Check Valve 1

check valve
A valve that closes to prevent backward flow of liquid
A check valve, clack valve, non-return valve or one-way valve is a mechanical device, a valve, which normally allows fluid (liquid or gas) to flow through it in only one direction.
Limits the flow of gas to one direction only. Use a check valve between the bubbler and generator to prevent unwanted pressure build up in the generator, and a safety against a low level bubbler. A check valve, such as used on torches, is recommended.
A mechanical device in a pipe that permits the flow of water or air in one direction only.

1
one: the smallest whole number or a numeral representing this number; "he has the one but will need a two and three to go with it"; "they had lunch at one"
one: used of a single unit or thing; not two or more; "`ane' is Scottish"
"?1" (read "Infinity Ichi"; translated as "Infinity 1") is Do As Infinity's twenty-first single, released on June 17, 2009. The band had disbanded in September 2005, but reformed three years later in September 2008.