Calculate Gas Flow Rate from Pressure

Gas Flow Rate Formulas:

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

Upstream Pressure (P₁):

psi

Downstream Pressure (P₂):

psi

Gas Density (ρ_g):

lb/ft³

Cross-Sectional Area (A):

ft²

Gas Velocity (V): ft/s

Flow Rate (Q): GPM

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1. What is Gas Flow Rate from Pressure Calculator?

Definition: This calculator determines the gas flow rate in gallons per minute (GPM) based on pressure difference, gas density, and pipe cross-sectional area.

Purpose: It helps engineers and technicians calculate gas flow rates in piping systems for design and analysis purposes.

2. How Does the Calculator Work?

The calculator uses two formulas:

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

Where:

\( V \) — Gas velocity (feet per second)
\( P_1 \) — Upstream pressure (psi)
\( P_2 \) — Downstream pressure (psi)
\( \rho_g \) — Gas density (pounds per cubic foot)
\( Q \) — Flow rate (gallons per minute)
\( A \) — Cross-sectional area (square feet)

Explanation: The first equation calculates gas velocity from pressure difference, and the second converts velocity to volumetric flow rate.

3. Importance of Gas Flow Rate Calculation

Details: Accurate flow rate calculations are essential for proper system design, ensuring adequate gas supply, and maintaining safe operating conditions.

4. Using the Calculator

Tips: Enter upstream and downstream pressures in psi, gas density (default 0.075 lb/ft³ for air at STP), and pipe cross-sectional area. All values must be > 0 and P₁ > P₂.

5. Frequently Asked Questions (FAQ)

Q1: What units does this calculator use?
A: The calculator uses psi for pressure, lb/ft³ for density, ft² for area, ft/s for velocity, and GPM for flow rate.

Q2: What's a typical gas density value?
A: Air at standard conditions is about 0.075 lb/ft³. Other gases vary (e.g., natural gas ~0.045 lb/ft³).

Q3: How do I calculate pipe cross-sectional area?
A: For circular pipes, A = π × (diameter/2)² where diameter is in feet.

Q4: What's the 144 factor in the equation?
A: This converts psi to psf (pounds per square foot) since density is in lb/ft³.

Q5: What's the 448.83 conversion factor?
A: This converts ft³/s to GPM (gallons per minute).