Gate Valve

 

Gate valve is a sliding type of valve in which closing member is a metal gate which slides down to stop the flow. In fully open conditions, the flow area is equal to the area of the pipe and hence, pressure drop across the valve is minimum.

It is highly recommended to use gate valve as on-off valve and not to throttle the flow because, in partly open condition, the closure member, i.e. the gate can get eroded. The disk of a gate valve is removed completely when the valve is fully open; the disk is fully pulled up into the valve bonnet. This leaves an opening for flow through the valve of the same inside diameter as the pipe system in which the valve is installed.

Also, in partially open conditions, the valve vibrates leading to fast wear and tear. The opening and closing operations are slow. Friction between the sliding parts limits the use of gate valves for applications where frequent on-off is required. Due to presence of frictional forces and the force exerted by the fluid flow, large actuators are required to operate these valves.

These valves find their use in petrochemical industry due to the fact that they can work with metal-metal sealing