Rotopax and diesels

Red means that the Rotopax doesn't carry enough gasoline, to matter in the slightest.

Yellow means that the Rotopax doesn't carry even close to enough diesel fuel, to make the slightest difference.

Blue means that the Rotopax is perfect for starting campfires with Kerosene

Green means that the Rotopax is mounted on a Powerwagon that has a failling cam, lifters, rings, and is drinking oil (again).

Black means ''Who the #$%& did a number 2 in my Rotopax''.

White means that the Rotopax is empty, it's water contents have been wasted by your wife.

Blue Rotopax (is Rotopax plural for Rotopax's?) is the best Rotopax. California agrees.
 
Just got a Diesel engine and have never had Rotopax before. Is there a technical reason for the different colors?
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Container colors simply indicate the type of liquid stored, so the user does not put gas in a diesel rig, or diesel in a gas rig. These colors have been used for containers for a long time:

 
At Edison we marked the same way with Gas as Red and Diesel as Orange, Water as blue, Hyd. Oil is Green, and so on. The caps of the tanks were marked in the same way , and still people messed them up. I hate to tell you how many times we had to drain 50 gals of mixed fuel and filters to get them running again.
 
Diesel is commonly marked yellow in some way, cap or colored band or the whole canister. In private use it does not really matter and there is no technical reason, the material of the canister for gasoline or diesel is the same.