The unspoken language of colors

As you know there is no a written international standard defining color of ball valve handles and very often approval authorities do not specify it either.
Although some companies do prefer to have the handle of the same colour of their brand, it is international practice to define colour in consideration of the fluid passing in the ball valve:

Red - to define water use
Blue – for pneumatic applications
Yellow - for gas applications
Black – for industrial applications (oils & lubricant)
Green - for drinking water
white - for oxygen

The reason why color differentiation depends on the media is clear: you can’t see whats in the pipeline and a color handle gets your attention before you operate the valve: Can you imagine what it would happen if you operate a ball valve thinking there's water in it, while there's gas?