| Property | Units | Hydrogen | Methane | Propane | Methanol | Ethanol | Gasoline |
|---|---|---|---|---|---|---|---|
| Chemical Formula | H2 | CH4 | C3H8 | CH3OH | C2H5OH | CxHy (x = 4 - 12) | |
| Molecular Weight [a, b] | 2.02 | 16.04 | 44.1 | 32.04 | 46.07 | 100 - 105 | |
| Density, NTP [3, a, c] | kg/m³ | 0.0838 | 0.668 | 1.87 | 791 | 789 | 751 |
| lb/ft³ | 0.00523 | 0.0417 | 0.116 | 49.4 | 49.3 | 46.9 | |
| Viscosity, NTP [3, a, b] | g/cm-sec | 8.81 E-5 | 1.10 E-4 | 8.012 E-5 | 9.18 E-3 | 0.0119 | 0.0037 - 0.0044 |
| lb/ft-sec | 5.92 E-6 | 7.41 E-6 | 5.384 E-6 | 6.17 E-4 | 7.99 E-4 | 2.486 E-4 - 2.957 E-4 | |
| Normal Boiling Point [a, b] | °C | -253 | -162 | -42.1 | 64.5 | 78.5 | 27 - 225 |
| °F | -423 | -259 | -43.8 | 148 | 173.3 | 80 - 437 | |
| Vapor specific gravity, NTP [3, a, d] | air = 1 | 0.0696 | 0.555 | 1.55 | N/A | N/A | 3.66 |
| Flash Point [b, d] | °C | <-253 | -188 | -104 | 11 | 13 | -43 |
| °F | <-423 | -306 | -155 | 52 | 55 | -45 | |
| Flammability Range in Air [c, b, d] | vol% | 4.0 - 75.0 | 5.0 - 15.0 | 2.1 - 10.1 | 6.7 - 36.0 | 4.3 -19.0 | 1.4 - 7.6 |
| Auto ignition temperature [b, d] | °C | 585 | 540 | 490 | 385 | 423 | 230 - 480 |
| °F | 1085 | 1003 | 914 | 723 | 793 | 450 - 900 | |
| Maximum flame velocity in air [2, c] | m/s | 2.83 | 0.45 | 0.46 | N/A | N/A | N/A |
| ft/s | 9.28 | 1.48 | 1.52 |
Notes:
- Properties of the pure substance
- Properties of a range of commercial grades
- NTP = 20°C (68°F) and 1 atmosphere
- N/A - Not applicable
Source:
"Alternatives to Traditional Transportation Fuels: An Overview." DOE/EIA-0585/O. Energy Information Administration. U.S. Department of Energy. Washington, DC. June 1994
Perry's Chemical Engineers' Handbook (7th Edition), 1997, McGraw-Hill
"Hydrogen Fuel Cell Engines and Related Technologies. Module 1: Hydrogen Properties." U.S. DOE. 2001