Which valve is a common type with the least flow resistance?

The common type of valve that exhibits the least flow resistance is the gate valve. This valve is specifically designed to provide a straight-line flow of fluid with minimal obstruction, allowing for maximum flow efficiency. When fully opened, the gate valve has direct flow pathways that significantly reduce friction and turbulence compared to other valve types.

In contrast, swing check valves are designed primarily to prevent backflow and often include a mechanism that creates additional flow resistance when the fluid is moving past the disc. Globe valves, while excellent for throttling and controlling flow, have significant flow restriction due to their design and the shape of their internal passages. Ball valves provide good flow characteristics and can be nearly unobstructed, but typically they do not perform as well in terms of resistance as gate valves when fully opened.

Overall, for applications where low flow resistance is a priority, the gate valve stands out as the most effective choice, allowing for smooth, uninterrupted flow.