US 6402613

I'll verify the patent details and check for any litigation/docket activity before summarizing.

Let me check for any litigation or assignment chain activity involving the patent's owners.

US 6,402,613 B1 — Verification and Summary

Note on identifier discipline: I searched on the literal string "6402613." Several unrelated results carry that numeral string, and I am not treating any of them as this patent:

• Brazilian industrial design registration DI 6402613-2 (Carlos Augusto Olivo) — different register/jurisdiction.
• Japanese patent JP 6402613 B2 (Bridgestone Sports, golf balls) — a JP number, not US.
• A bone-screw catalog SKU "6402613" in a hospital chargemaster PDF.

The US patent below is confirmed against the authoritative full text at patents.google.com/patent/US6402613B1 and mirrored at FreePatentsOnline.

Bibliographic data

Abstract (as issued)

A portable environmental control system for evacuating particulate laden, toxic, and explosive gasses from an interior space includes a flexible partition for erection at the interior space, and a first section of flexible duct connected to the partition and to an electric motor driven blower unit having an explosion proof ducted fan. A second section of duct is connected to the blower unit and may be connected to a filter unit mountable in a window of an interior room or to a collapsible plenum having plural filter units mounted therein for treating and returning air evacuated from the space back into the space. The blower unit may be placed within a space having a high concentration of explosive gasses for evacuating the gasses by way of an elongated duct section connected to an elevating mechanism to discharge gasses out of doors above ground level.

Independent claims in plain language

Claim 1 — the basic system (non-safety-specific framing). A portable system for pulling toxic, particle-laden, or explosive gases out of a space, made of four cooperating parts:

1. a first flexible duct whose intake end sits in (or draws from) the space;
2. a motor-driven blower unit — a housing with an inlet port, a discharge port, and a flow duct between them, where the inlet is hooked to the far end of the first duct, and a propulsion fan moves the gases through the first duct and through the housing's flow duct;
3. a second flexible duct attached to the blower's discharge port; and
4. at least one filter unit at the far end of that second duct, to receive the evacuated gases and treat them to reduce the hazard.

Claim 20 — the integrated, explosion-safety-oriented combination. A narrower/more fully specified independent claim requiring all of the following together:

• a flexible partition member that delimits at least part of the space and has a port in it (the doorway curtain of FIG. 1 or the tent of FIG. 9);
• a first flexible duct connected to that partition port;
• a motor-driven blower unit whose housing is made of substantially non-sparking material, with inlet/discharge ports and a flow duct between them, and whose propulsion fan is driven by an electric motor through mechanical drive means with the motor and drive isolated from contact with the evacuated gases;
• conductor connection means including an explosion-proof junction box, plus a power cord connectable at that junction box;
• a second flexible duct on the discharge port;
• a portable plenum with a port for receiving the second duct; and
• a plurality of filter units mounted inside the plenum, discharging air substantially free of particulates and/or toxic or explosive gases.

The remaining 23 claims are all dependent: claims 2–19 build on claim 1 (partition/curtain vs. tent, indirect drive isolation, wheels, explosion-proof junction box plus dual power cords, non-sparking housing with impact bumpers, filter panel stacks, collapsible/plenum-mounted filter units, and the wheeled multi-stage filter cabinet); claims 21–25 build on claim 20 (wheels, cord storage, second power cord, filter media types, flexible-bag plenum).

Commercial/technical context disclosed

The spec frames the invention against prior art limitations it says were unresolved: direct-drive blowers above ~800 CFM send fumes through the motor and are not hazardous-condition rated; HEPA-based systems cap around 500 CFM; systems above 1000 CFM typically demand a 220–240 V dryer/washer outlet that apartments, hotels, silos, and shops often lack. The disclosed blower is a UL hazardous-conditions-rated indirect (belt) drive axial fan in a duct (a "TUBEAXIAL" type from Dayton Electric), 12–14 inch ducts, ~1,600 CFM unfiltered / ~1,000 CFM filtered, NEC-style SO cord in flame/abrasion-resistant sleeving (Goodyear "Gorilla" rubber), Appleton "U-LINE" sealed receptacles/plugs, and a portability story (casters, ~5–6 ft square knock-down plenum, fabric-reinforced-vinyl bag plenum, 15–20 ft elevated discharge using a Bogen Cine "AVENGER" lighting-grip stand). Cited art includes the Abatement Technologies portable-filtration-unit family (US 5,069,691; 5,230,723; 5,433,763; 5,588,985), Riutta's bag-like plenum chamber (US 5,312,465), Enviro-Air's particulate abatement system (US 5,004,483), Daudelin's portable collapsible fume extractor (US 2,348,455), and Simon Roofing's noxious-fume removal system (US 5,873,919).

Litigation / docket check (CAFC and district)

I found no litigation, IPR/PGR, or Federal Circuit docket activity for US 6,402,613. Searches targeting litigation involving the patent number returned only the unrelated Brazilian design registration, the Japanese golf-ball patent, and a bone-screw SKU (above). A search of the patent owner names surfaced only a non-litigation SBA/SBDC case study describing the Teagles' Enviroblower business (David Teagle invented the system; company formed 2000; Teagle incorporated Teagle Patent Holding Co. and American Ventilation Equipment) — SBA story PDF. Combined with the recorded "Expired – Fee Related" status and 2021-02-21 anticipated expiration, there is no evidence of an active enforcement campaign.

Uncertainties and caveats

• Litigation coverage is not exhaustive. I cannot access PACER or the CAFC's own docket search directly; my conclusion rests on open-web search. A party-level PACER/CAFC query would be needed for a definitive negative.
• Assignment history beyond the register. The chain shown is Teagle → Enviroblower (2002-04-22) → Teagle Patent Holding (2002-12-09, change of name). Google states the assignee list "may be inaccurate" and disclaims legal analysis; the current owner of record should be confirmed via USPTO Assignment Search if it matters.
• Cited-by count is reported inconsistently on the source page ("Cited By (66)" versus a separate 99-row table). I am relaying both figures literally rather than reconciling them.
• Internal drafting inconsistencies in the spec (noted, not corrected): the fan is called "61" in one passage and "62" in another; reference numeral 82 labels both a plenum top wall and the alternate bag plenum; 84 labels both a bottom wall and the bag plenum's top wall; and 137 labels both guide vanes and a tent flap. These are spec-level editorial matters and do not change claim scope.
• Claim scope caveat: claims 1 and 20 use functional/generic language ("mechanical drive means," "conductor connections means"), and claim 20 recites gas-phase filtration alongside a partition, isolated-drive blower, explosion-proof junction box, and plenum-mounted filter bank — a combination narrow enough that infringement analysis would turn on the plenum-plus-multiple-internal-filter-units and isolation limitations, not on the bare ducting arrangement of claim 1.

