US 11402303

I'll search for authoritative information on this specific patent number.

Let me run a few more targeted searches to check for litigation/docket activity and USPTO records.

US Patent 11,402,303 — Analyst Summary

Search provenance and limits

• Primary source (authoritative): Google Patents full-text record for US11402303B2, fetched 2026‑09‑24. All bibliographic data and claim text below are taken from that record.
• Corroboration: Justia Patents "Patents Assigned to CEMTEK Systems Inc" listing and the Justia page for the related US 11,852,569 confirm the same title/abstract and family.
• Not found: I found no CAFC 2026 docket activity for this patent number, and no litigation hit in my searches. Absence of a result is not proof of non-litigation — I cannot confirm from the sources retrieved that this patent is or is not involved in any Federal Circuit or district court proceeding. Treat the "no litigation" point as unverified.
• Literal-ID caution: A search for the bare string "11402303" surfaced a Plainsite assignment record reading "Patent Application No. 11402303, Filed April 10, 2006" for "Apparatus For Cleaning A Diesel Particulate Filter With Multiple Filtration Stages" (Cleaire Advanced Emission Controls). Per the strict-ID rule I did not auto-correct or discard this: it is a different identifier type — an 8‑digit application serial (11/402,303), not US Patent No. 11,402,303. It is a false positive, not an alternate record for the patent at issue.

---

Bibliographic data

---

Abstract

"Disclosed is a system and method for low-pressure, low-flow dilution extraction. The system includes an outer housing, an inner housing partially within a heating element, and a manifold connected to the inner housing, having taps for a sample nozzle and dilution nozzle, and a through hole connecting the sample and dilution nozzle taps to allow a sample gas from, e.g., a stack to mix with a dilution gas before being drawn at a low pressure towards a gas analyzer."

---

Claims of record (9 total; 2 independent)

Independent claim 1 — Probe end assembly

A low-pressure, low-flow dilution extraction gas probe end assembly comprising, in combination:

1. Outer probe housing defining an internal cavity, open at a first end and a second end;
2. a helical heating element inside that internal cavity;
3. an inner probe housing at least partially inside the helical heating element, with a first open end insertable into the first-end opening of the outer housing and a second open end facing the outer housing's second-end opening;
4. a calibration tee inside the inner probe housing, having a first port (sample gas), a second port (calibration gas), and a third port;
5. a temperature- and pressure-regulated sample nozzle inside the inner probe housing, with an inlet operably connected to the calibration tee's third port and adapted to receive sample gas;
6. a temperature- and pressure-regulated dilution nozzle adapted to receive a dilution gas;
7. a manifold connected to the second open end of the inner probe housing and operably connected to both nozzles, configured to direct the dilution gas to mix with the sample gas; and
8. a first duct connected to a manifold outlet and adapted to receive the sample/dilution gas mixture.

Plain language: the patent's core hardware claim — a compact, internally heated probe tip in which a calibration tee feeds a sample nozzle, and a dilution nozzle feeds a manifold where dilution air/gas is mixed with the stack sample right at the probe tip, with the mixed gas drawn out through one duct.

Independent claim 7 — System

A low-pressure, low-flow dilution extraction gas system comprising a probe end assembly according to claim 1, plus a gas analyzer and a vacuum pump operably connected to the first duct of that assembly.

Plain language: takes the claim‑1 probe and adds the downstream analyzer and vacuum pump that pull and measure the diluted sample.

Dependent claims

• Claim 2: adds a probe end cap connecting to the first end of the inner probe housing and adapted to hold a coarse filter allowing sample gas into the inner housing.
• Claim 3: adds a fine filter between the calibration tee's third port and the sample nozzle.
• Claim 4: outer probe housing has inner diameter ≤ 1.5 in and length < 10 in.
• Claim 5: inner probe housing has inner diameter ≤ 1 in.
• Claim 6: manifold contains a through hole for mixing dilution gas with sample gas having inner diameter < 0.1 in.
• Claim 8: (from 7) the outer probe housing is connected to a pipe coupling.
• Claim 9: (from 8) the pipe coupling is operably connected to a probe stinger, and the probe end is positioned inside a stack.

---

Notable drafting/specification observations

1. The claimed method is not in the claims. The specification's "third aspect" describes a method (pass sample gas through a sample nozzle in a manifold inside the stack; form a dilute mixture via a through hole < 0.1 in ID; transport to an analyzer under vacuum sufficient to hold the dew point below a threshold). However, no method claim issues in US 11,402,303 — the granted claim set is limited to the apparatus (claim 1), the system (claim 7), and their dependents. Claim 6 captures only the sub-0.1‑inch through hole numerically.
2. Substantive parameters live mostly in the specification, not the claims. Numbers such as dilution ratio 1:1–200:1, mixture pressure < 0.1 atm (preferably), flow < 100 cc/min, dew point thresholds (30 °F → −25 °F), and heater setpoints (>200 °F, preferably >250 °F, around the manifold/nozzles) appear in the description; only the dimensional limits of claims 4–6 are claim-bound.
3. Two "temperature- and pressure-regulated" nozzles are affirmative claim‑1 elements — note the specification text (and the Google Patents "Definitions" section) renders one instance as "ressure-regulated" (a typo in the source text); the granted claim reads "pressure."
4. Prosecution was quick: filed 2020‑01‑16, non-final action 2022‑01‑27, response 2022‑03‑13, notice of allowance 2022‑03‑31 — roughly a two-month allowance turnaround on the merits.
5. Closest prior art on the face of the patent (Citations list) includes US 5,458,010 (United Sciences, "Vacuum dilution extraction gas sampling system"), US 4,974,455 (Lear Siegler, "Dilution extractive probe"), US 5,037,322 (Voest‑Alpine), and JPH06123683 (Testoterm). Notably, the United Sciences vacuum-dilution-extraction line is the same technical neighborhood described in the '303 background.

Bottom line

US 11,402,303 B2 is a Cemtek Systems patent (inventor Sean D. Mitchell) covering a compact heated dilution‑extraction probe tip assembly and the analyzer/vacuum‑pump system built around it, with dependent claims on filter placement, probe dimensions, sub‑0.1‑inch mixing through‑hole, pipe coupling, and stack mounting. It issued 2022‑08‑02 from a 2020 filing claiming 2019 priority, is currently active with adjusted expiration 2040‑12‑02, and has a divisional sibling (US 11,852,569 B2). I have no authoritative information indicating any CAFC 2026 docket involvement.

I'll search litigation sources for this specific patent number.

Let me search more targeted litigation databases and the patent owner.

Let me check the litigation-specific portals and dockets directly.

Bottom line

I found no litigation involving U.S. Patent 11,402,303. Searches of patent-litigation-oriented sources returned no complaint, docket entry, or case list naming this patent. That is a negative result, not a clean bill of health — I was not able to run a definitive, exhaustive docket query against Docket Navigator, Lex Machina, PACER, or the Unified Patents litigation portal (which is not readily keyword-indexed by patent number through general web search), so treat this as "no publicly indexed litigation found," with the caveat below.

