The sluice valve , also known as a gate valve, is a valve that opens by lifting a round or rectangular gate/wedge out of the path of the fluid. The distinct feature of a sluice valve is the sealing surfaces between the gate and seats are planar, so sluice valves are often used when a straight-line flow of fluid and minimum restriction is desired. Gate valves are primarily used to permit or prevent the flow of liquids.
Gate valves are characterised as having either a rising or a non-rising stem. Rising stems provide a visual indication of valve position because the stem is attached to the gate such that the gate and stem rise and lower together as the valve is operated. Non rising stem valves may have a pointer threaded onto the upper end of the stem to indicate valve position, since the gate travels up or down the stem on the threads without raising or lowering the stem. Non rising stems are used underground or where vertical space is limited.
Bonnets provide leak proof closure for the valve body. Gate valves may have a screw-in, union, or bolted bonnet.
Gate valves may have flanged ends which are drilled according to pipeline compatible flange dimensional standards. Gate valves are typically constructed from cast iron, ductile iron, cast carbon steel, gun metal, stainless steel, alloy steels, and forged steels.