1. non-return - Noun
2. non-return - Adjective
non-return (uncountable)
Alternative form of nonreturn
non-return (not comparable)
Alternative form of nonreturn
However, these are not mechanical but instead rely on the elastomeric properties of the main valve and non-return valve which are low-cost, reliable and easy to replace. Source: Internet
In some pipes the player must cover the tip of the blowpipe with their tongue while inhaling, but most blowpipes have a non-return valve that eliminates this need. Source: Internet
Return valves and non-return valves allow fluid to move in 2 or 1 directions respectively. Source: Internet