SGI’s BS 341 British Standard Cylinder Valve Outlets and Connections:

British standard valve outlet connections follow a few simple rules:
- If the gas mixture has a flammable and toxic component, then the BS 15 connectors are
used.
- If the gas mixture has a flammable component but no toxic component, then the BS 4
connectors are used.
- If the gas mixture has a toxic component but no flammable component, then BS 14
connectors are used.
- If the gas mixture has neither a toxic nor a flammable component, BS 3 connectors are used.
For a detailed understanding of the British standard cylinder valve outlets and connections, please refer to the table below:
| Gas | BS |
|---|---|
| Acetylene | 2 |
| Air | 3 |
| Ammonia, Anhydrous | 10 |
| Argon | 3 |
| Arsine | 4 |
| 1,3-Butadiene | 4 |
| Butane | 4 |
| Butenes | 4 |
| Carbon Dioxide | 8 |
| Carbon Monoxide | 4 |
| Chlorine | 6 |
| Deuterium | 4 |
| Dimethylamine | 11 |
| Ethane | 4 |
| Ethyl Chloride | 7 |
| Ethylene | 4 |
| Ethylene Oxide | 7 |
| Halocarbon-14 (Tetrafluoromethane) | 6 |
| Halocarbon-22 (Chlorodifluoromethane) | 6 |
| Helium | 3 |
| Hydrogen | 4 |
| Hydrogen Chloride | 6 |
| Hydrogen Sulfide | 15 |
| Iso-Butane | 4 |
| Iso-Butylene | 4 |
| Krypton | 3 |
| Methane | 4 |
| Methyl Chloride | 7 |
| Monoethylamine | 11 |
| Monomethylamine | 11 |
| Natural Gas | 4 |
| Neon | 3 |
| Nitric Oxide | 14 |
| Nitrogen | 3 |
| Nitrogen Dioxide | 14 |
| Nitrous Oxide | 13 |
| Oxygen | 3 |
| Phosgene | 6 |
| Phosphine | 4 |
| Propane | 4 |
| Propylene | 4 |
| Sulfur Dioxide | 12 |
| Sulfur Hexafluoride | 6 |
| Trimethylamine | 11 |
| Vinyl Chloride | 7 |
| Xenon | 3 |