What I searched and what came back

1. Direct number searches ("11402303" patent litigation, US11402303 lawsuit infringement, "11,402,303"). Only false positives, which I did not count as litigation against this patent:

   • U.S. Application No. 11/402,303 (Cleaire Advanced Emission Controls / Raul Corona, filed April 10, 2006, "Apparatus For Cleaning A Diesel Particulate Filter With Multiple Filtration Stages"). This is a serial number, and a completely different patent — not U.S. Patent 11,402,303. Note that literal reading matters here: 11402303 and 11/402,303 are different identifiers, and I have not conflated them.
   • Litigation/PTAB documents referring to other "'023 patents" (e.g., a Sonos/Linkplay Delaware case over U.S. 10,853,023; an ophthalmic patent family; the Hoffman-Daimler "023" in a femoral-stem case). None involve 11,402,303.
   • Irrelevant numeric collisions (a Hungarian MTMT SJR rating ID, an OCLC number, a Brazilian exam ID).

2. Patent-owner searches (Cemtek Systems patent lawsuit infringement, unifiedpatents.com litigation Cemtek Systems, courtlistener "Cemtek Systems" patent complaint). Cemtek Systems Inc. appears in the record only as a patent owner and a vendor of continuous emissions monitoring systems (CEMS) — e.g., Cemtek Environmental, Inc. municipal software-support contracts (Riverside, CA; JEA/Jacksonville, FL) and assignment records to CEMTEK Systems Inc / "CEMTEK SYSTEMTS INC" (reel/frame 052234/0891 and 052234/0963, effective 2020-03-20). No infringement suits by Cemtek surfaced.

3. Patent-record context from the authoritative patent text (the Google Patents page you provided), which shows no litigation signal:

   • Assignee: Cemtek Systems Inc (small entity); inventor Sean D. Mitchell.
   • Post-grant activity listed: no litigation events. The only third-party citation of this patent is US20230085113A1 / US12625040B2 (Flo2R ApS, priority 2020-01-13, "Gas sampling apparatus for extraction of gaseous samples") — that is a citation, not an enforcement action, and does not indicate a suit over 11,402,303.
   • Related family: continuation/divisional US 11,852,569 B2 (application 17/847,786, filed 2022-06-23) from the same family (ID 71608825), claiming priority to provisional 62/794,822 (2019-01-21). No litigation is recorded there either.
   • Prosecution was short (filed 2020-01-16; non-final action 2022-01-27; response 2022-03-13; allowance 2022-03-31; grant 2022-08-02), consistent with a product-driven filing rather than a litigation-acquisition filing. Maintenance fee for year 4 paid 2025-11-13; status Active, adjusted expiration 2040-12-02.

Requested table

Caveats and how to confirm (recommended next steps)

• Because the patent issued only on 2022-08-02 and is held by a small-entity operating company (not an NPE), a litigation-free record to date is plausible, but I cannot certify it from the sources I could reach.
• For a definitive answer, run the patent number as a "patent asserted" filter in Docket Navigator, Lex Machina, or Unified Patents' litigation portal (portal.unifiedpatents.com/litigation/caselist), and search PACER and CourtListener/RECAP dockets for "Cemtek" as plaintiff. Also check USPTO Patent Trial and Appeal Board (IPR/PGR) and USPTO assignment records, since a suit could trigger an IPR that would not appear as district-court litigation.
• If you want, I can attempt those targeted database queries directly (e.g., Unified Patents caselist, CourtListener docket search for "Cemtek Systems") in a follow-up pass — I hit a tool-step limit before completing them here.

One clarification for the file: the patent's front page does not list any litigation, and the only related-party post-grant publication is the Flo2R Aps family cited by this patent's examiner/third parties — no adversarial proceeding involving 11,402,303 is evidenced in the record you supplied.

Proceedings overview

Total AIA trial proceedings on file for US 11,402,303: 0 — zero IPRs, zero PGRs, zero CBMs, no institution decisions, no Final Written Decisions, no settlements, and no Federal Circuit appeals. The structured "PTAB proceedings on file" block (USPTO Open Data Portal, most recent ingest) returns an empty proceeding set, and independent web searches for PTAB challenges to this patent returned nothing; the only PTAB-adjacent hits were unrelated patents that happen to share a similar-looking number (see the caution note below). Defensive posture for a defendant: the patent is untested at the Board — there is no cancelled-claim ammunition to point at, but also no PTAB record showing the claims are vulnerable. Validity has never been litigated in an AIA trial.

Because there are no proceedings, the per-proceeding template has no entries to populate. Rather than fabricate dockets, I've documented the negative finding, its evidentiary basis, and what it means.

---

Caution: do not confuse this patent with US 11,447,023

Web search for "11,402,303 IPR" surfaces a different patent with a re-arranged number: US 11,447,023 ("the '023 patent" in that record), which is the subject of IPR2024-00577, ADC Solutions USA, LLC v. The NOCO Company — a portable battery jump-starter patent asserted in The NOCO Company v. Winplus North America Inc., No. 8:23-cv-00269 (C.D. Cal.) and ITC Inv. No. 337-TA-1359. That proceeding, its exhibits, and any outcomes have nothing to do with US 11,402,303 (Cemtek Systems, gas sampling). If a docket-research vendor or an AI summary hands you "IPR2024-00577" as prior art/estoppel material against the Cemtek patent, it's a mis-numbering artifact. Treat it as a false positive.

---

What the record does show for US 11,402,303

• Patent: US 11,402,303 B2, "System and method for low pressure low flow dilution extraction gas sampling"
• Application: 16/744,451; filed 2020-01-16; priority to provisional 62/794,822 filed 2019-01-21
• Granted: 2022-08-02; current status: Active; adjusted expiration 2040-12-02
• Assignee: Cemtek Systems Inc (New Jersey); inventor Sean D. Mitchell
• Claim set: 9 claims — claim 1 (probe end assembly), claim 7 (system: assembly + gas analyzer + vacuum pump), claims 2–6 and 8–9 dependent
• Family: continuation/divisional US 11,852,569 B2 (application 17/847,786, filed 2022-06-23, granted 2023-12-26). It likewise shows no AIA trial proceedings.
• Forward citation of note: US 2023/0085113 A1 / US 12,625,040 B2, Flo2R ApS, "Gas sampling apparatus for extraction of gaseous samples" (priority 2020-01-13) — a patent-family citation, not a validity challenge. Flo2R is not a petitioner against this patent on the record.
• Maintenance fee: 4th-year fee paid 2025-11-13 (small entity) — the patent is being actively maintained, which is consistent with a commercially enforced asset.

Conclusion on the proceedings list: no PTAB activity on file. The default stated in the prompt holds.

---

Strategic summary

Claim status: everything is UNTESTED. All nine claims — independent claims 1 and 7, and dependent claims 2–6, 8, and 9 — stand as issued. None has been cancelled, disclaimed, or amended through an AIA trial. There is no certificate of correction or reexamination record surfaced in the structured data either. The practical consequence is double-edged: a defendant cannot say "claim 1 is already dead," but the patent owner also cannot point to a Board decision upholding the claims against a skilled challenger. The claims are whatever the original prosecution produced, and the prosecution was short — a non-final action mailed 2022-01-27, a response entered 2022-03-13, and a notice of allowance mailed 2022-03-31, roughly two months later. That thin prosecution history means the intrinsic record is compressed, which cuts both ways on claim construction and on § 325(d)/Advanced Bionics arguments if a petition is ever filed.

Estoppel landscape: empty. Section 315(e)(2) estoppel attaches only to a petitioner that reaches a Final Written Decision (or that settles after institution), and no such petitioner exists. No prior-art ground, statutory basis, or claim is off the table by estoppel for any defendant. Every path remains open: § 102/§ 103 IPR petitions on patents/publications, § 112 challenges, and — critically — PGR is not available (the 9-month post-grant window from 2022-08-02 closed in May 2023), and CBM is unavailable because the patent is not a "covered business method" claim and the CBM program has sunset for petitions filed after 2020-09-16. So IPR is the only realistic AIA route, and any IPR petition filed now must clear the § 315(b) one-year bar measured from service of a complaint alleging infringement of this patent (or its family member, per Click-to-Call line of analysis for service on the patent, not the family — that nuance is worth checking against whichever complaint your client actually received).

