Colour Coding of Standard Gases

We've decided to start using a colour coding system for all of our decompression and bail-out tanks as part of our annual stage tank overhaul.

The intention of this isn't to use the colour coding underwater, but to make visual recognition of tanks much easier on the surface, especially then having tanks passed town from boats on while donning tanks at the shoreline.

The colour coding also provides a quick visual reference underwater (we only used colours at the end of the visual spectrum - i.e. black, white, greens and blues).

We normally use standard gases for all our courses;

Black on White - Oxygen for Decompression from 6m upward
White on Black - 50% Nitrox for Decompression from 21m upward
White on Blue - Trimix 18/45 from 67m upward
White on Green - Trimix 10/70 from 130m upward.

The only other standard gas we use tend to use for decompression is Trimix 35/25 which we tend to make specifically for dives rather than have as a pre-filled standard gas.