Which factor is not a significant factor in calculating friction loss?

Which factor is not a significant factor in calculating friction loss?

• A. Pipe Length
• B. GPM
• C. Pipe Diameter
• D. Water Temperature

Answer: (D)

Friction loss is driven by how much water you’re moving, through what size hose, and how long that hose run is. Pushing more water (higher GPM) increases the shear and resistance along the pipe walls, so friction loss goes up. A smaller diameter hose has a higher velocity for the same flow, which also raises friction. And a longer hose run provides more surface contact and more resistance overall, increasing friction loss. These relationships are what the standard friction loss formulas (like Hazen-Williams or Darcy-Weisbach) are built on. Water temperature, while it does affect water’s viscosity and density in theory, is not included in these common calculations and does not produce a meaningful change within typical firefighting conditions. That’s why water temperature is not treated as a significant factor in estimating friction loss for fire operations.

Friction loss is driven by how much water you’re moving, through what size hose, and how long that hose run is. Pushing more water (higher GPM) increases the shear and resistance along the pipe walls, so friction loss goes up. A smaller diameter hose has a higher velocity for the same flow, which also raises friction. And a longer hose run provides more surface contact and more resistance overall, increasing friction loss. These relationships are what the standard friction loss formulas (like Hazen-Williams or Darcy-Weisbach) are built on.

Water temperature, while it does affect water’s viscosity and density in theory, is not included in these common calculations and does not produce a meaningful change within typical firefighting conditions. That’s why water temperature is not treated as a significant factor in estimating friction loss for fire operations.