Pattern signals: none. No petitioner has filed once, let alone multiple times. The patent owner has not appeared before the Board in any capacity on this patent, so there is no evidence of aggressive PTAB-appeal behavior — no ex parte appeal history, no FWD appeals, no Director Review requests. No defensive aggregator (Unified Patents, RPX, Open Invention Network, etc.) appears anywhere in the chain. The absence of a Unified Patents challenge is notable only in the negative direction — this is a low-volume, industrial CEMS patent that simply hasn't attracted a crowd-funded challenger. The absence is a signal, but a weak one: well-asserted patents tend to attract IPRs, and the fact that this one hasn't suggests either that Cemtek enforces quietly through commercial channels and customer contracts (its CEMS/DAHS business, e.g., the City of Riverside DAHS software support contract approved 2025-02-10, is a service-and-software model), or that no litigation defendant has yet found the invalidity art attractive enough to file.

---

Recommended next steps

If you are a defendant and you received a demand letter citing US 11,402,303. There is no FWD and no cancelled claim to quote — do not build any argument on a PTAB record, because none exists. What you can do:

1. Verify the assertion. Pull the complaint or letter and confirm it identifies US 11,402,303 (and, if applicable, the sibling US 11,852,569). The two patents share the 2019-01-21 priority date and substantially overlapping disclosures, so an assertion may target both — they must be analyzed separately.
2. Start a prior-art search now, against the 2019-01-21 priority date. The patent's own face cites the most relevant field art, and it is your best starting map: US 4,974,455 (Lear Siegler, "Dilution extractive probe"), US 5,458,010 (United Sciences, "Vacuum dilution extraction gas sampling system"), US 5,039,322 (Voest-Alpine, hot gas extraction), JPH06123683 (Testoterm, flue gas sampling), US 6,200,819 (Horiba, diluent gas to exhaust analyzer), and US 8,511,141 (Brand-Gaus, stack gas measurement). The examiner had these on the record, so a § 325(d) discretion argument would weigh against institution if a petition leans on them without materially new teaching — you'll need art the examiner did not consider, or a materially new reading of what these references disclose.
3. File within the § 315(b) window. Once your client is served with a complaint alleging infringement of this patent, the one-year clock starts. No petition can be salvaged after it — the Board has no discretion to excuse it, and joinder to an existing trial is unavailable here because there is no existing trial to join.
4. Consider whether you actually need the IPR. With no litigation track record on this patent, district-court invalidity, inter partes reexamination, and design-around may all be cheaper than a full IPR. Reexamination has no § 315(b) bar and no estoppel, which is an underused lever against a patent with no PTAB history.

If you are a defendant and active proceedings are pending. None are. There is no institution deadline, no oral hearing date, and no statutory 1-year FWD due date to monitor, because no trial has been instituted. Nothing to calendar on the PTAB side.

Monitoring recommendation. Because the patent is active through 2040-12-02 and the family has a live sibling, set a docket alert on (a) the PTAB E2E docket for any new petition naming US 11,402,303 or US 11,852,569 as the challenged patent, and (b) the district-court dockets for Cemtek Systems Inc. as plaintiff. The most likely near-term trigger for an IPR is a competitor's infringement suit, not a defensive aggregator filing.

Bottom line: no PTAB activity exists on US 11,402,303 as of the most recent ingest. That is the complete answer. Everything above about claim 1, claims 2–6, and claims 7–9 is a statement about absence of adjudication, not a statement about validity — treat the claims as fully live, presumptively valid under § 282, and unchallenged.

I'll start by verifying the assignment record and checking for litigation/NPE signals via web sources, then build the report.

Let me dig into the assignment record specifics and Cemtek's corporate profile.

Inventors

Unusual patterns: none detected. A single inventor with no co‑inventor departures, no serial‑number divergence across the family, and an assignment executed shortly after filing. There is no evidence of the "all inventors leave within 12 months" pattern that precedes portfolio fire‑sales — I found no resignation, no second assignment, and no litigation record for this patent in any source I could access.

Original assignee

• Entity on the issued patent: Cemtek Systems Inc (New Jersey). Note the assignee field also carries a variant spelling, CEMTEK SYSTEMTS INC, from a second recording the same day (see timeline) — treat this as a recording typo rather than a distinct entity, but it is a literal discrepancy in the register.
• Status: Active small entity. USPTO fee records show ENTITY STATUS SET TO SMALL (2020‑02‑04) and a 4th‑year maintenance fee paid 2025‑11‑13; Google Patents lists legal status Active, adjusted expiration 2040‑12‑02.
• Line of business / product: The patent is directed to a probe end assembly for dilution‑extraction CEMS (continuous emissions monitoring) in flue‑gas stacks. The disclosure reads as a working hardware design (thread sizes, socket‑head screw specs, M20×1.5 threads, 316SS materials, wrench flats on the end cap), which is characteristic of an operating instrumentation supplier, not a paper portfolio.
• Confidence caveat: I could not verify from an authoritative source (SEC filing, corporate registry, or press release) that Cemtek Systems Inc currently ships a commercial product practicing these claims, and I could not confirm its current corporate status. My searches for acquisition/bankruptcy/dissolution coverage returned nothing. Do not treat the "operating" characterization above as confirmed by a filing — it is inferred from the patent's engineering specificity, small‑entity status, and the absence of any transfer.

Assignment timeline

Only one transfer event is recorded, appearing as two register entries on the same date with the same effective date. There are no post‑issuance assignments — this is itself the principal finding: the patent has never left its original owner.

• 2020‑03‑20 (executed) / recorded 2020‑03‑26 — Reel 052234/0963

  • Conveyance: Assignment (of assignor's interest)
  • Assignor: Mitchell, Sean D.
  • Assignee: CEMTEK SYSTEMS INC (New Jersey)
  • Correspondent: Not retrievable from the sources available to me. The Google Patents legal‑events extract and the assignment metadata I could reach do not expose the correspondent/attorney of record field, and I could not pull the recorded coversheet image. I will not guess a name. This should be pulled directly from the Patent Assignment Center record for reel 052234/0963 to complete the file.
  • Context: Original employment/obligation‑to‑assign transfer from the sole inventor to the company that filed the application.

• 2020‑03‑20 (executed) / recorded 2020‑03‑26 — Reel 052234/0891

  • Conveyance: Assignment (duplicate/parallel recording)
  • Assignor: Mitchell, Sean D.
  • Assignee: CEMTEK SYSTEMTS INC (New Jersey) — literal register spelling
  • Correspondent: Not retrievable from available sources (same caveat as above). Because both entries share the same execution date and recording date and vary only in reel/frame and a one‑character assignee spelling, this is almost certainly the same instrument recorded twice or a name‑correction pair rather than a second genuine conveyance.
  • Context: Internal recording correction / duplicate — not a change of ownership.

Follow‑on record (not an assignment): a divisional child, US 17/847,786, published as US 2022/0316998 A1 and granted as US 11,852,569 B2 (2023‑12‑26), shares the same 2019‑01‑21 priority date and the same title. It is a division, not an assignment, and does not move ownership.

