The least head loss in a pipeline is created by a fully open ?

• A. Gate valve
• B. Check valve
• C. Globe valve
• D. Angle valve

Answer: (A)

Head loss from valves comes from the flow having to squeeze through the valve’s internal geometry. When a valve is fully open, you want the path to resemble the pipe itself as closely as possible, with minimal obstruction and turbulence.

A fully open gate valve provides the straightest, least obstructed path among common valve types. The gate retracts completely out of the flow, leaving a bore nearly identical to the pipe, so friction loss is mainly the pipe’s own, not the valve. In contrast, a globe valve uses a plug and seat that create a throttling path even when the valve is open, adding extra resistance and increasing head loss. An angle valve redirects flow at a bend, which introduces additional turbulence and a larger pressure drop than a straight-through path. A check valve has a movable disk that can cause a local restriction and flow-induced disturbances; although it’s designed to prevent backflow, the flow still experiences some loss as it passes the valve.

So, the least head loss is produced by a fully open gate valve.