LDH stands for what, and when is it used?

Answer: C — Large Diameter Hose; used to move large volumes of water in relay operations and long lays

Large Diameter Hose is designed to move big volumes of water over distance. It’s used in water supply operations, especially in relay setups and long lays, because the larger diameter allows more flow with less friction loss, making it possible to push water from the source to the fire scene efficiently. This makes it ideal for supplying pumpers and handling long runs. It isn’t used for interior attack work, like attic fires, where smaller, more portable handlines are preferred for maneuverability and rapid application. LDH is typically a larger-diameter supply hose (commonly in the 3–6 inch range) used specifically for delivering high water volumes rather than for direct fire attack.