For completeness: the "Cited By" entries (US 2023/0085113 A1 and US 12,625,040 B2, both Flo2R Aps) are third‑party citations to this patent, not assignments involving it. No Flo2R assignment to or from Cemtek appears in the record.

Timeline diagram

timeline
    title Ownership of US 11402303
    2019 : Provisional filed 62/794822
    2020 : Non provisional filed 16/744451
         : Inventor assigns to Cemtek Systems Inc
         : Recorded twice reel 052234 0891 and 0963
    2022 : Patent US11402303B2 issued
         : Divisional filed 17/847786
    2023 : Division issues as US11852569B2
    2025 : Maintenance fee paid 4th year

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The only recorded assignee is Cemtek Systems Inc, the same entity that filed the application and that holds small‑entity status. No "IP / Holdings / Licensing / Ventures" successor appears at reel 052234/0891 or 052234/0963, and there is no later link in the chain at all.

2. Known asserter in the chain — not present. Neither assignee entry matches Acacia, Marathon, Intellectual Ventures, IPNav, Wi‑LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, or any Eric Spangenberg‑linked entity. Nothing in the Flo2R citation activity involves this patent's owner.

3. Repeat correspondent across the chain — cannot be assessed / not present. The chain has only one genuine transfer, so recurrence is structurally impossible here. Additionally, I could not retrieve the correspondent of record for reel 052234/0891 or 052234/0963 from the sources available. One appearance is not a finding under the stated rule in any event.

4. Cascading transfers — not present. There is exactly one executed transfer (2020‑03‑20), duplicated on the register. Zero chained LLC hops; nothing within 24 months of anything.

5. Pre‑litigation transfer — not present. I found no infringement suit naming US 11,402,303. The only transfer is the inventor's original employment assignment, executed 2020‑03‑20 and recorded 2020‑03‑26, i.e., before issuance (2022‑08‑02) by 2.4 years and unrelated to any litigation timing.

6. Bankruptcy fire‑sale — not present. No Chapter 7/11 record, no stalking‑horse sale, no assignment out of an estate. The assignee is active and paying maintenance fees.

7. Privateering — not present. No operating company is asserting through an NPE proxy; there is no downstream NPE at all, and no SEC or third‑party coverage indicating one.

8. Defensive aggregator — not present. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN. The patent remains with its original operating assignee.

Verdict

Insufficient data (the only recorded instrument is the original inventor‑to‑assignee assignment).

The assignment record for US 11,402,303 consists solely of the founder/employee assignment from Sean D. Mitchell to Cemtek Systems Inc, executed 2020‑03‑20 and recorded 2020‑03‑26 at reel 052234/0963 (with a duplicate spelling‑variant entry at reel 052234/0891). There are zero post‑issuance assignments, no shell‑entity hop, no known asserter, no cascading transfers, and no litigation I could locate — so despite the patent's active status and 2040‑12‑02 adjusted expiration, there is no evidence-based basis to classify this as an NPE holding. Substantively, this looks like an operating instrumentation supplier retaining its own patent; the formal verdict is "insufficient data" only because the chain contains a single link.

Two items to close the file (I could not retrieve them within my search budget and will not fabricate them):

1. The correspondent of record on reel 052234/0891 and 052234/0963 — pull the coversheet images at the Assignment Center; this is the one field the NPE‑pattern analysis depends on that is still blank.
2. Confirmation of Cemtek Systems Inc's current corporate status and product line, ideally from a New Jersey corporate registry record or the company's own site.

Verify at: https://assignmentcenter.uspto.gov/ (search patent number 11402303) and https://patents.google.com/patent/[US11402303B2](/patent/US11402303B2)/en

I'll verify the patent record and then examine each cited reference. Let me start with searches.

Let me examine the key dilution-extraction references in more depth.

Now let me verify the remaining cited references.

Prior-Art Analysis — US 11402303 B2

Important limitations on this analysis, stated up front:

1. I was able to retrieve the full text and citation/legal-events record of US11402303B2 (Google Patents, fetched 2026‑09‑24) and full or near‑full text for US4974455A, US5458010A, US5039322A, and US8511141B2. For the remaining cited references I have only bibliographic data and title‑level descriptions, and I could not retrieve the substantive text or the actual USPTO Office Action / file wrapper in this session. Where my description of a reference rests only on its title, I say so.
2. Under 35 U.S.C. § 102, a reference anticipates a claim only if it discloses every limitation. Because claims 2–9 all depend from claim 1, no reference can anticipate claims 2–9 unless it also anticipates claim 1. I therefore report (a) whether each reference anticipates claim 1, and (b) which claim‑1/dependent‑claim features each reference supplies (the real value of these citations is as § 103 combination art). I flag where a § 102 rejection would be legally unavailable.
3. Identifiers are reproduced literally, including the apparent typo in the assignment record ("CEMTEK SYSTEMTS INC").

---

1. Record verification for US 11402303

Claim architecture (9 claims): Claim 1 is the sole independent apparatus claim (outer probe housing with cavity/openings → helical heating element in the cavity → inner probe housing at least partly within the heating element → calibration tee within the inner housing (three ports) → temperature‑ and pressure‑regulated sample nozzle in the inner housing, inlet tied to the tee's third port → temperature‑ and pressure‑regulated dilution nozzle → manifold connected to the inner housing's second open end, plumbed to both nozzles and configured to mix dilution gas with sample gas → duct from the manifold outlet). Claim 2 end cap + coarse filter; claim 3 fine filter between tee third port and sample nozzle; claim 4 outer housing ID ≤ 1.5 in / length < 10 in; claim 5 inner housing ID ≤ 1 in; claim 6 manifold through‑hole ID < 0.1 in; claim 7 system = claim‑1 assembly + analyzer + vacuum pump; claim 8 pipe coupling; claim 9 coupling + probe stinger + probe end inside a stack.

Key signal for prior‑art focus: in the citation tables, exactly four references carry the "cited by examiner" indicator (the *): US5039322A, US4974455A, US5458010A, and JPH06123683A. Those are the references the examiner actually relied on; the other 14 appear to be applicant/third‑party citations. My ranking below reflects that.

---

2. Complete citation list with dates and descriptions

All 18 predate the 2019‑01‑21 priority date, so each is presumptively available as § 102 prior art (printed publication / patent, subject to the usual verifications for pre‑AIA vs. AIA timing and for foreign‑language documents).

---

3. The four examiner‑cited references — element‑by‑element

3.1 US4974455A — Dilution extractive probe (Lear Siegler Measurement Controls Corp.)

Filed 1989‑08‑29; granted 1990‑12‑04.

Disclosure: A hollow tubular dilution probe sampling a stack gas stream. A first filter at the probe's first end, a critical orifice (64) downstream of it, a first heater (48) to keep the sample above the dew point, and a second cylindrical sintered‑metal filter with a closed end and open end positioned over the first end (with a protective shroud, and an end cap 33). At the downstream end, a primary nozzle (70) mixes sample gas with dilution gas drawn via passageways (72, 73, 74); mixing is completed in an eductor (75) at sonic speed, and the mixed gas goes via conduit 76 to analyzer 100. A second heater (78) surrounds the downstream housing and a thermocouple (80) controls it. Calibration/zero gas is introduced either through passageway 82 (purging chamber 56 and forcing gas out the coarse filter) or through conduit 84 at end cap 33. A support flange (28) attaches the probe assembly to the stack, and a vacuum gauge line (83) measures probe pressure. Dilution control panel 96 senses/regulates sample and eductor pressures.

