Parallel Slide Gate Valve

slide gate
A steel gate that upon opening or closing slides on its bearings in edge guide slots. A gate that can be opened or closed by sliding in supporting guides.
Generally 4, 5 or 6 feet in length. The gate is designed to slide along the edge of the mezzanine to allow access to the mezzanine. It can be opened either manually or electrical power.

parallel
(of something extending in a line) Be side by side with (something extending in a line), always keeping the same distance
Be similar or corresponding to (something)
be parallel to; "Their roles are paralleled by ours"
being everywhere equidistant and not intersecting; "parallel lines never converge"; "concentric circles are parallel"; "dancers in two parallel rows"
analogue: something having the property of being analogous to something else

valve
A device for controlling the passage of fluid through a pipe or duct, esp. an automatic device allowing movement in one direction only
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
control consisting of a mechanical device for controlling the flow of a fluid
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