Wafer Non Return Valve

return
Come or go back to a place or person
tax return: document giving the tax collector information about the taxpayer's tax liability; "his gross income was enough that he had to file a tax return"
Go back to (a particular state or activity)
Turn one's attention back to (something)
go or come back to place, condition, or activity where one has been before; "return to your native land"; "the professor returned to his teaching position after serving as Dean"
a coming to or returning home; "on his return from Australia we gave him a welcoming party"

wafer
a small adhesive disk of paste; used to seal letters
a small thin crisp cake or cookie
thin disk of unleavened bread used in a religious service (especially in the celebration of the Eucharist)
Fasten or seal (a letter, document, etc.) with a wafer

valve
A membranous fold in a hollow organ or tubular structure, such as a blood vessel or the digestive tract, that maintains the flow of the contents in one direction by closing in response to any pressure from reverse flow
device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
A device for controlling the passage of fluid through a pipe or duct, esp. an automatic device allowing movement in one direction only
A cylindrical mechanism in a brass instrument that, when depressed or turned, admits air into different sections of tubing and so extends the range of available notes
a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it
control consisting of a mechanical device for controlling the flow of a fluid