§ 102 mapping to claim 1 — does not anticipate. Missing at least: an inner probe housing nested inside an outer probe housing with the heating element between them (the reference uses a single tubular housing with a conduit support 59 routing internal lines); a helical heating element inside the outer housing cavity; a calibration tee within the inner probe housing with first/second/third ports (calibration is injected into the filter chamber, not through a tee feeding a sample nozzle); a distinct sample nozzle whose inlet is connected to the tee's third port; and a manifold connected to the second open end of an inner housing with sample/dilution nozzle taps and a through‑hole. The claim‑1 architecture is a nested, replaceable cartridge; US4974455 is a monolithic heated probe. No anticipation of any of claims 1–9.

Where it remains dangerous (feature‑level):

• Claim 2 (cap + coarse filter): the closed‑end/open‑end second filter plus protective shroud, and the removable end cap 33, are close structural analogues → strong § 103 art.
• Claim 3 (fine filter between the tee and the sample nozzle): the reference's series filter arrangement (coarse filter → critical orifice → nozzle; two filters) supplies the "one, two, or more filters prior to the sample nozzle" teaching.
• Claim 6 (through‑hole < 0.1 in): the critical orifice 64 is the classic sub‑0.1‑inch flow‑restricting element; the reference also expressly controls dew point by heating, which is the stated purpose of the small through‑hole in US11402303.
• Claim 7 (analyzer + vacuum/pressure control): analyzer 100 plus eductor/vacuum‑gauge/control panel.
• Claim 8/9 (coupling, stack mounting): support flange 28 / externally threaded probe support 86; the stack probe is positionable in a stack and flanged to it.
• Claim 1's "temperature‑ and pressure‑regulated" nozzles: dilution control panel 96 senses and regulates sample‑gas and eductor pressures.

3.2 US5458010A — Vacuum dilution extraction gas sampling system (United Sciences, Inc.)

Priority 1991‑11‑12; filed 1994‑03‑28; granted 1995‑10‑17.

Disclosure: Two parallel sonic orifices — one fed by filtered, heated sample, a second larger orifice fed by dilution gas — with a vacuum pump maintaining a substantial vacuum behind the orifices to guarantee critical flow. Sample and dilution gas mix behind the orifices and are transported under partial vacuum to the analyser. Critically: "The dew point of the sample is affected by both the ratio of the diameter of orifices and the degree of vacuum transporting the gas mixture. As such, the dew point can be varied indefinitely by any reasonable combination of orifice ratio and vacuum pump strength." The specification also describes and criticises the traditional extractive system, the venturi dilution probe (Fig. 2), and a probe end/mixing chamber (Figs. 4–9).

§ 102 mapping to claim 1 — does not anticipate the nested housing + helical heater + calibration tee + tapped manifold combination. No anticipation of claims 1–9.

Why it is nonetheless the single most relevant reference to the inventive concept:

• It is the closest art to the "low‑pressure" limitation and to maintaining a vacuum sufficient to hold the mixture's dew point below a threshold — the express purpose of claim 1's downstream arrangement and of the specification's −10 °F/−25 °F thresholds.
• The dilution ratio set by orifice diameter ratio (sample orifice vs. larger dilution orifice) is directly on point for claim 6's small‑diameter through‑hole, and for the specification's stated 1:1–200:1 dilution ratio.
• Vacuum pump + analyser (claim 7), probe in a stack (claim 9).

Note the family: US5458010A shares priority with US5297432A ("Vacuum dilution extraction gas sampling method") and US5637809A ("Vacuum extraction sampling system"), which appeared in my searches but are not in the US11402303 citation list. They are potentially relevant art that the examiner did not cite here; anyone challenging claim 1 should look at them.

3.3 US5039322A — Apparatus for extracting hot gas samples from a reaction vessel (Voest‑Alpine)

Priority 1988‑01‑11; filed 1989‑01‑10; granted 1991‑08‑13.

Disclosure (verified): An extraction probe (1) with a gas‑conducting inner tube (4), an outer shell (20) that is double‑walled and liquid‑cooled, and heat insulation (21) between the outer shell and the heated inner tube. A heating coil (19) of an electric resistance heater surrounds the inner tube (4) and the filter cup (3) — expressly "operable to prevent a temperature drop below the dew point temperature." A filter cup (3) that is a diametrically enlarged coaxial extension of the inner tube, a filter plug (6), an annular channel (12) with blast nozzles (14) fed by a blast line (16) for purging, a gas exit opening (9), a gas‑delivering line (18), a removable cover (26) over the filter bottom, a mounting flange (10), and a temperature sensor (27). A two‑probe variant is also disclosed.

§ 102 mapping to claim 1 — does not anticipate. It has no dilution gas, no dilution nozzle, no manifold mixing, no calibration tee, and no sample nozzle. No anticipation of claims 1–9.

Why the examiner cited it: it is the only cited reference that discloses the nested‑housing‑with‑heating‑element‑between‑them architecture — outer shell 20 / inner tube 4 / heating coil 19 in between — which is the spatial core of claim 1(b)–(c). It also supplies (i) an outer housing that is a cooled shell vs. an inner heated tube, and (ii) dew‑point‑driven heating, and (iii) a cover/end cap over a filter at the probe end (relevant to claim 2) and a mounting flange (relevant to claims 8/9). It is best understood as the § 103 primary reference for the claim‑1 housing geometry, combined with US4974455A/US5458010A for the dilution and vacuum teachings.

3.4 JPH06123683A — Gas sampling device for flue gas analyzer (Testoterm Fritzsching GmbH & Co)

Priority 1992‑05‑18; published 1994‑05‑06.

I could not retrieve the specification text in this session — the citation is bibliographic only, so I will not characterise its disclosure. From the title and the assignee's field it is a heated flue‑gas sampling device for a flue‑gas analyser, i.e., probe‑with‑filter art. Two practical cautions: (i) relying on it under § 102/§ 103 requires an authenticated English translation/abstract, and (ii) it is relevant only if it discloses dilution mixing in a probe‑mounted manifold — which the title does not establish. I cannot state that it anticipates any claim; treat as unverified.

---

4. Remaining cited references — relevance and potential § 102 mapping

---

5. Conclusion — most relevant prior art, ranked

1. US4974455A (Lear Siegler) — closest structural and functional art: heated dilution‑extractive stack probe, filters, critical orifice, calibration/zero‑gas introduction, mixing at a primary nozzle/eductor, analyzer. Best § 103 primary reference for claims 1–3, 6–9 as a whole, and the strongest single reference on the cite list.
2. US5458010A (United Sciences) — the express teaching of vacuum‑maintained dilution with dew point set by orifice‑diameter ratio and pump strength; directly on point for the "low‑pressure / low‑flow," dilution‑ratio, and dew‑point limitations. Its uncited siblings (US5297432A, US5637809A) should also be reviewed.
3. US5039322A (Voest‑Alpine) — the only cited reference disclosing an inner tube nested within an outer shell with a heating coil between them, plus dew‑point protection, a filter held at the probe end behind a removable cover, and a mounting flange. § 103 primary reference for the claim‑1 housing/heater geometry (claims 1, 2, 8, 9).
4. US8511141B2 (Brand‑Gaus) — dilution immediately at the probe under suction to lower dew point, with independently heated dilution/analysis zones; strong § 103 secondary art.
5. US6200819B1 (Horiba) — diluent‑gas provision to an emission analyser.
6. US3817100A / US6546812B2 / CN106527544A‑B / GB966064A / GB1336253A — flow‑restriction and sonic‑nozzle art bearing on claim 6 and the "pressure‑regulated nozzle" language.
7. JPH06123683A — examiner‑cited but unverified here; obtain the JP specification and a translation before relying on it.

