| Contents | Examples | Colour | |
| Water | Brine, condensate, water (hot or cold) | Green | |
| Steam | Stream (high and low pressure) | White | |
| Air | High or low pressure air, vacuum | Light blue | |
| Gases | Ammonia, Chlorine, Natural gas, Nitrogen, Oxygen | Orange | |
| Acids and alkalis | Ammonia solution, Caustic, Hydrochloric, Nitric, Phosphoric, Sulphuric acids | Blue violet | |
| Oils and combustible | Benzine, Diesel, Formaldehyde, Glycol, Lubricating oils, Used Solvents | Brown | |
| Other liquids | Beer, Milk, Refrigerated liquids, Radioactive | Black | |
| Fire | Foam, Fire main, Sprinklers | Red | |
