Fire Hose Flow Rate Calculator

Flow Rate Formula:

\[ Q = C_d \times A \times \sqrt{\frac{2 \times \Delta P}{\rho}} \times 448.83 \]

Discharge Coefficient (C_d):

Nozzle Area (A):

ft²

Pressure Difference (ΔP):

psi

Fluid Density (ρ):

lb/ft³

Flow Rate (Q): GPM

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1. What is a Fire Hose Flow Rate Calculator?

Definition: This calculator estimates the flow rate of water through a fire hose nozzle in gallons per minute (GPM) based on nozzle characteristics and pressure.

Purpose: It helps firefighters and fire safety professionals determine water flow rates for effective fire suppression.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Q = C_d \times A \times \sqrt{\frac{2 \times \Delta P}{\rho}} \times 448.83 \]

Where:

\( Q \) — Flow rate (gallons per minute)
\( C_d \) — Discharge coefficient (dimensionless, ~0.97 for smooth nozzles)
\( A \) — Nozzle area (square feet)
\( \Delta P \) — Pressure difference across nozzle (psi)
\( \rho \) — Fluid density (pounds per cubic foot)

Explanation: The formula calculates theoretical flow rate adjusted by the discharge coefficient to account for real-world nozzle inefficiencies.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate estimation ensures proper water delivery for fire suppression, helps select appropriate pump sizes, and maintains safe operating pressures.

4. Using the Calculator

Tips: Enter the discharge coefficient (default 0.97), nozzle area in ft², pressure difference in psi, and fluid density (default 62.4 lb/ft³ for water). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical discharge coefficient for fire nozzles?
A: Most smooth-bore nozzles have C_d between 0.95-0.99, while fog nozzles typically range 0.75-0.90.

Q2: How do I calculate nozzle area?
A: For circular nozzles, A = π × (diameter/2)². Convert diameter to feet for this calculation.

Q3: Why is the conversion factor 448.83 used?
A: This converts the result from cubic feet per second to gallons per minute (1 ft³/s = 448.83 GPM).

Q4: What affects the discharge coefficient?
A: Nozzle design, interior smoothness, and flow conditions all impact C_d.

Q5: How does pressure affect flow rate?
A: Flow rate increases with the square root of pressure, so doubling pressure increases flow by about 41%.