Bottom line on § 102: on the record available to me, no cited reference anticipates any of claims 1–9, and none can anticipate claims 2–9 in any event because they all incorporate claim 1's limitations. The examiner's four *‑flagged citations (US5039322A, US4974455A, US5458010A, JPH06123683A) are best read as the § 103 combination backbone — nested heated housing (US5039322A) + heated dilution extraction with calibration and filtration (US4974455A) + vacuum‑maintained, orifice‑metered dilution (US5458010A) — combined against the narrower claim‑1 features (calibration tee within the inner housing, sample nozzle inlet tied to the tee's third port, manifold tapped for both nozzles with a sub‑0.1‑inch through‑hole at non‑parallel/non‑perpendicular orientation).

Worth flagging outside the citation list: the § 102/§ 103 exposure of the child divisional US11852569B2 (granted 2023‑12‑26) is separate from this analysis; and Flo2R's US20230085113A1 / US12625040B2 (priority 2020‑01‑13) cite US11402303B2 but post‑date its 2019‑01‑21 priority, so they are not prior art to it (they are, however, potentially relevant inter partes).

Caveats: This is a technical prior‑art assessment, not legal advice. A definitive § 102/§ 103 determination requires the USPTO file history (the 2022‑01‑27 non‑final action and the 2022‑03‑13 response), full texts of the seven references I could only identify bibliographically, certified translations for the JP/KR/CN/GB documents, and claim charts. Corrections to any of the above based on the file wrapper are welcome.

I'll ground the obviousness analysis in the actual prior-art references on the patent's face. Let me pull details on the closest ones.

Now let me pull the remaining face-cited references relevant to the claim elements (housing/heat, calibration tee, stack mounting).

Let me pull the remaining face-cited references — the flue-gas/stack-focused ones.

Obviousness Analysis — U.S. Patent No. 11,402,303 B2 under 35 U.S.C. § 103

Scope note. This analysis builds on the claim set and bibliographic record set out in the previously-generated sections and does not repeat them. It uses the references listed in the "Citations (17)" / "Patent Citations (18)" section of the Google Patents record for US 11,402,303 (https://patents.google.com/patent/[US11402303B2](/patent/US11402303B2)/en), plus one reference appearing in that same page's "Similar Documents" section (flagged where used). Where I could only obtain a title/abstract for a face-cited reference, I say so and mark the mapping provisional.

---

1. Legal framework and the examiner-cited core

The four references on the face of the '303 bearing the Google Patents "cited by examiner" asterisk are:

The fact that the examiner had these four in the record and the application nonetheless issued on 2022‑08‑02 (allowance issued 2022‑03‑31, roughly two months after the 2022‑03‑13 response) tells us the rejection of record was answered by amendment or argument. I do not have the prosecution history (Office action or applicant remarks) and I cannot retrieve it from the sources available to me — so the specific gap the examiner accepted is unverified. What follows is therefore a defensive/validity-style §103 analysis: where would a well-supported obviousness case lie, and how strong is it.

The governing standard is Graham v. John Deere, 383 U.S. 1 (1966), applied through KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007), and MPEP § 2143. The relevant rationales are (A) combining known elements per known methods to yield predictable results; (B) simple substitution of one known element for another; (C) use of a known technique to improve similar devices in the same way; (D) applying a known technique to a known device ready for improvement; (E) "obvious to try" over a finite set of identified, predictable solutions; and (F) design incentives/market forces.

Analogous art. Every reference relied on below is from the same field of endeavor as the '303 — extractive / dilution-extractive sampling of stack, flue, and process gas, classified in G01N 1/22 and its subclasses (the '303's own CPC: G01N 1/22, 1/2247, 1/2258, 2001/2261, 2001/2264, 2001/2285, 2001/2288, 1/38). Under In re Bigio / MPEP § 2141.01(a), all are analogous art on the face of the references themselves; no field-of-invention dispute arises.

---

2. Element-by-element mapping of claim 1

Claim 1's eight body elements mapped to the art (the preamble — "low-pressure, low-flow dilution extraction gas probe end assembly" — is a statement of intended use and structurally adds nothing over the prior art discussed below):

Result: only elements (b)+(c) — the helical heater inside an outer housing with the inner housing inside the heater — and (d) — a calibration tee inside the inner housing — lack a clean single-reference mapping in the United States Sciences and Lear Siegler references. Both are supplied by Voest‑Alpine and Lear Siegler respectively, as detailed in §3.

---

3. Primary combination: US 5,039,322 + US 5,458,010 + US 4,974,455 (optionally + JPH06123683)

3.1 What each reference contributes

(1) US 5,039,322 (Voest‑Alpine) — the housing/heater architecture. Voest‑Alpine's express claim 1 (http://patentimages.storage.googleapis.com/69/30/b7/68081517d4e97d/US5039322.pdf) recites "extraction probe means including a gas-conducting inner tube, heating means for heating said inner tube, outer shell means surrounding said inner tube, cooling means for cooling said outer shell means, and heat insulation between said inner tube and said outer shell means." The specification adds that "the inner tube 4 … and the filter cup 3 … are surrounded by a heating coil 19 of an electric resistance heater, which is operable to prevent a temperature drop below the dew point temperature," and that "heat insulation 21 is provided between the inner tube 4 … and the outer shell 20."

That is, verbatim, claim 1's (a)+(b)+(c) sandwich: an inner tube nested inside a coiled (i.e., helical) resistance heater, nested inside an outer shell. The Voest‑Alpine family's related U.S. 4,756,200 (Ramsner) states the same point as a purpose statement: "the inner tube is provided with heating means and is shielded by heat insulation from the cooled outside surface of the probe."

(2) US 5,458,010 (United Sciences) — the low-pressure, low-flow dilution core and every operating parameter the specification recites. From the reference text (https://patents.google.com/patent/[US5458010A](/patent/US5458010A)/en; https://www.freepatentsonline.com/[5458010](/patent/5458010).html):

• "a pair of parallel sonic orifices. One of the orifices is connected to a source of filtered, heated samples. The second, larger orifice is connected to a source of dilution gas" → claim 1's sample nozzle + dilution nozzle + manifold.
• Conduits 57 and 62 "intersect downstream of the orifices, forming mixing conduit 67 where mixing of the sample and dilution gas occurs" → claim 1's manifold "configured to direct the dilution gas to mix with the sample gas," and its outlet duct.
• "Orifice 58 may be as small as 0.0009 inches which corresponds to a flow rate of 4.2 cc per minute" → the specification's "<100 cc/min" flow; and 0.0009 in. is far below claim 6's 0.1 in. limit.
• "by suitable selection of the orifices, it is possible to achieve any desired volumetric dilution ratio over a range of 1:1 to 250:1" → the specification's "dilution ratio … between 1:1 and 200:1" is fully subsumed.
• "bottled dilution gas from gas cylinders … compressed air, carbon dioxide and nitrogen" → the specification's dilution gas "compressed air and/or nitrogen" from a "compressed gas cylinder."
• "A temperature of 250° F. has been found suitable" in heated chamber 66 → the specification's preferred "above 250 degrees F." around the manifold/nozzles.
• "the dilution ratio should be chosen such that the dew point is lowered to below 30° F." and "sample pump 48 transports the mixture under a substantial vacuum (0.15 atmospheric pressure)" → the specification's dew-point thresholds (30 °F → −25 °F) and mixture pressure "less than 1 atm, preferably ≤ 0.5, more preferably ≤ 0.25, and still more preferably ≤ 0.1 atm." 0.15 atm literally falls within the specification's "≤ 0.25 atm" tier.

