1. What is a Low Pressure Hydrant Flow Calculator?

Definition: This calculator estimates the flow rate from a hydrant based on the nozzle coefficient and water pressure.

Purpose: It helps fire protection professionals and engineers determine water flow rates for firefighting and hydraulic calculations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gallons per minute, gpm)
• \( C \) — Nozzle coefficient (dimensionless)
• \( P \) — Pressure (psi)

Explanation: The flow rate is proportional to the square root of the pressure, with the nozzle coefficient accounting for nozzle characteristics.

3. Importance of Hydrant Flow Calculation

Details: Accurate flow rate estimation ensures adequate water supply for firefighting and proper system design.

4. Using the Calculator

Tips: Enter the nozzle coefficient (default 29.83 for standard hydrants) and pressure in psi. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical nozzle coefficient?
A: Standard hydrants typically have coefficients between 29.83 and 30, but this varies by manufacturer and nozzle type.

Q2: Why does flow depend on the square root of pressure?
A: This relationship comes from the Bernoulli equation and conservation of energy in fluid dynamics.

Q3: When would I need to change the coefficient?
A: Use different coefficients for specialized nozzles or when manufacturer specifications differ from standard values.

Q4: What pressure range is this calculator valid for?
A: This calculation is valid for low to moderate pressure ranges typically found in municipal water systems (20-100 psi).

Q5: Does this account for friction loss?
A: No, this is the theoretical flow at the nozzle. For system design, you must account for friction loss in pipes.