The flash point of elemental sulfur: Effect of heating rates, hydrogen sulfide, and hydrocarbons
Bibliographic record
Abstract
Facilities for the storage and handling of liquid sulfur are designed to avoid fires to prevent (a) deflagration, (b) breaching of hot-liquid and (c) the emission of highly toxic sulfur dioxide. To aid design and operation, current literature reports a wide range of flash points from 160 to 207 °C. This work aims to help clarify why this wide variance in measurements exists and which values are more applicable for safety and vessel integrity. The effects of heating rate, dissolved hydrogen sulfide, and hydrocarbon impurities on the apparent flash point were studied using a Pensky-Martens closed cup flash point apparatus following the standardized procedure outlined in American Society for Testing and Materials test method D93-20. The heating rate significantly affected the sulfur flash point, where slower rates yielded consistent flash points of 207 ± 3 °C. Flash points as low as 167 °C were observed when using faster rates, including the American Society for Testing and Materials recommended heating rates. Freely dissolved hydrogen sulfide lowered the flash point to 175 °C for concentrations greater than 100 ppmw, irrespective of the amount of dissolved polysulfanes. No effect on the flash point was observed for decane or hexadecane impurities up to 333 and 512 ppmw, respectively.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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.
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".