1. What is the Pressure vs Flow Rate Equation?

Definition: These equations relate fluid pressure differential to velocity and volumetric flow rate in a pipe or conduit.

Purpose: Used in fluid dynamics to calculate flow characteristics in piping systems, hydraulics, and process engineering.

2. How Do the Equations Work?

The calculator uses two equations:

Where:

• \( V \) — Fluid velocity (ft/s)
• \( P_1 \) — Inlet pressure (psi)
• \( P_2 \) — Outlet pressure (psi)
• \( \rho \) — Fluid density (lb/ft³)
• \( Q \) — Volumetric flow rate (GPM)
• \( A \) — Cross-sectional area (ft²)

Explanation: The first equation calculates velocity from pressure differential, while the second converts velocity to flow rate.

3. Importance of Pressure-Flow Calculations

Details: Accurate calculations ensure proper system design, pump sizing, and verification of flow requirements in piping systems.

4. Using the Calculator

Tips: Enter pressure values (P₁ > P₂), fluid density (default 62.4 lb/ft³ for water), and cross-sectional area. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: Why is there a 144 in the equation?
A: This converts psi to lb/ft² (1 psi = 144 lb/ft²) for consistent units in the calculation.

Q2: What's the 448.83 conversion factor?
A: This converts ft³/s to gallons per minute (1 ft³/s = 448.83 GPM).

Q3: What density should I use for other fluids?
A: Use actual density - 49.2 lb/ft³ for gasoline, 78.6 lb/ft³ for seawater, etc.

Q4: Does this account for friction losses?
A: No, this is for ideal flow. For real systems, include friction factors and pipe roughness.

Q5: How do I calculate cross-sectional area?
A: For circular pipes: \( A = \pi \times (diameter/2)^2 \) (convert diameter to feet).