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Record W2275855945 · doi:10.1002/prs.11806

Limiting oxygen concentrations of gases

2016· article· en· W2275855945 on OpenAlex

Why this work is in the frame

A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.

affAt least one author lists a Canadian institution in the pinned OpenAlex snapshot.

Bibliographic record

VenueProcess Safety Progress · 2016
Typearticle
Languageen
FieldEngineering
TopicCombustion and Detonation Processes
Canadian institutionsDalhousie University
Fundersnot available
KeywordsOverpressureCabin pressurizationIgnition systemFlammable liquidVolume (thermodynamics)LimitingNuclear engineeringHead (geology)MechanicsEnvironmental scienceMechanical engineeringForensic engineeringEngineeringWaste managementThermodynamicsGeologyAerospace engineeringPhysics

Abstract

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This article discusses technical and practical aspects of the limiting oxygen concentration (LOC) including a detailed appraisal of possible sources of measurement error. LOC values obtained in the “classical” 5‐cm diameter, vertical tube apparatus have been described as nonconservative owing to flame quenching. However, much of the difference between classical LOC values and those obtained in closed vessels using ASTM E2079 is due to the change in the definition of “ignition.” Formerly defined as propagation of a visible flame through a vertical tube at least 1.5 m tall, which in a closed tube would typically generate an overpressure in excess of 100%, ignition is now defined as an overpressure that exceeds 7%. The small pressure rise criterion tends to underestimate the LOC in smaller test vessels, especially for tests made at elevated pressures and temperatures. More use should be made of ASTM E2079's flexibility regarding the use of larger pressure rise criteria. Having lost sight of the flame, it is important not to lose sight of the objective, namely to select test criteria that correctly predict the flammable limits pertaining to large volumes of gas mixture. Additional “reference quality” LOC data are needed both to improve the definition of “ignition” with respect to test vessel volume and to investigate the accuracy of LOC estimation techniques. Any large‐scale reference quality test program should investigate the effect of low levels of forced turbulence on measured LOC values. The NFPA “Explosion Protection Systems” Technical Committee recently supported the development of two Tentative Interim Amendments (TIAs) to NFPA 69 “Standard on Explosion Prevention Systems.” The first TIA resolves issues with the table of LOC values for gases, which had been modified and over‐corrected in the 2008–2014 editions. The second TIA introduces a simple method for estimating the LOCs of single gases and gas mixtures based on the equation LOC = LFL × S, where LFL is the lower flammable limit and S the molar stoichiometric ratio of oxygen to fuel. An Appendix describes the two TIA recommendations while a second Appendix describes how the estimating methods have been incorporated into ASTM's “CHETAH” Program. © 2016 American Institute of Chemical Engineers Process Saf Prog 35: 107–114, 2016

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Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: none
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.796
Threshold uncertainty score0.318

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0000.000

Machine scores (provisional)

The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.

Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.

Opus teacher head0.013
GPT teacher head0.250
Teacher spread0.237 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it