Which type of valve should only be used when fully open or fully closed?

The gate valve is specifically designed for use in applications where it is either fully open or fully closed. This design allows for minimal pressure drop and disruption to the flow, making it unsuitable for throttling or regulating flow. When the gate valve is in the open position, it provides a clear, unobstructed path for the fluid, facilitating efficient flow. Conversely, when it is closed, it creates a tight seal, effectively halting the passage of fluid.

This characteristic makes gate valves ideal for on-off control in pipelines. They are commonly used in scenarios where flow need not be adjusted, such as in water supply systems or for isolating sections of a system during maintenance. In contrast, other types of valves like globe valves, reducing valves, and throttle valves are designed for flow regulation and modulation, which is not the intended use of a gate valve.