(3) US 4,974,455 (Lear Siegler) — the calibration tee, the filter stack, the probe-in-stack architecture, and the analyzer duct. From the reference text (https://patents.justia.com/patent/[4974455](/patent/4974455); https://companyprofiles.justatic.com/patent/4974455):

• "a calibration line/zero gas passageway 82 also extends through the conduit support 59 and through connector 58 into the area within housing 56 adjacent fitting 66. In order to calibrate the probe P, gas can be provided through conduit 82…" plus a second, higher-flow calibration route, "conduit 84 which passes through end cap 33 … and communicates with space 39." This gives a first port (sample/stack gas), a second port (calibration gas), and a third (outlet to the critical orifice/nozzle) — the functional content of claim 1's "calibration tee."
• Coarse filter 60 at the gas-entrance end, with end cap 33; critical orifice 64 downstream; primary nozzle 70 where "the stack gas is mixed with a dilution gas"; eductor 75; conduit 76 "to an analyzer"; heaters 48/78 with thermocouple 80 for closed-loop temperature regulation.
• The probe is a stack-mounted assembly with support flange 28 and threaded probe support 86 — the antecedent for claims 8–9.

(4) JPH06123683 (Testoterm), a flue-gas-analyzer sampling device, is a secondary reference confirming that the sub-combination of a dilution/sampling nozzle arrangement in a flue-gas analyzer probe was known. I could obtain only the title/assignee/date, so I treat it as cumulative and do not rest the rejection on it.

3.2 Motivation to combine (with the references' own words)

Motivation need not be in the references (KSR), but here it is:

1. US 5,458,010 itself frames the problem and the two candidate architectures. Its Background expressly discusses "the traditional extractive system" (FIG. 1) and "the venturi dilution probe system" (FIG. 2) — the latter being precisely the Lear Siegler eductor-probe architecture — explains the drawbacks of each, and presents the two-orifice vacuum-dilution design as the improvement. A POSA reading the '303's own Background (which recites the same EPA 40 CFR compliance-monitoring context, the same "fossil-fueled power plants," and the same SO₂/HCl/HCN analyte list) is being pointed directly at United Sciences as the starting point.
2. A common problem, common solution: dew-point control in a heated probe. Voest‑Alpine's stated object is "a formation of condensate in the inner tube of the cooled extraction probe can reliably be precluded" — the identical problem the '303 states (avoid condensation; maintain dew point below a threshold). Lear Siegler's heaters exist for the same reason ("to maintain the sample gas at the appropriate temperature as it passes through the primary nozzle and the eductor").
3. Express design incentive — low flow and low pressure. US 5,458,010: the low orifice flow "is much less than the minimum 20 cc per minute used in the venturi dilution system," and "it is possible to use bottled dilution gas from gas cylinders instead of plant instrument air or compressor air. This completely eliminates problems with contamination in the dilution gas." That is the motivation for the '303's "low-pressure, low-flow" framing and for its dilution-gas selection, stated in the reference.
4. Predictable, mechanical combination. Bolting a coiled calrod heater into the annular cavity between an inner tube and an outer housing (Voest‑Alpine) onto a dual-orifice dilution probe (United Sciences) requires no new principle of operation; the heater merely maintains the temperature of components that US 5,458,010 already places in a 250 °F "heated chamber 66." The result — a heated dilution probe tip — is the predictable aggregate of two known thermal solutions.

---

4. Alternative and backup combinations

A fallback single-reference-plus-common-knowledge case exists for claim 7: US 5,458,010's system already includes "sample pump 48"/"vacuum pump" and transport "for analysis," and US 4,974,455 adds analyzer 100 — so "a gas analyzer and vacuum pump operably connected to the first duct" is a straight substitution of known downstream components.

---

5. Dependent claims 2–6, 8, 9

Claim 2 (probe end cap + coarse filter). US 4,974,455's end cap 33 carries the coarse filter 60 and even routes calibration conduit 84 through it; Voest‑Alpine's filter bottom is "detachably secured to a mounting flange 10 of the filter cup 3 by means of screws 11," with a "detachably mounted, heat-insulated cover"; US 5,178,022 (see §6) teaches a coarse filter with blowback. Combining a detachable filter-holding end cap with the United Sciences/Lear Siegler probe is a design choice with predictable results.

Claim 3 (fine filter between the third port and the sample nozzle). Lear Siegler places a filter/glass orifice in the same downstream position. US 5,458,010's orifice 58 is protected by prior filtering ("One of the orifices is connected to a source of filtered, heated samples"). Critically, US 5,178,022 ("Inertial filtration external dilution probe") articulates the very motivation for this claim in a dilution probe: prior systems "utilize a coarse or primary stack gas filter and a second or fine filter, and while these systems calibrate through the second filter, they do not calibrate through the coarse or primary filter," and it discloses "a machined passage 52 having a filter 54 and critical orifice 56 located within."

Claims 4 and 5 (outer housing ID ≤ 1.5 in/ < 10 in; inner housing ID ≤ 1 in). These are bare dimensional ranges with no asserted criticality. Under In re Aller and In re Peterson, and MPEP § 2144.04, establishing a range in a known structure is obvious absent evidence that the specific limits are result-effective and unexpected. The art is already at these scales: US 5,458,010's sample flow of 4.2 cc/min and orifice diameters of 0.0009–0.0045 in. imply a very small-bore probe; US 5,178,022 states "Because of the compact size of the probe assembly, it is also possible to enclose the entire analysis unit in a single housing," and a US 5,178,022-family dilution tunnel is described as "only 356 mm (14 inches) at a maximum diameter of about 63.5 mm (2½ inches)" (EP 0 547 050 B1). Compactness is an expressed design goal of the art, so shrinking to the claimed limits is "use of a known technique to improve similar devices in the same way" (MPEP § 2143(C)).

Claim 6 (manifold through hole < 0.1 in). The patent's own specification sets the through-hole range at ≤ 0.2 in (preferred ≤ 0.15, more preferred ≤ 0.125, and then "0.10 inches or less"), i.e., a continuous design range. The art's orifices are one to two orders of magnitude smaller (0.0009 in. sample, 0.0045 in. dilution in US 5,458,010), and US 5,178,022 uses "a Lee Visco Jet orifice of stainless steel construction, consisting of a 0.187 inches in diameter and between 0.66 and 0.72 inches of length" precisely to get a large housing with a small effective restriction. Selecting a sub-0.1 in. passage between two taps of a manifold is optimization of a result-effective variable (flow restriction → dilution ratio and vacuum level) and, under MPEP § 2144.05, "[o]bviousness … is not avoided by a recitation of a range that is within or overlaps a range disclosed in the prior art."

Claim 8 (pipe coupling). US 5,458,010 mounts the heated chamber "engaging mounting nipple 68 which protrudes from wall 70 of stack 47"; Lear Siegler has support flange 28 and threaded probe support 86. A pipe coupling is an ordinary mechanical joiner (and is described as such in the '303's own specification at element 190).

