Which type of valve offers the least resistance to flow?

The gate valve is designed primarily for being fully opened or fully closed, which allows for an unobstructed passage through the valve when it is in the open position. This design minimizes turbulence and flow resistance, making it the most efficient choice for applications that require a straight-line flow without restrictions.

Unlike other types of valves, such as globe valves that have a more complex internal structure leading to significant flow resistance when open, or check valves that are meant to prevent backflow but can create turbulence, the gate valve does not impede the flow when fully opened. This characteristic makes the gate valve well-suited for applications where it is essential to maintain high flow rates, such as in large pipelines where fluid dynamics are important.

Additionally, ball valves, while also low in resistance when fully open, can have slightly more flow resistance compared to gate valves due to their spherical shape and the seal design. Therefore, for applications requiring minimal flow resistance, gate valves are often preferred.