A gate valve is a valve that opens by lifting a round or rectangular gate/wedge out of the path of the fluid. The main feature of a gate valve is the sealing surfaces between the gate and seats are planar. The gate faces can form a wedge shape or they can be parallel. Gate valve is sometimes used for regulating flow, but many are not suited for that purpose. Gate valve is characterized as having either a rising or a nonrising stem. Rising stems provide a visual indication of valve position. Nonrising stems are used where vertical space is limited or underground.
Gate valve is referred to stop valves or block valves. The flow control element of a gate valve enters the fluid path from the side and traverses it until the fluid path is completely closed off, stopping the flow. When the valve is open, the gate is entirely out of the fluid path. Thus flow is in straight line, with very little resistance from the valve. The form of control for which gate valves are suited is starting and stopping flow.