I'll run targeted searches for litigation records on this patent number across patent-litigation portals, docket sources, and the owner names.

Let me run additional targeted searches on the owner names and on PTAB/ITC activity.

Litigation check for US Patent 6,402,613

Bottom line: I found no known litigation involving US 6,402,613 — no district court case, no ITC investigation, no PTAB proceeding (IPR/PGR/CBM), and no Federal Circuit appeal.

This confirms (rather than contradicts) the litigation conclusion already reached in the earlier "Patent summary" section of this analysis. I flag one non-substantive inconsistency: that section's header dated the work with one date, and the task instruction now states "Current Date: April 26, 2026," while the tool environment reports 2026-09-28. Nothing about the substance of the finding turns on this.

What I searched and what came back

Literal-number discipline (results I am NOT treating as this patent)

Consistent with the earlier section, the numeral string "6402613" surfaces a cluster of unrelated records, none of which is US 6,402,613 B1:

• DI 6402613-2 — a Brazilian desenho industrial (industrial design) registration to Carlos Augusto Olivo (BR/SC), published 19/10/2004 in INPI's Revista da Propriedade Industrial (PATENTES 2221). Different register, different jurisdiction, different subject matter.
• JP 6402613 B2 — Japanese Patent No. 6402613, patentee Bridgestone Sports K.K. (golf balls). A JP number, not a US patent.
• "6402613 BONE SCREW T10 FULL THREAD 3.5mm/L34mm C1713" — a hospital chargemaster/catalog SKU appearing in a BHSH supply report PDF.
• Various unrelated AIA/PTAB, EDTX, UPC, and FWK Holdings v. Takeda documents that merely co-occur with the digits.

Case-by-case table

There are no cases to tabulate. For completeness, in the requested format:

Corroborating circumstantial evidence of no enforcement campaign

• Prosecution/register history on the authoritative source (patents.google.com/patent/US6402613B1) records only the ordinary chain: filed 2001-02-21 by Enviroblower LLC; issued 2002-06-11; assignment from Teagle to Enviroblower recorded 2002-04-22; change of name to Teagle Patent Holding, L.L.C. recorded 2002-12-09. No security interests, no recordal of judgment, no reissue/reexam entries.
• Legal status is "Expired – Fee Related," with anticipated expiration 2021-02-21. A patent that lapsed for non-payment of maintenance fees is inconsistent with an active assertion program.
• The only owner-related web hit is a non-litigation SBA/Small Business Development Center case study describing the Teagles' business formation — not a lawsuit.
• The "Cited By" tables on the source page (reported as 66 and, in a separate table, 99 rows) are forward citations by later patents — these are prior-art citations, not evidence of litigation.

Caveats (stated so the conclusion is not overstated)

1. Coverage is open-web only. I cannot query PACER, the CAFC docket, or Docket Navigator's full-text dockets directly from this environment. A party-level PACER/CAFC docket search on "Teagle Patent Holding," "Enviroblower," and "American Ventilation Equipment," and a Docket Alarm/Unified portal query on the patent number, would be required for a truly definitive negative.
2. Pre-2002 dockets may be poorly indexed. If any infringement suit was filed in 2002–2005 (the patent's active window before lapse), older paper-era filings could be absent from free full-text indexes.
3. A negative finding is not proof of absence. I state explicitly: I do not know of any litigation with high confidence grounded in a complete docket database; my finding rests on the searches described above.
4. Assignment/ownership verification is separate. Whether Teagle Patent Holding LLC remains the owner of record should be confirmed via USPTO Assignment Search if it matters for a clearance or enforcement opinion.

Proceedings overview

Total AIA trial proceedings on US 6,402,613: zero — the canonical "PTAB proceedings on file" block from the USPTO Open Data Portal returns no IPR, PGR, or CBM for this patent, and independent web searching surfaced no petition, institution decision, Final Written Decision, or appeal bearing this patent number (details and verification trail below). With no pending, instituted, settled, or decided proceeding, the defensive posture is neither "hardened by surviving IPRs" nor "already dead" — it is untested at the PTAB, and the reason is almost certainly commercial rather than legal: the patent expired on 2021-02-21 for failure to pay maintenance fees, so there was never a live royalty stream worth attacking.

Proceedings

None — no AIA trial proceeding exists for US 6,402,613

• Type: N/A (no IPR, no PGR, no CBM, no derivation)
• Filed: N/A
• Status: No proceeding on file (USPTO ODP structured block: empty). No counterpart on PTAB E2E or on CourtListener.
• Judge panel: N/A
• Petition grounds: N/A
• Institution decision: N/A
• Final Written Decision: N/A
• Settlement / termination: N/A
• Appeal: N/A
• Defensive value: A defendant cannot lean on an invalidating FWD, but also faces no § 315(e)(2) estoppel and no IPR-driven narrowing — every invalidity theory, including ones a petitioner would have "reasonably could have raised," remains fully available in district court or in a declaratory-judgment posture.

Verification trail and identifier discipline. Searches on the literal string "6402613" return several look-alikes that I am not treating as this patent and that generated the only "hits":

No returned document names Teagle, Teagle Patent Holding, or Enviroblower as a party. The only Teagle-related result is a non-litigation SBA/SBDC case study describing the Enviroblower business — SBA story PDF — which corroborates the ownership chain in the earlier section (David Teagle; Teagle Patent Holding Co.; American Ventilation Equipment) and shows no enforcement posture.

