Gate valves are also known as sluice valves. They open by lifting a round or even rectangular gate or wedge out of the path of the fluid flow. The very distinct feature of the gate valve is the sealing surface that is between the gate and seats are planar. This makes it easier on a straight line flow of fluid with minimum restriction.
The gate faces can form a wedge shape or they can be parallel. These gate valves are primarily used to permit or even prevent the flow of any liquid, typical gate valve shouldn’t be used for when you need to regulate any flow, unless they are designed specifically for this.
Due to gate valves ability to cut through liquids, gate valves are often used in the petroleum industry. On opening the gate valve, the flow path is enlarged in a highly nonlinear manner with respect to percent of opening. This means that flow rate does not change evenly with stem travel. Also, a partially open gate disk tends to vibrate from the fluid flow. Most of the flow change occurs near shutoff with a relatively high fluid velocity causing disk and seat wear and eventual leakage if used to regulate flow. Typical gate valves are designed to be fully opened or closed
When fully open, the typical gate valve has no obstruction in the flow path, resulting in very low friction loss