Pipe marking solutions to meet British Standard 1710 (BS 1710) Pipe Contents Name ReferenceColourBS 4800 Colour Oils (mineral, vegetable or animal)Brown06 C 39 Gases (in either gas or liquid phase – except air)Yellow Ochre08 C 35 Acids / AlkalisViolet22 C 37 AirLight Blue20 E 51 4 more rows