Coverage caveats I will not paper over:

• I could not reach PTAB E2E or PACER directly from this environment; the negative rests on the ODP structured block plus open-web search. A party-level PACER/PTAB E2E query is the only definitive confirmation.
• "No AIA trial proceedings" ≠ "no post-issuance proceedings at all." Ex parte reexamination, reissue, and (in older patents) inter partes reexamination are not captured by the AIA-trial structured data. I did not verify reexamination or reissue history for this patent, and I would not represent that it has none. That gap should be closed before any FTO opinion relies on this report.
• I have no docket evidence of any litigation involving this patent. Combined with the 2021-02-21 fee-related expiration and the current assignee of record (Teagle Patent Holding LLC), the practical inference is that the patent was never asserted at scale.

Strategic summary

Claim status: everything is UNTESTED. There is no FWD, so no claim of US 6,402,613 has been canceled, confirmed, or construed by the Board. All 25 claims stand as issued — independent claims 1 and 20, and dependent claims 2–19 and 21–25. If a demand letter or complaint cites claims 1–5, claims 1–5 are alive in the literal sense; they have simply never been stress-tested. The earlier-section claim-scope note remains the right lens: claim 20 is the narrow, integrated combination (flexible partition + non-sparking housing + mechanically driven fan isolated from the gas stream + explosion-proof junction box + portable plenum + multiple filter units inside the plenum), and that plenum-plus-internal-filter-bank limitation is where an invalidity or non-infringement attack would concentrate, not on the bare ducting of claim 1.

Estoppel: clean slate, but also no leverage. Because no IPR/PGR was ever instituted against this patent, there is no § 315(e)(2) estoppel binding anyone, and no petitioner/privy to worry about. Conversely, a defendant gets no benefit from an earlier challenger's work — no FWD to quote, no cancellation to point at, no Board claim construction to borrow. Two independent constraints do apply to a new IPR, though: § 315(b)'s one-year bar runs from service of a complaint alleging infringement, and § 315(a)'s bar applies if the challenger filed a DJ action first. Given the 2021-02-21 expiration and the assignee's apparent dormancy, spending IPR fees to challenge an expired patent is usually a poor trade (review of an expired patent is legally permissible, but claim-amendment options are foreclosed and there is no prospective injunctive value to negate — I flag that as general practice rather than a verified citation to authority in this record).

Pattern signals: none, on every axis. No repeat petitioner (there is no petitioner at all). No PTAB appeal activity by the patent owner. No defensive aggregator — nothing in the record shows Unified Patents, RPX, or any similar entity touching this patent. The patent's high forward-citation count (reportedly 66–99 citing documents, per the earlier section's note on the inconsistent figures) shows it is technically relevant in the portable-filtration/blower field, but that citation traffic never converted into an inter partes challenge.

Recommended next steps

1. Treat the absence as the finding — but state it precisely. For a client facing assertion today, the correct sentence is: "There is no PTAB proceeding on US 6,402,613; no claim has been canceled, confirmed, or construed by the Board." Do not say the patent "has never been challenged," because reexamination/reissue history was not verified here.
2. Close the two data gaps before relying on this. (a) Run a party-level PTAB E2E search (ptacts.uspto.gov) and PACER check on "Teagle Patent Holding LLC," "Teagle," "Enviroblower," and "American Ventilation Equipment"; (b) pull the file wrapper for 09/790,178 via USPTO PatentCenter to confirm no ex parte reexamination, reissue, or certificate of correction affecting claim scope.
3. Lead with the expiration, not with invalidity. Anticipated expiration 2021-02-21, status Expired – Fee Related (per the source page). Any damages theory is confined to pre-expiration infringement within the § 286 six-year lookback, which today reaches back to 2020-09-28. That is a short, narrow window; expect it to collapse the economics of any assertion.
4. Preserve the invalidity case anyway. Because there is no estoppel and no prior FWD, build the § 102/§ 103 record from scratch. The cited-art table already gives a starting set of primary references in the same field — notably Abatement Technologies' portable filtration unit family (US 5,069,691; 5,230,723; 5,433,763; US 5,588,985), Riutta's bag-like plenum chamber (US 5,312,465, directly relevant to claims 12–15 and 25), Enviro-Air's particulate abatement system (US 5,004,483), Daudelin's portable collapsible fume extractor (US 2,348,455), and Simon Roofing's noxious-fume removal system (US 5,873,919). Claim 20's plenum-with-multiple-internal-filter-units plus isolated mechanical drive is the limitation to map; claim 1 is the broadest target.
5. If an active proceeding ever appears (none does today), the statutory clock is fixed: institution decision within 6 months of the patent owner's preliminary response, and FWD within 12 months of institution under § 316(a)(11), appealable only to the Federal Circuit under § 141(c). I found no such proceeding to track.

Bottom line: no PTAB proceeding exists on US 6,402,613 — no institution, no FWD, no appeal, no settlement. The patent's claims are all intact but wholly untested, and the 2021 fee-related expiration means the more useful defensive fact for a defendant is the date, not the Board's docket.

I'll research the assignment record for this patent, starting with the USPTO Assignment Center and related sources.

Inventors

Unusual patterns: None of the classic red flags. There is no multi-inventor team to disperse, no evidence any inventor left a corporate assignee within 12 months of filing, and the inventor did not exit the chain — he remained the principal of both the operating company and the eventual IP-holding entity. The SBA/SBDC case study ("One Opportunity Leads to Another," SBA story PDF) confirms Teagle "incorporated and owns Teagle Patent Holding Co., and American Ventilation Equipment," while Enviroblower, Inc. itself was reorganized as a woman/minority-owned entity with Torrez as sole owner (July 2002 onward). In other words, the late-2002 asset split ran operating company → one spouse, patent holding entity → the other, not inventors fleeing a failing assignee.

Original assignee

Enviroblower, L.L.C. (rendered "ENVIROBLOWER LLC" on the face of the patent and in Google Patents' "Original Assignee" field; the 2002-04-22 record spells it "ENVIROBLOWER, L.L.C.").

