Wildfire Knowledge Graph · Water Systems
Internal hose dimension that strongly affects velocity and friction loss for a given flow rate.
In plain language
Internal hose dimension that strongly affects velocity and friction loss for a given flow rate.
Why it matters
Hose Diameter is useful because it separates one specific part of wildfire behaviour, exposure, operations or evidence from nearby concepts that can otherwise be mixed together.
Hose diameter: an engineering example
Two hoses with the same internal diameter do not automatically deliver the same flow: elevation change, bends, fittings, length, nozzle pressure and supply pressure also matter. The important diameter is the internal dimension, not the nominal hose size printed on packaging.
For water flowing through a line under conditions where the Hazen–Williams approximation is appropriate, predicted friction head loss varies approximately with the inverse 4.87th power of inside diameter, when length, flow and roughness coefficient are unchanged. This is why a seemingly small diameter restriction can cause a large pressure penalty. This scaling is a comparison, not a complete design equation.
Worked comparison: at otherwise identical conditions, a hose whose internal diameter is 20% smaller (0.8 times the original) has a predicted friction loss about 3 times as large (1 / 0.8^4.87 ≈ 2.96). Before selecting a pump or firefighting hose, check the approved manufacturer rating, allowable pressure, actual geometry, flow and operational standards.
For the full system see Total Dynamic Head and Pump Sizing Calculator.