Gate valves are generally used in the process industry for on-off service. The design is not suitable for throttling duty because the sealing surfaces can easily suffer from wire drawing (erosion) when low flows are being maintained against high differential pressures and the design give very poor flow control characteristics.

The gate valve can be manufactured in a wide range of sizes from 50mm to above 1200mm dia. 

The valve can be based on a solid wedge, a wedge which can adjust to suit the seal faces, or a parallel faced based on two discs which slide between parallel sealing faces with a mechanism form forcing the discs out on the last part of the spindle travel.  The valve can be based on a simple rising spindle design or a fixed spindle which screws into the gate..