• Line of business: portable hazardous-conditions ventilation/blower equipment for evacuating VOCs and combustible gases from confined spaces — i.e., the commercial embodiment is the very system claimed.
• Did it ship product? Yes, on the evidence available. The SBA case study describes Enviroblower as a company "formed to develop and sell the ventilation system," and recounts distribution negotiations with Olmstead-Kirk to add "the Enviroblower to their equipment list." That is product commercialization, not pure licensing.
• Current status: Not clearly determinable from the sources I could reach. The operating business was restructured in 2002 (Enviroblower, Inc., woman/minority-owned, Torrez as sole owner) and the patent was meanwhile parked in Teagle's holding entity. No bankruptcy, dissolution, or acquisition record surfaced. What is documented is the patent-side outcome: the patent lapsed Expired – Fee Related with an anticipated expiration of 2021-02-21, i.e., the maintenance-fee clock was allowed to run out rather than the patent being asserted or sold.

Assignment timeline

⚠️ Data-availability caveat (important): The USPTO Assignment Center (assignmentcenter.uspto.gov; mirrored/searchable at assignment.uspto.gov/patent) was not reachable from this session, and no accessible secondary source surfaced reel/frame numbers, execution dates, or the correspondent of record for this patent. Google Patents' legal-events mirror shows two post-filing records, but it publishes only the record type, assignor, assignee, and recording date — not the reel/frame or the recording attorney. I am not fabricating reel/frame or correspondent values to fill those cells. The fields below are therefore marked "not retrieved," and signal 3 (repeat correspondent) cannot be scored as a result. Verification requires a direct patent-number lookup in Assignment Center.

• Execution date not shown / recorded 2002-04-22 — Reel not retrieved / Frame not retrieved

  • Conveyance: Assignment of assignors' interest (inventor → company)
  • Assignor: Teagle, David B. (sole inventor)
  • Assignee: Enviroblower, L.L.C.
  • Correspondent: not retrieved (Assignment Center UI needed; no search result surfaced the recording attorney)
  • Context: acquisition — the inventor's pre-issuance assignment of the application to his own operating company, recorded ~7 weeks before the 2002-06-11 grant.

• Execution date not shown / recorded 2002-12-09 — Reel not retrieved / Frame not retrieved

  • Conveyance: Change of name (NOT a transfer of ownership)
  • Assignor: Enviroblower, L.L.C.
  • Assignee: Teagle Patent Holding, L.L.C.
  • Correspondent: not retrieved
  • Context: change of name only / internal reorg — the underlying owner is unchanged; the operating entity's name was changed to a patent-holding name. This is the record that makes "Teagle Patent Holding LLC" the listed current assignee. Because it is a change of name rather than an assignment, there is no third party that acquired the patent at this link.

No third link exists. There is no recorded sale to an unrelated acquirer, no security agreement, no license recordation, and no transfer to any entity on a public NPE list — again subject to the caveat that I could not query Assignment Center directly for any later records that Google's mirror might omit.

Timeline diagram

timeline
    title Ownership of US 6402613
    2000 : Enviroblower founded by the Teagles
    2001 : Application filed 2001-02-21
    2002 : Assigned to Enviroblower LLC recorded 2002-04-22
         : Patent issued 2002-06-11
         : Change of name to Teagle Patent Holding recorded 2002-12-09
    2021 : Anticipated expiration 2021-02-21

NPE / troll-pattern signals

Verdict

Insufficient data — effectively "only the original assignment," with no post-issuance arm's-length transfer and no assertion activity.

The entire recorded chain is two touches: the inventor's pre-issuance assignment to his own operating company (recorded 2002-04-22, Enviroblower, L.L.C.) followed by a change of name only to Teagle Patent Holding, L.L.C. (recorded 2002-12-09) — i.e., the same owner throughout, confirmed by the SBA account of the 2002 Teagle/Torrez business split. No NPE in the chain, no suit, no fire sale, and the patent simply lapsed Expired – Fee Related on the 2021-02-21 anticipated-expiration date. Occupying an intermediate state — a genuine IP-holding entity exists, but it is the inventor's own and never asserted — this is a non-asserting, owner-retained patent, and the honest verdict under the required taxonomy is Insufficient data rather than an affirmative NPE classification.

Verification links: Assignment Center — https://assignmentcenter.uspto.gov/ ; indexed view — https://assignment.uspto.gov/patent/index.html (search patent number 6402613 to obtain the reel/frame and correspondent cells that were not retrievable here). Google Patents legal events — https://patents.google.com/patent/[US6402613B1](/patent/US6402613B1)/en .

Two residual gaps to close with a live Assignment Center query (do not treat the above as exhaustive without it): (a) reel/frame and recording attorney for both 2002 records — needed to score signal 3; and (b) confirmation that no third, later record (e.g., a security agreement or a transfer to an entity Google's mirror omits) exists.

I'll verify the patent on USPTO and research each cited reference before analyzing anticipation.

Let me verify the USPTO record and gather details on the remaining cited references.

USPTO record check for 6402613

Literal-identifier discipline applied. I searched the exact string "6402613" and filtered to the US register. The record confirmed for US 6,402,613 B1 is:

• Application 09/790,178; filed/priority 2001-02-21; granted 2002-06-11; inventor David B. Teagle; original assignee Enviroblower LLC, later Teagle Patent Holding, L.L.C.; status Expired – Fee Related (anticipated expiration 2021-02-21). Confirmed at patents.google.com/patent/US6402613B1 and FreePatentsOnline; the USPTO PatentCenter/Assignment links on that record are the authoritative register sources.

I did not substitute any similar-numbered document. Results for the numeral string "6402613" that are not this patent (Brazilian design DI 6402613-2, Japanese JP 6402613 B2, a hospital SKU) are excluded, consistent with the earlier section.

One framing correction to build on: the earlier section called the citation count "21–23." Precisely, the page shows a 21-row unique-reference table and a 23-row table that adds two additional entries — US 5,069,691 B1 and US 5,069,691 B2 — which are the defensive-publication/certificate variants of the same Abatement patent (US 5,069,691 A). So the substantive prior art is 21 unique references (23 entries). I analyze all 21 below. This is 23 entries, not a discrepancy in my prior count.

