Identifiers for search
| Name | Propane |
| Formula | C₃H₈ |
| IUPAC name | propane |
| CAS number | 74-98-6 |
| EC number | 200-827-9 |
| UN number | 1978 — Propane |
| Transport class (ADR/RID) | 2.1 (Flammable Gases) |
| PubChem CID | 6334 |
| Synonyms | Bottled gas, Dimethyl methane, n-Propane, Propyl hydride |
Physical & chemical properties
| Molar mass | 44.1 g/mol |
| Boiling point (1 atm) | -42.1 °C |
| Melting point | -187.7 °C |
| Critical temperature | 96.8 °C |
| Critical pressure | 42.6 bar |
| Vapour pressure | 8.367 bar at 20 °C |
| Gas density | 2.0098 kg/m³ (0 °C, 1013 mbar) |
| Relative density (air = 1) | 1.55 |
| Solubility in water | 42,4 ml/l at 20 °C |
| Appearance | gas liquefied under pressure, colourless, odourless |
| Odour | odourless |
| 1 ppm at 20 °C | 1.83 mg/m³ |
Behaviour with temperature and pressure
Boiling point -42.1 °C at 1 atm: a liquefied gas under its own vapour pressure in cylinders. Critical point 96.8 °C / 42.6 bar: below this temperature it can be stored as a liquid; cylinder pressure then equals the vapour pressure. Vapour pressure ≈ 8.367 bar at 20 °C — this is the pressure inside a cylinder or a switchgear compartment at that temperature, and it rises steeply with temperature (Clausius–Clapeyron). Relative density 1.55 (air = 1): heavier than air — accumulates in pits, cable basements and at floor level; place sensors low. Conversion at 20 °C, 1013 mbar: 1 ppm = 1.83 mg/m³; NDIR reads partial pressure, so readings scale with absolute pressure (value = reading × P/1013) and must be pressure-compensated.
// Extremely flammable gas. Forms hazardous explosive mixtures with air., Only slightly soluble in water., Gas is heavier than air.
Hazards & safety
NFPA 704
health · flammability · instability · special
GHS / CLP pictograms
| Hazard class | flammable (simple asphyxiant) |
| GHS signal word | Danger |
| CLP classification | Flammable gases, Category 1; H220 Gases under pressure, liquefied gas; H280 |
| Hazard statements | H220: Extremely flammable gas. H280: Contains gas under pressure; may explode if heated. |
| Lower / upper explosion limit | 1.7 vol% / 10.8 vol% |
| Auto-ignition temperature | 470 °C · T1 · group IIA |
| Seveso III named substance | yes |
Exposure limits
| EU indicative OELV (8 h TWA) | no EU IOELV |
| EU IOELV short-term (15 min) | — |
| Germany AGW (TRGS 900) | 1000 ppm · 1800 mg/m³ |
| Netherlands | wettelijke grenswaarde per Arboregeling bijlage XIII — SER grenswaarden database |
| NIOSH REL (USA) | TWA 1000 ppm (1800 mg/m3) |
| OSHA PEL (USA) | TWA 1000 ppm (1800 mg/m3) |
| IDLH | 2100 ppm [10%LEL] |
// Limits change: always confirm the current national value before setting an alarm. Values above were read from the EU directives / GESTIS / NIOSH pages listed in Sources.
Effect on people
Simple asphyxiant and mild CNS depressant at high %; NIOSH REL 1000 ppm. Main hazard is fire/explosion (LEL 1.7 vol%); 1.5× heavier than air — accumulates at floor level.
GESTIS main toxic effects: Acute:
Frostbite following skin contact with the gas which has been let down;
central-nervous disturbances;
in extreme situations suffocation due to oxygen deficiency
Chronic:
Dessication of the mucous membranes, cough, gastrointestinal disturbances and functional changes to the heart through high concentrations
Recommended monitoring
- NDIR (3.4 µm) for %LEL detection of LPG in boiler rooms, forklifts halls, LPG stores; catalytic beads for legacy loops. Heavier than air — sensors 30 cm above floor.
- Alarms 10 %LEL / 20 %LEL (EN 60079-29-1 systems).
Climate & atmosphere
| GWP₁₀₀ — IPCC AR6 | — |
| GWP₁₀₀ — IPCC AR4 | — |
| GWP used in Reg. (EU) 2024/573 | not listed |
| Atmospheric lifetime | — |
| Ozone depletion potential | 0 |
| Main IR absorption band (NDIR) | 3.4 µm (C–H stretch, 2960 cm⁻¹); 6.8–7.2 µm (CH₂/CH₃ deformation) |
Regulation windows
- ATEX / EN 60079-29-1 — %LEL detection; LPG installations
- Workplace: NIOSH REL 1000 ppm; DE AGW 1000 ppm
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Tremon Solutions (2026). Propane (C₃H₈) — properties, exposure limits, NDIR monitoring. Tremon gas reference. https://www.tremon.nl/gases/c3h8 (accessed 2026-09-17).
BibTeX · embed card · QR
@misc{tremon_c3h8_2026,
author = {Tremon Solutions},
title = {Propane (C3H8) — properties, exposure limits, NDIR monitoring},
howpublished = {Tremon gas reference, \url{https://www.tremon.nl/gases/c3h8}},
year = {2026},
note = {accessed 2026-09-17}
}<a href="https://www.tremon.nl/gases/c3h8"><img src="https://www.tremon.nl/assets/og/c3h8.png" alt="Propane — Tremon gas reference" width="600"></a>
Text and tables on this page: CC BY 4.0 — copy them into your report, SOP or slide with the link above. Data were read from the primary sources listed below; check the current national limit before setting an alarm.
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https://www.tremon.nl/gases/c3h8 · Tremon Solutions, Eindhoven · [email protected] · printed from the Tremon gas reference, data as of 2026-09-17 · CC BY 4.0Sources
- https://gestis-database.dguv.de/data?name=010020
- https://www.cdc.gov/niosh/npg/npgd0524.html
- https://pubchem.ncbi.nlm.nih.gov/compound/6334
- IPCC AR6 WG1 Ch.7 Supplementary Material, Table 7.SM.7 (https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter07_SM.pdf)
- HITRAN/NIST IR band positions (approximate centre of the strongest band used for NDIR; https://hitran.org, https://webbook.nist.gov)
// Data compiled 2026-09-17 from the listed primary sources; null values were left blank rather than estimated.