What is a gate valve or a sluice valve ?
A gate valve, is a valve that opens up by lifting a barrier which is referred to as the "gate". This gate is lifted out of the way so the fluid can flow. Some advantages of gate valves is that they need little space along the pipeline. They also barely interrupt the flow of fluid when the gate is fully opened. The gate faces can be parallel but are more often wedge-shaped which is beneficial because it is able to apply pressure on the sealing surface.
When are Gate valves used ?
Gate valves are mostly used with larger pipe diameters (from 2" to the largest pipelines). This is because the engineering of a gate valve is relatively simpler than other valves especially in larger sizes. These valves are also used out of convenience and affordability in heating circuits or sewer pipes.
Gate valves are used to stop the flow of liquids; they are not really used for flow regulation as they lack precision. When fully opened, the typical gate valve does not obstruction the flow, giving it a benefit of very low flow resistance.
Issues faced with Gate Valves are that at high pressures, friction becomes an issue. The gate is pushed against the valves guiding rail by the pressure, this makes it harder to operate the valve.