Critical statutory note (pre-AIA §102, since this is a 2001 filing): every cited reference issued before 2000-02-21. The latest two are US 5,873,919 (1999-02-23) and US 5,853,441 (1998-12-29). Therefore all 21 references qualify as §102(b) statutory bars, and none is a §102(e) "secret prior art" reference. That matters: these citations were available to the examiner as full anticipation art, not merely §102(a) knowledge.

The §102 reality check (read this before the per-reference table)

True §102 anticipation requires one reference disclosing every element of a claim, arranged as claimed. Claims 1 and 20 are demanding combinations — claim 1 requires the specific chain flexible first duct → motor-driven blower with an internal flow duct and propulsion fan → flexible second duct → filter unit; claim 20 adds non-sparking housing, mechanically-driven fan with the motor/drive isolated from the gas stream, explosion-proof junction box + power cord, and a portable plenum containing a plurality of filter units.

My assessment: no single cited reference discloses all elements of claim 1 or claim 20. The citations are best understood as (i) background showing the general state of portable fume/particulate filtration, and (ii) §103 combination art for individual limitations. The genuinely "closest" references are US 5,312,465 (Riutta) for the flexible-bag-plenum and belt-drive features, the Abatement family (US 5,069,691 et al.) for the multi-filter portable cabinet, and US 5,004,483 (Enviro-Air) whose very title — "Particulate abatement and environmental control system" — most nearly tracks claim 1.

Caveat on completeness: I could retrieve full text for the Abatement family, Riutta, and (partially) Daudelin, but my tool budget ran out before I could pull the full text/claims of US 5,004,483; 5,873,919; 5,853,441; 5,417,729; 5,281,246; 4,512,245; 4,446,861; 4,905,578; 4,932,988; 4,163,650; 2,747,201; and 667,149. For those, my descriptions rest on the patent's own citation table (number, inventor/assignee, title, dates) plus general knowledge, and I flag them as unverified against the reference's full text. A definitive element-by-element anticipation chart requires pulling each reference's specification and claims.

Per-reference analysis (21 unique references, in citation-table order)

Legend for the §102 verdict: [NO-§102] = cannot anticipate a claim in full; relevant only as §103 combination art. [PARTIAL] = discloses the added limitation of a dependent claim but not the full claim (parent + dependent). [POSSIBLE] = plausible full-claim exposure, needing text confirmation.

Group A — Portable particulate/fume filtration units (the strongest art)

Group B — Local-exhaust / source-capture fume devices

Group C — Room/area contamination control, partitions and ventilation

Synthesis: most relevant prior art for US 6,402,613

1. US 5,312,465 (Riutta) — most relevant to the structural heart of the disclosure (a belt/sheave mechanically-driven fan and a flexible bag plenum), and therefore the reference an examiner or challenger would anchor on for claim 5 (mechanical drive means) and claims 14/15 (flexible-bag plenum). Its express statement that the plenum is a diffuser, not a filter is the distinction that saves claim 12's "plurality of filter units mounted in the interior of said plenum."
2. US 5,004,483 (Enviro-Air Control) — title-level match to "environmental control system"; the most likely claim 1 anticipation candidate. Must pull full text to test whether it teaches the two-flexible-duct + in-housing-flow-duct blower chain.
3. Abatement family (US 5,069,691 A/B1/B2; 5,230,723; 5,433,763; 5,588,985) — the most relevant art for claims 11, 18, 19 (multi-stage filter cabinet on wheels) and portability. A §103 combination of Abatement + Riutta would target the plenum/filter-cabinet dependent claims.
4. US 2,348,455 (Daudelin) and FR 2,675,717 (Lateste) — the examiner's citations closest to the partition/tent concept of claims 2–4.
5. US 4,512,245 (Adsorbent Products) and US 5,139,546 (Novobilski) — the citations closest to the gas-phase/adsorbent filter element of claim 11.

Bottom line on §102: On the available record, no cited reference anticipates claims 1 or 20. The citations support, at most, §103 obviousness positions against the dependent claims (esp. 5, 11, 14, 15, 18, 19), built from Riutta + the Abatement family + a source-capture reference. Claims 12, 13, 20's "plurality of filter units mounted in the plenum," claim 7's "explosion-proof junction box," and claim 10's "force-absorbing bumper" remain the most defensible differentiators.

To finalize: I could not, within this session, retrieve the full specifications/claims for references #1 (5,004,483), #7 (5,281,246), #8 (4,163,650), #9 (4,932,988), #10 (5,873,919), #11 (5,853,441), #12 (5,417,729), #17 (4,446,861), #20 (FR 2,675,717), and #21 (667,149). Those verdicts are flagged as unverified and should be confirmed against full text before being relied on as a definitive anticipation chart.

I'll ground the key prior-art references from the patent's citation tables before building the §103 analysis.

Obviousness Analysis — US 6,402,613 B1 under 35 U.S.C. § 103

0. Scope, framework, and a flagged inconsistency

Governing law. Application US 09/790,178 was filed 2001-02-21 and issued 2002-06-11, with no earlier priority claim. It therefore sits squarely under pre-AIA § 103(a). The analysis uses the Graham v. John Deere factors (scope/content of the prior art; differences between the claims and the prior art; level of ordinary skill; secondary considerations), construed through KSR Int'l v. Teleflex — i.e., a flexible motivation inquiry permitting "combination of familiar elements according to known methods," predictable results, and design incentives/market pressure, not a rigid teaching–suggestion–motivation test.

Date conflict (flagged). The task header states "Current Date: April 26, 2026," while the authoritative patent text header in this thread states the fetch date as 2026-09-28. This does not affect the analysis (all relevant art predates 2001-02-21 by years/decades), but the two dates are inconsistent and I am not silently reconciling them.

Prior-art universe used. Per instruction, I use the "Prior Art" section of the page — i.e., the 21–23 references in the "Patent Citations" table (the examiner-considered art). I treat the "Cited By (66)" / "Cited By (99)" tables as not generally available as § 102/103 prior art, because their priority dates are overwhelmingly later than 2001-02-21. One exception worth flagging: US 2005/0013711 A1 (Goyetche, "Exhaust fan") carries a priority date of 2000-08-16, which does predate the filing; its content and its § 102(e) availability would need verification before use, and I have not verified it.

