Marine Anti Siphon Valve

anti siphon
A device that prevents waste water from being drawn back into supply lines and possibly contaminating the water supply.
Preventive device for the backflow of liquid into a system. Used on sprinkler systems to prevent water from trickling back into the supply that is feeding it.

marine
Of, found in, or produced by the sea
of or relating to the sea; "marine explorations"
(of artists or painting) Depicting scenes at sea
a soldier who serves both on shipboard and on land
a member of the United States Marine Corps
Of or relating to shipping or naval matters

valve
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 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
control consisting of a mechanical device for controlling the flow of a fluid
device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it
A device for controlling the passage of fluid through a pipe or duct, esp. an automatic device allowing movement in one direction only