definition.  Subject matter including a plasma generating means as the heat source to melt, or otherwise treat the material within the furnace device.
(1) Note. A plasma flame is generated when an ionizable gas is forced through an electrical field.
(2) Note. Plasmatrons are also referred to as "arc torches," "plasma guns", etc.

SEE OR SEARCH THIS CLASS, SUBCLASS:

13+,for electron beam vaporizing furnace gun assembly details.
24,for direct plasma furnaces with side wall mounted plasmatrons.

SEE OR SEARCH CLASS:

313, Electric Lamp and Discharge Devices,   subclasses 231.31+ for fluent material supplied plasma devices.
315, Electric Lamp and Discharge Devices: Systems,   subclasses 111.21+ for plasma generating systems.
  
[List of Patents for class 373 subclass 19]    19Indirect heating:
 This subclass is indented under subclass 18.  Subject matter wherein the material being heated is heated principally by heat radiation from the plasma flame, without direct contact with the flame.

SEE OR SEARCH THIS CLASS, SUBCLASS:

61+,for arc furnace indirect heating details.
  
[List of Patents for class 373 subclass 20]    20Rotary furnace:
 This subclass is indented under subclass 19.  Subject matter wherein the furnace is rotated, generally about its longitudinal axis.

SEE OR SEARCH CLASS:

432, Heating,   subclasses 103+ for tumbler- type rotary drum furnaces, per se.
  
[List of Patents for class 373 subclass 21]    21Remelting furnace (i.e., ingot remelting):
 This subclass is indented under subclass 18.  Subject matter wherein the plasma furnace remelts ingots produced from a previous melting/costing process.

SEE OR SEARCH THIS CLASS, SUBCLASS:

15,for electron beam furnace ingot remelting apparatus.
42+,for electroslag remelting devices.
67+,for arc furnace ingot remelting apparatus.
  
[List of Patents for class 373 subclass 22]    22Direct furnace (i.e., plasma flame impinges on the melt):
 This subclass is indented under subclass 18.  Subject matter wherein the plasma flame is in contact with the material being melted.

SEE OR SEARCH CLASS:

204, Chemistry: Electrical and Wave Energy,   subclasses 164+ for chemical processes employing a plasma.
376, Induced Nuclear Reactions: Processes, Systems, and Elements,   subclasses 100+ for means utilizing plasma to produce a thermonuclear reaction.
  
[List of Patents for class 373 subclass 23]    23Expanded arc column:
 This subclass is indented under subclass 22.  Subject matter wherein the plasma flame expands, usually in a conical shape, as it extends away from the plasmatron.
  
[List of Patents for class 373 subclass 24]    24Sidewall mounted plasmatron:
 This subclass is indented under subclass 22.  Subject matter wherein the plasmatron means extends through and is supported by the furnace sidewall.

SEE OR SEARCH THIS CLASS, SUBCLASS:

18,for plasma furnace plasmatrons, per se.
  
[List of Patents for class 373 subclass 25]    25Control system:
 This subclass is indented under subclass 22.  Subject matter including means to regulate the operation of the furnace.

SEE OR SEARCH THIS CLASS, SUBCLASS:

25,for control systems in plasma remelting furnaces.
40,for electrical system regulation of glass furnaces.
49+,for power supply control in electroslag remelting furnaces.
70,77 and 104+, for control, or regulation of arc furnace devices.
110+,and 135, for control, or regulation of resistance furnace devices.
140+,148, and 149+, for control, or regulation of induction furnace devices.
  
[List of Patents for class 373 subclass 26]    26GLOW DISCHARGE FURNACE DEVICE:
 This subclass is indented under the class definition.  Subject matter wherein the heat is produced from a glow discharge generated within the furnace.

SEE OR SEARCH CLASS:

313, Electric Lamp and Discharge Devices,   subclass 615 , 618 and 619 for glow- type discharge devices, per se.
  
[List of Patents for class 373 subclass 27]    27GLASS FURNACE DEVICE:
 This subclass is indented under the class definition.  Subject matter specifically adapted for melting, or treating glass or silica.

SEE OR SEARCH THIS CLASS, SUBCLASS:

109+,for resistance furnaces, per se.

SEE OR SEARCH CLASS:

65, Glass Manufacturing,   subclass 335 for nonelectric glass furnaces with furnace charging means; subclass 347 for nonelectric furnaces having a structurally defined delivery or fining zone, and see the search notes thereunder.
  
[List of Patents for class 373 subclass 28]    28Filament discharge (i.e., bushing):
 This subclass is indented under subclass 27.  Subject matter wherein the glass is melting in a bushing from which the molten glass is discharged as filaments, the bushing being heated by passing a current therethrough.

SEE OR SEARCH CLASS:

65, Glass Manufacturing,   subclasses 384+ for glass fiber and filament making apparatus, especially subclasses 493+ for means for forming bushings with designated compositions; subclasses 496+ for means for forming specified bushing tip or glass feeder structure.
  
[List of Patents for class 373 subclass 29]    29Joule effect heating:
 This subclass is indented under subclass 27.  Subject matter wherein the glass is melted, or maintained in a molten condition by passing an electric current therethrough between at least two electrodes.

SEE OR SEARCH CLASS:

266, Metallurgical Apparatus,   subclass 104 for treating a continuum of work by joule effect heating means.
  
[List of Patents for class 373 subclass 30]    30Furnace body detail:
 This subclass is indented under subclass 29.  Subject matter pertaining to the furnace body or tank for holding the molten glass.

SEE OR SEARCH THIS CLASS, SUBCLASS:

44,for details of electroslag remelting furnace bodies.
71+,for arc furnace body details.
156,and 163, for induction furnace crucible details.
  
[List of Patents for class 373 subclass 31]    31Multichamber:
 This subclass is indented under subclass 30.  Furnaces which are composed of at least two discrete interconnected sections.
(1) Note. For example, melting and refining section, or melting and delivery zones.

SEE OR SEARCH THIS CLASS, SUBCLASS:

78,for plural arc furnace units operating sequentially on the same charge.
80,for arc furnace charge preheating.
144,for induction furnaces with plural heating elements operating sequentially on a charge.
  
[List of Patents for class 373 subclass 32]    32With heating between chambers:
 This subclass is indented under subclass 31.  Subject matter including heating means mounted in the passageway between the plural furnace sections, or including furnaces where the heating current flows between electrodes mounted one in each furnace section.
  
[List of Patents for class 373 subclass 33]    33Charging or discharging:
 This subclass is indented under subclass 29.  Subject matter including means to supply, or remove material to be heated, to or from the furnace.

SEE OR SEARCH THIS CLASS, SUBCLASS:

11,for electron beam furnace charging means.
42+,and 46+, for electroslag remelting furnace start up charging and alloying devices respectively.
63,for indirect arc furnaces where the charge is fed into the space between the electrodes.
67+,for arc furnace ingot remelting where furnace electrodes constitute the charge material.
79+,for arc furnace charging/discharging, per se.
115,for resistance furnace charging/discharging, per se.
142+,for induction furnace charging/discharging, per se.

SEE OR SEARCH CLASS:

110, Furnaces,   subclasses 267+ and 327+ for furnace solid fuel feeders and subclasses 101+ for furnace fuel feeders, per se.
222, Dispensing,   subclasses 591+ for molten metal dispensing.
266, Metallurgical Apparatus,   subclasses 176+ for means to supply a charge to a heating means.
414, Material or Article Handling,   subclasses 147+ for charging a chamber utilized for a heating function.
  
[List of Patents for class 373 subclass 34]    34Including batch preheating:
 This subclass is indented under subclas