Friction Loss

Hose Coefficient

Use a 100-foot flow test to estimate a hose's friction-loss coefficient.

What It Tells You

The coefficient that makes friction-loss calculations match a tested hose section.

Formula

C = FL ÷ (Q ÷ 100)²

What the Variables Mean

C
hose coefficient unitless
FL
pressure drop across 100 feet PSI
Q
test flow GPM

Plain-Language Explanation

A coefficient describes how much resistance a hose creates. A lower coefficient means less friction loss at the same flow.

Worked Example

A 100-foot section loses 53 PSI while flowing 185 GPM.

  1. C = 53 ÷ 1.85²
C ≈ 15.5

Fireground Takeaway

Department flow testing can replace generic assumptions with values that better match actual hose.

Practice This Formula

Open Reverse Flow and start a Practice Quiz filtered to this topic.

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