Verification status of cited references (important for honesty about confidence):

1. Person of ordinary skill in the art (PHOSITA)

A PHOSITA here is an industrial ventilation / air-filtration engineer or senior field technician with roughly 2–4 years' experience designing or specifying portable air-moving and filtration equipment for construction, abatement, and industrial hygiene applications, and with working familiarity with:

• axial vs. centrifugal fan selection and direct (motor-on-shaft) vs. indirect (belt/sheave) drive practice;
• hazardous-location (classified-area) practice — NFPA 70/NEC Article 500–501, explosion-proof junction boxes and sealed receptacles/plugs, UL 705-type listings, non-sparking construction and grounding/bonding;
• flexible duct sizing and static-pressure losses (hence the patent's own 12–14 in. duct and 1,000–1,600 CFM figures);
• multi-stage filtration trains (impingement/pre-filter → bag/electrostatic → carbon or chemisorbent → HEPA) and activated-carbon/permanganate gas-phase media.

This is a mature, crowded, heavily catalog-driven art. That matters: in such arts, KSR's "known options" and "market demand" rationales are at their strongest, and the patent's own specification confirms the art's maturity by naming off-the-shelf components (below).

2. The prior-art landscape (the "Prior Art" section, clustered by function)

Cluster A — Portable, wheeled, multi-stage filtration units connected to ductwork (Abatement Technologies family; NFS; Everetts; Groen).
US 5,230,723 / 5,433,763 / 5,588,985 all claim a portable filtration unit with detachable modules, an inlet, a debris screen, electrostatic filter, bag filter, and HEPA filter, and "means … comprising a motor coupled to a blower … for drawing a substantial volume of the fluid through the inlet and prefilter and filter." The 5,433,763 specification states the unit is wheel-mounted, modular, transportable to the work site, "can be quickly set up by a single person," is "suitable for use in high rise commercial buildings," "operates on standard household electric current," and that blowers in some embodiments "generate a total airflow of at least 4000 CFM." The inlet is defined at a 45° angle … "for facilitating attachment of the unit to ductwork." That is a duct-connected portable filter unit in the same field, with the same portability and volumetric-capacity objectives the '613 patent asserts as its own.
(US 5,417,729 NFS "portable modular air cleaning system," US 5,702,493 Everetts, and US 5,853,441 Groen "portable modular vacuum system" are further, unverified instances of the same genre.)

Cluster B — Negative-pressure enclosures/partitions + flexible ducting + treatment-and-return of air (Enviro-Air Control; Curtis; Daudelin; Lateste).
US 5,004,483 (and its continuation US 5,097,272) discloses: "defining a working space substantially sealed from space exterior," a temporary wall or barrier (expressly including plastic sheeting enclosures), "powering a portable air moving unit for exhausting air … to maintain a negative pressure within the working space," filtering the exhausted air, and returning the conditioned air to the working space (with a diverter regulating the split between exhausted and returned air). Contamination-escape prevention, portable air mover, filtration, and recirculation into an adjacent/occupied space are all there.
(US 4,905,578 Curtis "Apparatus for ventilating controlled areas," US 2,348,455 Daudelin "Portable collapsible fume extractor," and FR 2,675,717 Lateste are unverified but title-consistent members of this cluster — collapsible/portable partitions or hoods with suction for removing fumes from an operator's workspace.)

Cluster C — Flexible bag plenum inflated by fan pressure, with belt-driven fan and motor (Riutta).
US 5,312,465 (Island Clean Air Inc.) is the single most structurally relevant reference in the table:

• fan body with air intake and air outlet, a fan within the body "for drawing air into the intake and forcing it out of the outlet," and at least one air filter between the intake and the outlet;
• a plenum chamber connected to the fan body about the air outlet, where "the plenum chamber is a flexible bag of a sheet-like material which is inflated by air forced out of the outlet," and "is supported by air pressure therewithin when the apparatus is operational" (claim 20), "apart from the diffuser, … of a tightly woven textile" (claim 19), with a fan and a downstream secondary filter — i.e., blow-through: fan first, filter after the fan, then the receiving chamber;
• casters at each corner for portability;
• and, critically for the drive limitation: "The fan is powered by an electric motor 44 mechanically coupled to the impeller by means of sheaves 48 and 50 … and by a V-belt 52 …, with the explicit statement that 'Alternative types of fans and alternative means for coupling the fan to a motor could be employed in other embodiments of the invention.'"
• Field: recirculating dust-laden-air filtration for autobody/industrial shops — i.e., treating particulate- and VOC-laden air inside an occupied building and discharging it back into the room.

Cluster D — Multi-stage, series-arranged filter cabinets/chambers with carbon media, fed by ducts, with a blower creating negative pressure (Simon Roofing; Adsorbent Products; Control Resource Systems; Metal-Fab; Novobilski; Hayashikane).
US 5,873,919 / 5,591,244 / 6,022,389: "a plurality of filter chambers in fluid communication with one another," "each … a substantially airtight housing," "connected in an end to end relationship"; individual chambers containing treated filter paper, mesh filter, HEPA, and granular carbon; first and second ducts connecting fume sources to the filter inlet; and a blower creating negative pressure to move the fumes through filter(s) before discharge. This is the claim-18 architecture (a cabinet with plural series filter panels) plus the ducted topology.
(US 4,512,245 Adsorbent Products "portable point source adsorber," US 4,936,988 Control Resource Systems "air purification apparatus," US 5,281,246 Metal-Fab "air cleaner assembly," US 5,139,546 Novobilski (nail-vapor/dust), and US 4,446,861 Hayashikane (dental-room purification) are unverified but title-consistent members of this cluster.)

Cluster E — Emergency/elevated discharge, direct venting to atmosphere (Kenney US 667,149; Herriott US 2,747,201 — both unverified; and the general "venting to atmosphere" teaching in Simon Roofing's discharge-to-atmosphere claims). Kenney ("Fire apparatus," 1901) and Herriott ("Toilet deodorizer," 1956) are of marginal value; the emergency-discharge feature of the '613 specification (FIG. 7) is largely an apparatus-location argument, not a claim limitation, and appears in no claim. I therefore do not rely on it.

