PlainPatent

CPC technology class · F23

F23L - Supplying AIR OR Non-combustible Liquids OR Gases TO Comb…

Supplying air or non-combustible liquids or gases to combustion apparatus in general  ; 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. 922 US utility patents granted 2015–2025, with the leading assignees and year-by-year filing trajectory.

922
US patents granted
F23
Parent CPC class
20
Active assignees
-12%
5-yr velocity

The verdict

Supplying AIR OR Non-combustible Liquids OR Gases TO Comb… ranks #470 of 670 CPC technology areas - 922 US patents granted since 2015, with filing down 12% over five years.

#470
of 670 CPC technology areas
922
US patents granted, 2015–2025
General Electric
leading assignee (33)
-12%
filing velocity, last 5 yrs
Top assignee: General Electric Company (33 patents)

CPC subclass F23L - SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL  ; 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 - covers 922 US utility patents granted between 2015 and 2025 according to USPTO PatentsView records, within the broader CPC class F23 (COMBUSTION APPARATUS; COMBUSTION PROCESSES). See our CPC classification guide for how the system works.

The competitive landscape in F23L is shaped by 20 distinct companies actively filing in this space. General Electric Company leads with 33 patents, followed by Noritz Corporation at 25 grants and 8 Rivers Capital, Llc at 21.

Filing activity in F23L is down 12% over the past five years versus 2015-2019, a relatively steady filing pace. All counts come directly from USPTO PatentsView and reflect US granted utility patents only.

Is F23L innovation accelerating?

US utility-patent grants per year in F23L, 2015–2025 - recent five years are down 12% versus 2015–2019.

406080100120 20152016201720182019202020212022202320242025 49

Who leads F23L?

The 12 most active assignees in SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL  ; 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 - wider bars mean more grants

patents

What this shows General Electric is the most active filer in F23L, holding 33 of the 922 patents in this class. Concentration at the top signals how contestable this technology area is for new entrants.

Source USPTO PatentsView, granted utility patents As of 2015–2025 grant years
View data table
Top patent holders in CPC subclass F23L
Rank Company Patents in F23L
#1 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude 31
#2 Noritz Corporation 25
#3 8 Rivers Capital, Llc 21
#4 Praxair Technology, Inc. 18
#5 Regal Beloit America, Inc. 16
#6 AIR Products AND Chemicals, Inc. 14
#7 Rinnai Corporation 13
#8 Kyungdong Navien Co., Ltd. 12
#9 Field Controls, Llc 11
#10 Rheem Manufacturing Company 9
#11 American Air Liquide, Inc. 9
#12 Clearsign Combustion Corporation 9
#13 Ener-core Power, Inc. 9
#14 Biochar Now, Llc 8
#15 GAS Technology Institute 7
#16 Membrane Technology And Research, Inc. 7
#17 ITEA S.p.a 7
#18 Taiyo Nippon Sanso Corporation 6
#19 Arvos Ljungstrom Llc 6
#20 HER Majesty THE Queen IN Right OF Canada AS Represented BY THE Minister OF Natual Resources 4

About This Class

CPC subclass F23L belongs to class F23.

922 patents were granted in this class between 2015 and 2025.

20 companies actively patent in this space.

Classification System

Cooperative Patent Classification (CPC) is a hierarchical patent classification system used by the USPTO and EPO.

← All Technology Classes Technology Rankings →

Footprint here vs. claim strategy

Each dot is a leading F23L assignee, placed by how many patents it holds in this class (horizontal) against its company-wide average claims per patent (vertical) - a read on whether the class is led by broad-but-shallow filers or focused deep-claim players.

Top 14 F23L assignees by class footprint. Bubble size = patents in F23L. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Top 14 F23L assignees by class footprint. Bubble size = patents in F23L. Source: USPTO PatentsView (claim depth is company-wide across all classes). Scatter plot of 14 data points (bubble-sized by third dimension). 010203040 010203040 Patents in F23L Avg claims / patent (company-wide) L'air Liquide Societe…Noritz8 Rivers CapitalPraxair TechnologyRegal Beloit AmericaAir Products And Chem…RinnaiKyungdong NavienField ControlsRheem ManufacturingAmerican Air LiquideClearsign CombustionEner-core PowerBiochar Now
Top 14 F23L assignees by class footprint. Bubble size = patents in F23L. Source: USPTO PatentsView (claim depth is company-wide across all classes).

Frequently Asked Questions

What is CPC class F23L?
CPC subclass F23L covers SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL  ; 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. It belongs to CPC class F23 (COMBUSTION APPARATUS; COMBUSTION PROCESSES), with 922 US utility patents granted since 2015.
How many patents have been filed in F23L?
922 US utility patents were granted in CPC subclass F23L between 2015 and 2025, based on USPTO PatentsView data.
Which company holds the most patents in F23L?
General Electric Company leads F23L with 33 patents, making it the most active assignee in this technology area.
How is patent data for F23L collected?
Patent data comes from USPTO PatentsView, a public research dataset maintained by the United States Patent and Trademark Office. It covers all US granted utility patents and assigns CPC codes based on the technology described in each patent.
What is the difference between CPC class and subclass?
A CPC class (e.g., F23) is a broad technology category. Subclasses like F23L provide finer granularity within that category. PlainPatent organizes data at the subclass level (4-character codes) for the most useful view of technology domains.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from USPTO PatentsView - official U.S. government patent data. See our methodology for computation details. Retrieved and formatted by PlainPatent Editorial

Every figure on PlainPatent is rendered directly from USPTO source data, no number is typed in by an editor. This page draws directly on USPTO source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.