Which type of valves are used for straight-line flow and minimum restriction?

The type of valve that is designed for straight-line flow with minimum restriction is the gate valve. Gate valves are specifically engineered to provide a straight path for fluid movement, allowing for minimal resistance and pressure drop when fully opened. This design is beneficial in applications where the fluid flow needs to remain unobstructed, such as in pipelines where maximum flow is desired.

When a gate valve is fully opened, the gate mechanism is raised, enabling fluid to flow uninterrupted, which is crucial in situations requiring high flow rates and minimal turbulence. This feature distinguishes gate valves from other types, which may create more resistance or have limitations in flow control.

The other types of valves mentioned can restrict flow to varying degrees. For instance, while ball valves also facilitate good flow characteristics, they may not be as effective in certain large-diameter applications where gate valves excel. Butterfly valves are typically used for throttling and can have some flow restrictions when partially open. Check valves are designed primarily to prevent backflow, rather than to provide straightforward flow control.