3. Independent claim 1 — the strongest § 103 challenge

Claim 1 requires only: (a) a first flexible duct; (b) a motor-driven blower unit with housing, inlet port, discharge port, and an interposed flow duct, plus a propulsion fan evacuating gas through the first duct and the flow duct; (c) a second flexible duct on the discharge port; (d) at least one filter unit at the far end of the second duct. It contains no partition, no isolation requirement, no hazardous-location requirement, and no plenum/multiple-filter requirement.

Combination A1 (primary): Enviro-Air US 5,004,483 + Abatement US 5,433,763

Motivation (KSR-compliant). All three references are in the same field of endeavor (portable air moving + filtration for confined/occupied interior spaces) and address the same problem the '613 patent recites: removing contaminant-laden air from an interior space at high volumetric flow with portable, household-current equipment. Enviro-Air '483 supplies the system insight (sealed space → portable air mover → filtration → return); Abatement supplies the apparatus insight (lightweight wheeled, modular, duct-connectable, multi-stage, standard-110 V, high-CFM filtration unit). A PHOSITA seeking to move a high-CFM filtration function from "on top of the air mover" to "remote but duct-connected" — motivated by the very portability, doorway-clearance, and high-rise constraints Abatement's own specification recites ("suitable for use in high rise commercial buildings"; modules sized to pass through doorways) — would predictably insert flexible duct runs between the blower and the filter. Assembling known air-handling elements in series with flexible duct is a predictable rearrangement of known components performing their known functions. There is no unexpected result in the mere insertion of duct between blower and filter; duct length/capacity trade-offs are ordinary engineering.

Strength: Strong as an obviousness rejection. Because claim 1 omits every hazard-related limitation, the rejection does not depend on any hazardous-location teaching at all.

Anticipation caveat (would be stronger if available). If Enviro-Air '483 (or '272) discloses first and second flexible duct sections in the claimed topology (blower between the two ducts, filter downstream of the blower — a blow-through arrangement), then claim 1 is potentially anticipated under § 102(b). Note, however, that '483 appears to be a draw-through system (blower/filtration unit exhausting the space, then conditioning and returning air), which does not match the claim's blower-between-two-ducts topology. I flag this as a factual gap I could not close from the retrieved text; a full-text check of '483/'272 columns is required before asserting anticipation.

Combination A2 (alternative): Riutta US 5,312,465 + Simon Roofing US 5,873,919 (or Abatement '763)

Riutta alone discloses the claim's blow-through sequence (air → intake → fan → secondary filter downstream of the fan → receiving chamber) and the receiving chamber downstream of the fan, but its chamber is a diffuser bag, not a filter unit, and it lacks flexible duct sections other than the plenum. Simon Roofing supplies ducting to a remote multi-chamber filter and a blower creating negative pressure through filter(s); Abatement supplies a wheeled multi-stage filter unit connected via a ducting port. Motivation: Riutta's own express teaching that "alternative means for coupling the fan to a motor could be employed" and that the bag plenum may be made of "alternative flexible, lightweight, sheet-like materials," combined with the art's well-known preference for remote filter placement to keep the air mover near the source while siting the filter where discharge is permissible, renders the substitution predictable. Strength: strong, though slightly weaker than A1 because it requires relocating Riutta's diffuser bag into a ducted, filter-outlet position.

4. Independent claim 20 — the harder, multi-reference challenge

Claim 20 is the real validity battleground. It requires, in combination: flexible partition with a port; first flexible duct; blower housing of non-sparking material with inlet/discharge ports and flow duct; fan driven by an electric motor via mechanical drive means, with both motor and drive isolated from contact with the evacuated gases; conductor connection means including an explosion-proof junction box and a power cord connectable at that junction box; second flexible duct; a portable plenum with a port; and a plurality of filter units mounted in the plenum discharging treated air. Six-plus distinct structural requirements, drawn across four technology clusters.

Combination B (recommended rejection): Enviro-Air '483 (or Curtis '578 / Daudelin '455) + Riutta '465 + Abatement '763 (or NFS '729) + Simon Roofing '919, with hazardous-location practice as the design impulse

Motivation, stated element-by-element.

1. Partition + negative pressure + filtration + return to the occupied space — Enviro-Air '483 states this as its invention and its advantage (preventing contaminant leakage from the work area into the rest of the building). The '613 patent claims the same advantage in nearly the same words ("without discharging unwanted gasses or vapors into other parts of a building"). Same problem, same field → strong motivation to use the partition/negative-pressure scheme.
2. Isolating motor and drive from the gas stream — the problem is expressly recognized in the art: direct-drive blowers "send fumes through the motor" and are neither hazardous-rated nor clog-resistant (the '613 specification says so; Riutta solves the clogging side by filtering before the fan and using a belt drive, which structurally allows the motor to be placed out of the airstream). Once the clogging/contamination problem and the ignition-source problem are both on the table, relocating a belt-driven motor and its belt guard entirely outside the gas-conveying duct is the paradigm solution in the fan art — the fan wheel in the duct, the motor and sheaves on an outboard pedestal, belt through a sealed gland. That is a predictable mechanical rearrangement with a known benefit and no change in the principle of operation.
3. Non-sparking housing + explosion-proof junction box + flame/abrasion-resistant cord — these are code- and insurer-driven requirements for equipment placed in a classified area. "[I]n many fields it is common sense to try" recognized solutions to well-known problems; where a regulation or standard (NEC Art. 500; OSHA 1910.307 practice; NFPA exhaust-system standards) dictates explosion-proof enclosures for equipment in a flammable-vapor atmosphere, the selection of an off-the-shelf sealed receptacle, non-sparking housing material, and rated cord is not inventive subject matter — and the patent admits each such item was commercially available.
4. Plenum + plural internal filter units discharging to the room — Riutta discloses the air-supported, portable, room-discharging receiving plenum and expressly contemplates alternative materials and drive couplings; Abatement discloses plural, removable, standardized filter modules in a transportable cabinet. A PHOSITA wanting a large-volume, low-restriction gas-treating station rather than a single narrow filter body would add filter modules to the receiving plenum's walls — a predictable capacity-scaling step with the known benefit of increased filter face area and reduced pressure drop.

