Fire Academy Interior Attack Practice Test

Friction loss in a hose is driven by how fast the water must move through the line. For the same total flow, a smaller diameter hose forces a higher velocity, which increases friction against the hose interior and eats up more pressure before the nozzle. Conversely, a larger diameter hose lowers the velocity for the same flow, reducing friction loss and helping maintain nozzle pressure. If you can’t use one large hose, splitting the flow across multiple hoses achieves the same effect by reducing the flow (and thus velocity) in each hose, which lowers friction losses overall. Temperature changes have only a minor impact on friction loss in firefighting conditions, and shortening a hose helps a bit by reducing length, but it doesn’t address the practical need to deliver the required flow to reach the target. So the recommended approach to minimize friction loss is to use a larger diameter hose or multiple hoses.