How To Calculate Friction Loss In Fire Hose

Friction Loss Formula:

\[ FL = C \times \left(\frac{GPM}{100}\right)^2 \times \left(\frac{L}{100}\right) \]

Friction Loss (FL):

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1. What is Friction Loss in Fire Hose?

Friction loss in fire hose refers to the pressure loss that occurs as water flows through the hose due to the frictional resistance between the water and the hose interior. This calculation is essential for determining the required pump pressure to deliver adequate water flow at the nozzle.

2. How Does the Calculator Work?

The calculator uses the friction loss formula:

\[ FL = C \times \left(\frac{GPM}{100}\right)^2 \times \left(\frac{L}{100}\right) \]

Where:

\( FL \) — Friction loss (psi)
\( C \) — Coefficient (depends on hose diameter and type)
\( GPM \) — Flow rate (gallons per minute)
\( L \) — Hose length (feet)

Explanation: The formula calculates pressure loss based on the square of flow rate and directly proportional to hose length, with the coefficient accounting for hose characteristics.

3. Importance of Friction Loss Calculation

Details: Accurate friction loss calculation is crucial for firefighting operations to ensure proper water delivery, determine appropriate pump pressures, and maintain effective fire suppression capabilities.

4. Using the Calculator

Tips: Enter the hose coefficient (C), flow rate in GPM, and hose length in feet. All values must be positive numbers for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What are typical coefficient values for fire hoses?
A: Coefficient values vary by hose diameter: 1.75" hose: C=15.5, 2.5" hose: C=2.0, 3" hose: C=0.8, 4" hose: C=0.2

Q2: Why does friction loss increase with the square of flow rate?
A: Friction loss increases exponentially with flow rate because higher velocities create more turbulent flow and greater frictional resistance.

Q3: How does hose length affect friction loss?
A: Friction loss is directly proportional to hose length - doubling the hose length doubles the friction loss at the same flow rate.

Q4: What factors influence the coefficient value?
A: Hose diameter, interior lining material, age, and condition all affect the coefficient value. Newer hoses typically have lower coefficients.

Q5: How accurate is this calculation for real-world applications?
A: While the formula provides a good estimate, actual field conditions such as hose age, temperature, and water additives may affect results. Always include a safety margin.