What's the plural form of liquefied petroleum gas? Here's the word you're looking for.
Answer
The noun liquefied petroleum gas can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be liquefied petroleum gas.
However, in more specific contexts, the plural form can also be liquefied petroleum gases e.g. in reference to various types of liquefied petroleum gases
or a collection of liquefied petroleum gases.