Nozzles & Equipment
Large Diameter Hose
LDH
Large diameter hose is wide supply hose used to move big volumes of water with very little friction loss. Its size is what lets an engine pull a strong supply over a long distance.
Friction loss falls sharply as diameter grows, so large diameter hose can carry a high flow while giving up only a little pressure per length. That makes it the workhorse for hydrant-to-pumper supply and for relays.
The trade-off is weight, water capacity, and handling. A charged large line holds a lot of water and is hard to move, so it is laid as supply rather than worked as an attack line.
Where this shows up
Calculator
Friction LossCalculator
Relay Pumping