Cylinder vs. tank -

[Lubomir I. Ivanov]

if one goes in google and searches for the actual English dictionary
meaning of the word "tank" (not the armored vehicle), he/she might
find that the majority of dictionaries have the adjective "large" in
the descriptions for the word.

examples:
http://www.dictionary.com/browse/tank
"a large receptacle, container, or structure for holding a liquid or gas"
https://www.collinsdictionary.com/dictionary/english/tank
"A tank is a large container for holding liquid or gas."
https://www.merriam-webster.com/dictionary/tank
"a usually large receptacle for holding, transporting, or storing
liquids (such as water or fuel)"

the containers on ones back when scuba diving are far from "large",
which implies that unless the word "tank" is used prefixed with
something like "small", one might assume that the word is misused or
just slang.
on the other hand, "cylinder" is quite vague, as it's a geometric
object if not prefixed with "gas"...and still seems like slang.

in my country we call them "bottles" and both "tanks" and "cylinders"
don't translate well as they have different and or vague(er) meanings.

lubomir
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