| F | SK | MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING |
| F27 | KL | FURNACES; KILNS; OVENS; RETORTS (specially adapted for a purpose covered by a single other class and specifically mentioned in that class, see the class in question, e.g. bakery ovens A21B , glass melting furnaces C03B , coke or gas-making apparatus C10B , C10J , apparatus for cracking hydrocarbons C10G , blast furnaces C21B , converters for making steel C21C , furnaces for heat treatment of metal C21D; furnaces for electroslag or arc remelting of metals C22B 9/00; enamelling ovens C23D; combustion apparatus F23; electric heating H05B) [4] |
| F27D | UKL | DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE (combustion apparatus F23) |
| F27D 1/00 | HGR | Casings; Linings; Walls; Roofs (refractory materials C04B; firebridges for combustion chambers F23M 3/00) |
| F27D 1/02 | UGR1 | |
| F27D 1/04 | UGR1 | | . | characterised by the form of the bricks or blocks used |
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| F27D 1/06 | UGR2 | | . . | Composite bricks or blocks |
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| F27D 1/08 | UGR3 | | . . . | Bricks or blocks with internal reinforcement or metal backing |
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| F27D 1/10 | UGR1 | | . | Monolithic linings; Supports therefor |
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| F27D 1/12 | UGR1 | | . | incorporating cooling arrangements (constructions of tube assemblies in general F28) |
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| F27D 1/14 | UGR1 | | . | Supports for linings (F27D 1/10 takes precedence) |
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| F27D 1/16 | UGR1 | | . | Making or repairing linings |
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| F27D 1/18 | UGR1 | | . | Door frames; Doors, lids, removable covers |
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| F27D 3/00 | HGR | Charging; Discharging; Manipulation of charge (conveying systems characterised by their application for specified purposes not otherwise provided for B65G 49/00; moving charge through a furnace F27B 9/14) |
| F27D 3/02 | UGR1 | | . | Skids or tracks for heavy objects |
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| F27D 3/04 | UGR1 | |
| F27D 3/06 | UGR1 | | . | Charging or discharging machines on travelling carriages |
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| F27D 3/08 | UGR1 | | . | Screw feeders; Screw dischargers |
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| F27D 3/10 | UGR1 | | . | Charging directly from hoppers or shoots |
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| F27D 3/12 | UGR1 | | . | Travelling or movable supports or containers for the charge |
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| F27D 3/14 | UGR1 | | . | Charging or discharging liquid or molten material |
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| F27D 3/15 | UGR1 | | . | Tapping equipment; Equipment for removing slag |
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| F27D 3/16 | UGR1 | | . | Introducing a fluid jet or current into the charge (F27D 3/18 takes precedence) [3] |
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| F27D 3/18 | UGR1 | | . | Charging particulate material using a fluid carrier [3] |
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| F27D 5/00 | HGR | Supports, screens, or the like for the charge within the furnace (travelling or movable supports F27D 3/12) |
| F27D 7/00 | HGR | Forming, maintaining, or circulating atmospheres in heating chambers |
| F27D 7/02 | UGR1 | | . | Supplying steam, vapour, gases, or liquids |
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| F27D 7/04 | UGR1 | | . | Circulating atmospheres by mechanical means |
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| F27D 7/06 | UGR1 | | . | Forming or maintaining special atmospheres or vacuum within heating chambers (F27D 7/02 takes precedence) |
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| F27D 9/00 | HGR | Cooling of furnaces or of charges therein (F27D 1/00 , F27D 3/00 take precedence) |
| F27D 11/00 | HGR | Arrangement of elements for electric heating in or on furnaces (electric heating per se H05B) |
| F27D 11/02 | UGR1 | | . | Ohmic resistance heating |
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| F27D 11/04 | UGR2 | | . . | with direct passage of current through the material being heated |
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| F27D 11/06 | UGR1 | | . | Induction heating, i.e. in which the material being heated, or its container or elements embodied therein, form the secondary of a transformer |
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| F27D 11/08 | UGR1 | | . | Heating by electric discharge, e.g. arc discharge |
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| F27D 11/10 | UGR2 | | . . | Disposition of electrodes (automatic control of temperature G05D 23/00; electric discharge apparatus H01T; arrangements for feeding or guiding electrodes H05B 7/10; automatic control of power by positioning of electrodes H05B 7/144) [3] |
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| F27D 11/12 | UGR1 | | . | with electromagnetic fields acting directly on the material being heated |
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| F27D 13/00 | HGR | Apparatus for preheating charges; Arrangements for preheating charges |
| F27D 15/00 | HGR | Handling or treating discharged material; Supports or receiving chambers therefor |
| F27D 15/02 | UGR1 | |
| F27D 17/00 | HGR | Arrangement for using waste heat (heat-exchangers per se F28); Arrangement for using, or disposing of, waste gases (removing fumes in general B08B 15/00) |
| F27D 19/00 | HGR | Arrangement of controlling devices |
| F27D 21/00 | HGR | Arrangement of monitoring devices; Arrangements of safety devices |
| F27D 21/02 | UGR1 | | . | Observation or illuminating devices |
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| F27D 21/04 | UGR1 | | . | Arrangements of indicators or alarms |
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| F27D 23/00 | HGR | Details or accessories not covered by any preceding group |
| F27D 23/02 | UGR1 | | . | Devices for removing incrustations |
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| F27D 23/04 | UGR1 | | . | Stirring devices for molten material (mixing in general B01F) [3] |
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