clack valve vs clapper valve

clack valve and clapper valve both are nouns.

Word	Noun	Adjective	Verb	Adverb
clack valve	Yes	No	No	No
clapper valve	Yes	No	No	No

As nouns, clack valve and clapper valve are synonyms defined as:

clack valve and clapper valve: a simple valve with a hinge on one side; allows fluid to flow in only one direction

Other synonyms of clack valve include clack.

clack valve (noun)	clapper valve (noun)
a simple valve with a hinge on one side; allows fluid to flow in only one direction	a simple valve with a hinge on one side; allows fluid to flow in only one direction