A valve is simply a device that directs or regulates flow by opening, closing or partially obstructing passageways.
Gate valves, the most common type of valve in the industry, are valves that open by lifting a gate out of the route of the fluid. Gate valves are designed to be fully open or closed; they are regularly used as a block valve for isolating pipe systems.
When a gate valve is open, there is no obstruction in the flow path resulting in very little friction loss. Gate valves are used when a straight-line flow of fluid and minimum restriction is desired.
These can be controlled by a hand-wheel, air powered diaphragm, electric motor, or a piston actuator.
Globe valves are used for regulating flow in a pipeline, instead of having the “all or nothing” function of a gate valve. Globe valves regulate by the position of a movable disk (or plug) in relation with the stationary ring seat.
A globe valve may have ports that run straight across, or may be pointed at an angle. This type of angled supply valve is commonly used for corrosive or thick, viscous fluids that tend to solidify. Having outlets on anthat point downward helps the fluid to drain off to prevent clogging and corrosion.