Calculate Flow from Pressure

Flow Rate Formulas:

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

Upstream Pressure (P₁):

psi

Downstream Pressure (P₂):

psi

Fluid Density (ρ):

lb/ft³

Cross-sectional Area (A):

ft²

Velocity (V): ft/s

Flow Rate (Q): GPM

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1. What is Flow from Pressure Calculation?

Definition: This calculator determines the fluid velocity and volumetric flow rate through a pipe or orifice based on pressure difference and fluid properties.

Purpose: Essential for hydraulic system design, pipe sizing, and flow control applications in engineering and fluid mechanics.

2. How Does the Calculator Work?

The calculator uses two fundamental formulas:

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

Where:

\( V \) — Fluid velocity (feet/second)
\( P_1 \) — Upstream pressure (psi)
\( P_2 \) — Downstream pressure (psi)
\( \rho \) — Fluid density (pounds/cubic foot)
\( Q \) — Volumetric flow rate (gallons/minute)
\( A \) — Cross-sectional area (square feet)

Explanation: The first equation calculates velocity from pressure difference (converted to psf) and density. The second converts velocity to flow rate in GPM.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate prediction ensures proper system performance, prevents pipe erosion, and helps select appropriate pump sizes.

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 formula?
A: This converts psi to psf (pounds per square foot) since 1 psi = 144 psf.

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

Q3: When would I adjust the density value?
A: For fluids other than water (e.g., oil ρ≈55 lb/ft³, seawater ρ≈64 lb/ft³).

Q4: How do I find the cross-sectional area?
A: For circular pipes, A = π × (diameter/2)². Convert diameter to feet first.

Q5: Does this account for friction losses?
A: No, this is ideal flow. For real systems, consider additional head loss calculations.