Water Pressure vs Flow Rate Calculator

Flow Rate Formulas:

\[ V = \sqrt{\frac{2 \times (P_1 - P_2) \times 144}{\rho}} \]
\[ Q = V \times A \times 448.83 \]

Inlet Pressure (P₁):

psi

Outlet Pressure (P₂):

psi

Fluid Density (ρ):

lb/ft³

Pipe Area (A):

ft²

Velocity (V): ft/s

Flow Rate (Q): GPM

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1. What is a Water Pressure vs Flow Rate Calculator?

Definition: This calculator determines water flow rate through a pipe based on pressure difference and pipe cross-sectional area.

Purpose: It helps engineers, plumbers, and irrigation specialists design and analyze fluid systems.

2. How Does the Calculator Work?

The calculator uses these formulas:

\[ V = \sqrt{\frac{2 \times (P_1 - P_2) \times 144}{\rho}} \]
\[ Q = V \times A \times 448.83 \]

Where:

\( V \) — Velocity (feet per second)
\( P_1 \) — Inlet pressure (psi)
\( P_2 \) — Outlet pressure (psi)
\( \rho \) — Fluid density (pounds per cubic foot)
\( Q \) — Flow rate (gallons per minute)
\( A \) — Pipe cross-sectional area (square feet)

Explanation: The pressure difference creates flow velocity, which when multiplied by pipe area gives volumetric flow rate.

3. Importance of Pressure-Flow Calculations

Details: Accurate flow rate prediction ensures proper system design, prevents pipe oversizing/undersizing, and helps optimize pump selection.

4. Using the Calculator

Tips: Enter pressure values (psi), fluid density (default 62.4 lb/ft³ for water), and pipe area (ft²). All values must be > 0 except outlet pressure which can be 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the 144 factor in the equation?
A: This converts psi (lb/in²) to lb/ft² (1 ft² = 144 in²).

Q2: Why 448.83 in the flow rate formula?
A: This converts ft³/s to GPM (1 ft³/s = 448.83 GPM).

Q3: What's a typical water density value?
A: Pure water at 60°F is 62.4 lb/ft³. Adjust for temperature or other fluids.

Q4: How do I find pipe area?
A: For circular pipes: \( A = \pi \times (D/2)^2 \) where D is diameter in feet.

Q5: Does this account for friction losses?
A: No, this is ideal flow. For real systems, use Darcy-Weisbach or Hazen-Williams equations.