Prosecution Insights
Last updated: April 18, 2026
Application No. 18/367,521

SYSTEM OF PREVENTING BACKFLASH IN PRE-MIXED HYDROGEN BURNER AND METHOD THEREOF

Non-Final OA §102§103§112
Filed
Sep 13, 2023
Examiner
SHIRSAT, VIVEK K
Art Unit
3762
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Kia Corporation
OA Round
1 (Non-Final)
74%
Grant Probability
Favorable
1-2
OA Rounds
3y 0m
To Grant
99%
With Interview

Examiner Intelligence

Grants 74% — above average
74%
Career Allow Rate
781 granted / 1061 resolved
+3.6% vs TC avg
Strong +28% interview lift
Without
With
+28.5%
Interview Lift
resolved cases with interview
Typical timeline
3y 0m
Avg Prosecution
60 currently pending
Career history
1121
Total Applications
across all art units

Statute-Specific Performance

§101
0.4%
-39.6% vs TC avg
§103
45.7%
+5.7% vs TC avg
§102
25.2%
-14.8% vs TC avg
§112
23.3%
-16.7% vs TC avg
Black line = Tech Center average estimate • Based on career data from 1061 resolved cases

Office Action

§102 §103 §112
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Claim Objections Claim 14 is objected to because of the following informalities: lines 7-8 requires “…control is performed in the completing in response that the hydrogen burner fails to be ignited…” and should require “…control is performed in response to the hydrogen burner failing to ignite…”. Lines 22-23 require “…and then returning to the determining the equivalence ratio is performed” and should require “a new equivalence ratio is determined”. Appropriate correction is required. Claim 18 is objected to because of the following informalities: lines 7-8 requires “…control is performed in the completing in response that the hydrogen burner fails to be ignited…” and should require “…control is performed in response to the hydrogen burner failing to ignite…”. Claim Rejections - 35 USC § 112 The following is a quotation of 35 U.S.C. 112(b): (b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph: The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention. Claim 9 is rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention. Claim 9 requires “an amount of the combustion air flowing to be supplied is measured by at least one of the flowing-fluid speed sensor, the pressure sensor, and the mass sensor…” [claim 9 lines 4-5]. The sensors are introduced with respect to the measurement of the flow rate of hydrogen gas in lines 1-3 of claim 9. However, the claim is constructed so that the combustion air flowing speed is measured by the same sensors (as opposed to the same type of sensors) that measure the flow rate of hydrogen. For the purposes of examination the sensors are interpreted to be the same type of sensor as opposed to the same sensor. Claim Rejections - 35 USC § 102 The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action: A person shall be entitled to a patent unless – (a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention. Claim(s) 1 is/are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Nix (US 2024/0255143 A1). With respect to claim 1 Nix discloses a system of preventing backflash in a pre-mixed hydrogen burner [reference character 69]1, the system comprising: the hydrogen burner including a mixture pipe [see annotated Fig. below] connected to a hydrogen supply flow-path tube [reference character 40] along which hydrogen is guided and a combustion air supply flow-path tube [see “air line” in Fig. 3] along which combustion air is guided, wherein a mixture of the hydrogen and the combustion air is combusted at a combustion nozzle end portion [reference character 92] of a pipe [reference character 68] connected to the mixture pipe; and a control unit [reference character 18] configured to perform a first control to purge the pipe and to interrupt supply of the hydrogen, in response that the backflash is likely to propagate from the combustion nozzle end portion to the mixture pipe during the combustion [paragraph 0037]2. PNG media_image1.png 300 524 media_image1.png Greyscale Claim Rejections - 35 USC § 103 The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or nonobviousness. Claim(s) 9 is/are rejected under 35 U.S.C. 103 as being unpatentable over Nix (US 2024/0255143 A1) in view of Tremblay et. al (US 2014/0147795 A1). With respect to claim 9 Nix does not disclose an amount of the hydrogen flowing to be supplied is measured by at least one of a flowing-fluid speed sensor, a pressure sensor, and a mass sensor and is regulated by a fluid control valve, and wherein an amount of the combustion air flowing to be supplied is measured by at least one of the flowing-fluid speed sensor, the pressure sensor, and the mass sensor and is regulated by at least one of an inverter, a damper, and a brushless DC (BLDC) motor. Tremblay discloses a flow rate control system for a flare that includes a flow meter [reference character 180] for measuring the fuel gas flow rate and control valves [reference characters 194 and 204] for controlling the flow rate. Additionally, Tremblay discloses that the combustion air is measured with a pressure sensor [reference character 216] and controlled via a flow regulating damper [reference character 212 and paragraph 0054]. It would have been obvious to one of ordinary skill in the art at the time of the filing date of the invention to modify the system taught by Nix by measuring and controlling the flow rates of air and fuel, as taught by Tremblay in order to control the mixture ratio of fuel and air in order to ensure complete combustion. Allowable Subject Matter Claims 2-8 are allowed. Claims 10-20 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to VIVEK K SHIRSAT whose telephone number is (571)272-3722. The examiner can normally be reached M-F 9:00AM-5:20AM. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Steven B McAllister can be reached at 571-272-6785. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /VIVEK K SHIRSAT/Primary Examiner, Art Unit 3762 1 “In general, hydrocarbon processing sites utilize flares to dispose of undesired speciated organic gases (OGs) via controlled combustion. The OGs may include…H2…” [paragraph 0015]. 2 “In some embodiments, a purge gas 82 may be introduced (e.g., via the liquid seal 80) to provide backpressure on the upstream components of the pre-flare OG treatment 70 and/or to reduce the likelihood of flashback by providing positive flow through the exhaust stack 68 in the scenario of low flow rates of OGs 40 and/or exhaust gas 42” (emphasis added) [paragraph 0037] where the “the scenario of low flow rates of OGs 40 and/or exhaust gas 42” is interpreted as situation where “backflash is likely to propagate from the combustion nozzle end portion to the mixture pipe during the combustion” [claim 1 lines .
Read full office action

Prosecution Timeline

Sep 13, 2023
Application Filed
Nov 15, 2023
Response after Non-Final Action
Mar 28, 2026
Non-Final Rejection — §102, §103, §112 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
74%
Grant Probability
99%
With Interview (+28.5%)
3y 0m
Median Time to Grant
Low
PTA Risk
Based on 1061 resolved cases by this examiner. Grant probability derived from career allow rate.

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