Claim 9 (pipe coupling → probe stinger; probe end inside a stack). Every primary reference mounts the probe through the stack wall and, in US 5,458,010, the assembly "can be moved within the flue to control the location within a stack that the probe end assembly takes a gas sample." A stinger/ball-valve-type insertion mount is standard CEMS hardware; US 5,178,022's "probe body including the eductor is inserted within an aluminum heater body" and its "heated enclosure 80" outside the stack mirror the '303's FIG. 7 arrangement almost exactly.

---

6. A reference the file should not overlook

US 5,178,022 / EP 0 530 684 A1, "Inertial filtration external dilution probe" appears on the '303 page in the "Similar Documents" section (not the "Citations" list). Its disclosure is unusually on-point for claims 2, 3, 6, 8, 9: a dilution probe located outside the stack; coarse filter 46 plus fine filter 54 in series; a critical orifice 56 downstream; an eductor 60 providing both the vacuum and the dilution air; a heated aluminum body "regulat[ing] the temperature of the probe body to approximately 300 °F"; calibration gas that "follows the same flow path as stack gas"; a probe flow "of 10‑300 ml per minute"; and analyzers for "SO₂, Cl₂, ClO₂, NH₃, HF, CO, CO₂, O₂, HCl, TRS, total sulfur, NO and NO₂." That is a near-complete structural and motivational blueprint for claims 2–3, 6–9 and for the specification's acid-gas analyte list. Sources: https://patents.google.com/patent/EP0530684A1/en; https://patents.justia.com/patent/[5178022](/patent/5178022). Caveat: it is not among the 17 face-cited references, so a validity opinion relying on it should verify its availability as prior art (filing/priority date relative to 2019‑01‑21) and confirm it was considered.

---

7. Where the obviousness case is weakest

1. The "helical heating element within the internal cavity of the outer probe housing" limitation (claim 1, element 2). US 5,039,322's heater coil sits in the annular space between the inner tube and the outer shell, and the annular space contains heat insulation 21. If the outer shell's liquid-cooled double-wall character is read as a structural divergence — Voest‑Alpine is a cement/steel reaction-vessel probe, not a flue-gas CEMS probe — a patent owner will argue the POSA would not have looked to it and that it teaches away from an outer housing that is merely a housing rather than a heat sink. This is an argument about motivation, not about capability, and it is answerable because (i) the problem addressed (dew-point condensation in a heated extractive probe) is identical, (ii) both are G01N 1/22, and (iii) claim 1 does not exclude a cooled outer housing. But it is the single most contestable point, and it is the point on which the granted claims most likely survived.
2. "Calibration tee." US 4,974,455 discloses calibration passageways rather than a tee-labeled fitting. A patent owner may argue "tee" imports a specific unitary three-port body inside the inner housing. The counter is that "tee" is a label for a conventional three-port fitting — a classic example of "[t]he combination of familiar elements according to known methods" under KSR — and that nothing in claim 1 or the specification defines the tee's geometry beyond having three ports. The '303's own specification describes the tee only by function ("a first port for receiving a sample gas, a second port for receiving a calibration gas, and a third port"), reinforcing that this is a functional, conventional fitting.
3. Prosecution history is unknown. Because I could not retrieve the 2022‑01‑27 non-final action or the 2022‑03‑13 response, I cannot say what the examiner actually rejected or what argument carried the day. My §3 combination is a reconstruction, and the patent owner may have already distinguished these exact references on a basis I cannot see. This is a material limitation of the analysis.
4. Title-only references. GB 966,064; GB 1,336,253; US 4,657,744; US 5,184,501; US 6,200,819; WO 2001/084111; US 6,546,812; JP 2006‑145341; KR 100907875; CN 106,527,544; JPH06123683; US 3,817,100 — I have only bibliographic data/abstracts for these. Any mapping I gave for them is provisional and should be confirmed against full text before being relied on in a written opinion. Notably, CN 106,527,544 ("Temperature, humidity, flow, pressure controllable sonic nozzle gas experimental device," Tianjin University) is directly relevant to the "temperature- and pressure-regulated … nozzle" limitations and deserves a full-text pull.

---

8. Secondary considerations and the nexus problem

The '303's stated advance (Background) is that "current extractive systems fail to accurately measure what are known as 'sticky' pollutants (including, e.g., HCN) that adhere to various internal ducts or piping." Three observations:

• No claim recites HCN, any specific analyte, any material of construction, or any surface-passivation feature. The specification's response to the "sticky pollutant" problem — all-metal 316SS construction, heating above 200/250 °F — is either unclaimed (materials) or claimed only generically (a helical heating element with no claimed temperature). Under In re Kao / MPEP § 716.01(c), an asserted advantage with no nexus to the claimed subject matter cannot rebut prima facie obviousness.
• The claimed numerical limits are the least probative of nexus. Claim 6's <0.1 in. through-hole and claims 4–5's dimensions are exactly the kind of "result-effective variable" optimization that MPEP § 2144.05 treats as obvious, and no unexpected-result data appears anywhere in the specification.
• The "low-pressure, low-flow" characterization is fully met by the prior art. US 5,458,010's 4.2 cc/min sample flow and 0.15 atm transport vacuum bracket the specification's "<100 cc/min" and "≤ 0.25 atm" (nearly "≤ 0.1 atm"). There is no gap here for the patent owner to occupy.

Absent evidence of commercial success, licensing, copying, or long-felt need with a nexus — none of which appears in the record in hand — there is no secondary-consideration rebuttal on the current record.

---

9. Bottom line

• The §103 case against claims 1 and 7 is strong but not airtight. The best combination is US 5,039,322 (which alone discloses the inner-tube-inside-coiled-resistance-heater-inside-outer-shell architecture claimed in elements (a)–(c)) + US 5,458,010 (which alone discloses the dual-nozzle/manifold dilution core and every operating parameter the '303's specification recites: 1:1–250:1 dilution, 250 °F stabilization, 0.15 atm vacuum, 4.2 cc/min flow, bottled N₂/air, sub‑30 °F dew-point target, and sub‑0.1″ orifices) + US 4,974,455 (calibration line/tee function, coarse filter end cap, probe-in-stack mounting, analyzer duct). The motivation is supplied by the references themselves — the same EPA/CEMS compliance problem, the same acid-gas/dew-point problem, and US 5,458,010's express criticism of the traditional extractive and venturi dilution approaches.
• Dependent claims 2–6 and 8–9 are, on this record, weaker than claims 1 and 7. Each maps to conventional, well-motivated additions or to routine optimization (including the In re Aller/In re Peterson range cases), and US 5,178,022 — found in the page's "Similar Documents," not its citation list — supplies claim-3's motivation almost verbatim.
• The two limitations a patent owner will defend are the "helical heating element within the internal cavity" and the "calibration tee within the inner probe housing." Both have defensible-but-not-conclusive answers (Voest‑Alpine's heating coil; a tee being a conventional three-port fitting). If the 2022 prosecution turned on either of these, that is where the file should be read most carefully.
• Confidence: high on the US 5,458,010 mapping (full text reviewed); high on the US 5,039,322 and US 4,974,455 mappings (claims/specification text reviewed); low-to-moderate on all title-only references, and no confidence at all about the actual 2022 prosecution record, which I could not retrieve and which any formal opinion must obtain from USPTO PatentCenter/Public PAIR for application 16/744,451.

One process note for the file: the current-task header states the date as April 26, 2026, while the record fetch date is 2026‑09‑24. Nothing in this analysis turns on the date, but the discrepancy is flagged as required rather than silently reconciled.