F23L SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ( firebridges with means for feeding air or steam F23M3/04; baffles or shields with air supply passages F23M9/04); VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS ; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
Description
F23L encompasses equipment and systems for managing air supply and draught in combustion apparatus, including specialized valves, dampers, and draught-inducing devices. It covers delivery mechanisms for air and non-combustible fluids to furnaces, boilers, and similar combustion systems, as well as physical components like chimney tops and flue terminals that regulate gas flow and prevent downdrafts. This classification excludes fuel supply systems (covered elsewhere in F23) and focuses specifically on the oxidant/air side of combustion control and ventilation management.
Filing statistics
CPC subclass F23L recorded 12,448 patent applications worldwide between 2013 and 2023. Annual filings grew from 880 in 2013 to 1,048 in 2023 (+19%), peaking at 1,464 applications in 2020. The most active applicants in class F23 are GE (GENERAL ELECTRIC COMPANY) (2,581 applications), UNITED TECHNOLOGIES CORPORATION (UTC) (1,180 applications) and SIEMENS (1,157 applications).
Source: EPO PATSTAT, worldwide filings
12 direct subcodes
Child Classifications
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- F23L 1/00 Passages or apertures for delivering primary air for combustion (baffles or deflectors in air inlets F23M9/02)
- F23L 11/00 Arrangements of valves or dampers after the fire
- F23L 13/00 Construction of valves or dampers for controlling air supply or draught
- F23L 15/00 Heating of air supplied for combustion
- F23L 17/00 Inducing draught; Tops for chimneys or ventilating shafts; Terminals for flues
- F23L 2700/00 Installations for increasing draught in chimneys; Specific draught control devices for locomotives
- F23L 2900/00 Special arrangements for supplying or treating air or oxidant for combustion; Injecting inert gas, water or steam into the combustion chamber
- F23L 3/00 Arrangements of valves or dampers before the fire
- F23L 5/00 Blast-producing apparatus before the fire
- F23L 7/00 Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
- F23L 9/00 Passages or apertures for delivering secondary air for completing combustion of fuel (baffles or deflectors in air inlets F23M9/02)
- F23L 99/00 Subject matter not provided for in other groups of this subclass
Top Applicants
Top 10 applicants by patent filingsfor class F23, 2013–2023, worldwide · Source: EPO PATSTAT
- GE (GENERAL ELECTRIC COMPANY) US 2,581
- UNITED TECHNOLOGIES CORPORATION (UTC) US 1,180
- SIEMENS DE 1,157
- GE (GENERAL ELECTRIC COMPANY) 994
- XIAN THERMAL POWER RESEARCH INSTITUTE COMPANY 769
- MITSUBISHI HEAVY INDUSTRIES JP 701
- MITSUBISHI HITACHI POWER SYSTEMS JP 695
- RAYTHEON TECHNOLOGIES CORPORATION US 587
- NINGBO FOTILE KITCHENWARE COMPANY 543
- GENERAL ELECTRIC TECHNOLOGY CH 490