Gate Valves
Gate valves incorporate a sliding gate to block fluid flow (slide gate valves). The design of the valve operating and sealing systems typically requires that they should be operated either fully open or fully closed.
They open by lifting a round or rectangular gate/wedge out of the path of the fluid. The distinct feature is the sealing surfaces between the gate and seats are planar. The gate faces can form a wedge shape or they can be parallel. Typically, they should never be used for regulating flow, unless they are specifically designed for that purpose.
They are characterized as having either a rising or a non-rising stem. Rising stems provide a visual indication of valve position. Non-rising stems are used where vertical space is limited or underground.