Bibliographic record
Abstract
The paper extends existing methods of calculating the hold time for a fire extinguishing gas in an enclosure to cover mechanical HVAC systems and wide descending interfaces, and compares the wide descending interface model’s predictions with some experimental data. A simple approximation to the measured wide descending interface gives conservative hold time predictions, while the sharp descending interface model used in current standards gives optimistic predictions. In the fire protection industry, ‘Fan Integrity Testing’ denotes the tests and leakage modelling carried out to determine the airtightness (or leakage) of an enclosure, and the use of the information to predict the rate of decay of the concentration of a fire suppression gas (‘agent’) at any particular height in the enclosure. Prior to the Montreal Protocol, which brought about the end of Halon 1301 production, serious concerns were being expressed over the number of instances where the required lo-minute hold time was not being achieved. ‘Hold time’ or ‘retention time’ denotes the time taken for the agent concentration at a specified height (usually the highest hazard in the protected enclosure) to fall below a specified concentration (usually 80% of the minimum design concentration). A lo-minute hold time was, and still is, considered important to allow ignition sources to cool and to allow sufficient time for manual intervention to ensure that the danger has passed. Practical enclosures are not perfectly airtight. Pressure differences due to density differences between inside and outside, wind or HVAC systems cause air to flow in and out through leaks in the enclosure. The quantity of agent inside gradually falls as it leaves with the outgoing air. The discharge of the agent into the enclosure generally creates good mixing initially; the uniformity of the later agent distribution in the enclosure depends on the internal airflows during the hold time. Fan integrity testing standards set out methods of measuring enclosure leakage and calculating hold time, using assumptions about the locations of the enclosure
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.018 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.004 | 0.004 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.004 |
| Open science | 0.005 | 0.002 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.044 | 0.028 |
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.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".