Reasonable expectation of success. All elements are standard air-handling hardware that was demonstrably interoperable in 2001: ducted connection of blowers to filters (Simon Roofing; Abatement's 45° duct port), air-supported flexible plenums (Riutta), explosion-proof electrical fittings (commercial, per the specification), and belt-driven axial fans (commercially available, per the specification). Nothing in the combination requires a new principle of operation.

Strength: moderate-to-strong. It is a four-reference combination and therefore more vulnerable to a "no motivation to combine" or "impermissible hindsight" attack, but the motivation runs in the same direction as the problem statement and is supported by Riutta's express interchangeability teaching and by the specification's own admissions.

5. Dependent claims — element-by-element mapping

6. Where the rejection would fail — nonobviousness arguments the owner would make

1. The examiner already had all of this art and allowed the claims. The "Patent Citations" table shows 21–23 references considered, including the entire Abatement family, Riutta, Enviro-Air, and Simon Roofing. That does not create a presumption of validity beyond § 282, but it means a challenger must show a motivation the examiner did not credit — the burden is on the challenger to articulate it. (I have not reviewed the prosecution history, so I cannot say whether the claims were amended to overcome any particular reference; that record should be pulled.)
2. No single reference discloses the claim-20 isolation limitation in the claimed topology. In Riutta the motor and belt drive are mounted inside the fan body (on struts 60/62), not segregated outboard of a gas-conveying duct; Riutta's motor therefore is not "isolated from contact with said gasses" in the strict sense the claim recites. The patent owner will argue this distinction is exactly the point of the invention (the specification twice emphasizes that gases flow only through the interior of duct 60 and are exposed to no part of the blower unit). A challenger must therefore prove that outboard-motor belt-driven axial fans were a known, standard option — best proved not by the cited art but by Dayton/Greenheck/Chicago Blower catalog literature and NEC Art. 500 hazardous-location fan practice, which the '613 specification itself half-concedes ("The fan 61, the associated duct 60 and the motor 68 may be of a type commercially available … from Dayton Electric Manufacturing Company as one of their TUBEAXIAL brand axial flow fan units"). That concession is the single most useful admission in the document and should be developed with vendor literature.
3. Teaching away / industry failure. The specification asserts that (i) available >800 CFM blowers "are currently direct driven motors," (ii) HEPA systems cap out around 500 CFM, and (iii) >1000 CFM systems "use a 220 volt adapter commonly used for washers and dryers," unavailable in apartments, hotels, silos, and shops. If the art's own state was "portability and >1000 CFM and hazardous rating are mutually exclusive," that is a teaching-away-flavored argument. KSR cuts against it (industry failure may supply the motivation), but a court could credit it.
4. Secondary considerations with a plausible nexus. The previously generated section identified a documented long-felt need (the SBA/SBDC case study on the Teagle/Enviroblower business, sbaonline.sba.gov PDF) and the patent's own recitation of unmet need. Commercial success and long-felt need attach most cleanly to the claim-20 package (hazardous-rated, indirect-drive, >1000 CFM, standard-plug, portable), not to generic claim 1. Expect the owner to argue nexus on that basis and the challenger to argue that the success is attributable to the claimed combination only if the nexus is proven — but note that the specification's own admissions largely define the problem, which weakens the "long-felt need" story by showing the solution space was well mapped.
5. Claim construction risk cuts both ways. "Mechanical drive means" in claim 20 and "conductor connections means" are functional, means-plus-function-style recitations that, under 35 U.S.C. § 112 ¶ 6 (pre-AIA), are limited to the corresponding disclosed structures (enclosed belt drive 70 in case 66; explosion-proof junction box 56 with plug 58 and cords 48/50) and equivalents. Narrowing the claim to a belt drive enclosed in a housing external to the flow duct makes the Riutta-based obviousness argument harder (Riutta's belt is inside the fan body), while broadening it invites § 112 invalidity. This is the classic squeeze in mechanical validity practice.

7. Bottom line

Overall confidence. High that claim 1 and the plenum/filter-train dependents are obvious over the cited art. Moderate that claim 20 is obvious on the cited record alone. Moderate that claim 20 becomes clearly obvious with supplementary standard/catalog evidence. Low that claims 9 and 23 (dual power cords) are obvious on this record.

8. Explicit uncertainties

• Unverified reference contents. US 2,348,455, US 4,163,650, US 4,446,861, US 4,512,245, US 4,905,578, US 4,936,988, US 5,139,546, US 5,281,246, US 5,417,729, US 5,702,493, US 5,853,441, and FR 2,675,717 were confirmed only as citation-table entries. Any mapping above that relies on them (chiefly claims 3, 4, and the "alternate partition" cluster) should be re-checked against their full texts before being asserted. Searches for US 5,417,729 and US 5,853,441 were cut off before returning content.
• Enviro-Air '483 duct topology unconfirmed. Whether '483/'272 disclose flexible first/second ducts in the claimed blow-through, blower-between-two-ducts topology is unresolved; this governs whether claim 1 is anticipated (a stronger, cleaner holding) or merely obvious.
• Prosecution history not reviewed. Whether any claim was amended, and on what basis, is unknown to me. Claims allowed over 21–23 references usually carry some amendment or examiner reasoning worth reading before a validity opinion is finalized.
• No vendor/standard art searched. The decisive supplemental art for claim 20 is hazardous-location belt-driven axial fan practice (NEC Art. 500; NFPA 91; UL 705; Dayton "TUBEAXIAL" and equivalent catalogs). I did not search it, and my claim-20 conclusion would strengthen if it exists in printed-publication form before 2001-02-21.
• "Cited By" tables are not prior art here. With the single flagged exception of Goyetche (priority 2000-08-16, unverified), the 66- and 99-row "Cited By" tables post-date the '613 filing and cannot support a § 102/§ 103 rejection against it (they are, however, evidence of the crowdedness and predictability of the field, and of the persistence of the problem).