gas-washing bottle vs gas washing bottle

gas-washing bottle and gas washing bottle both are nouns.

Word	Noun	Adjective	Verb	Adverb
gas-washing bottle	Yes	No	No	No
gas washing bottle	Yes	No	No	No

As nouns, gas-washing bottle and gas washing bottle are synonyms defined as:

gas-washing bottle and gas washing bottle: a bottle used for saturating a liquid with a gas.

gas-washing bottle (noun)	gas washing bottle (noun)
a bottle used for saturating a liquid with a gas.	a bottle used for saturating a liquid with a gas.