Division 1.3 Symbols and abbreviations for the chemical components (used also as a subscript)
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| Section 2 | Section 3 | Quantity |
|---|---|---|
| Ar | Ar | Argon |
| C1 | C1 | Carbon 1 equivalent hydrocarbon |
| CH4 | CH4 | Methane |
| C2H6 | C2H6 | Ethane |
| C3H8 | C3H8 | Propane |
| CO | CO | Carbon monoxide |
| CO2 | CO2 | Carbon dioxide |
| H | Atomic hydrogen | |
| H2 | Molecular hydrogen | |
| HC | HC | Hydrocarbon |
| H2O | H2O | Water |
| He | Helium | |
| N | Atomic nitrogen | |
| N2 | Molecular nitrogen | |
| NOx | NOx | Oxides of nitrogen |
| NO | NO | Nitric oxide |
| NO2 | NO2 | Nitrogen dioxide |
| O | Atomic oxygen | |
| PM | PM | Particulate matter |
| S | S | Sulphur |