Gas Orifice Flow Calculator

Gas Flow Rate Formula:

\[ Q = C_d \times A \times \sqrt{\frac{2 \times \Delta P}{\rho_g}} \times 448.83 \]

Discharge Coefficient (C_d):

Orifice Area (A):

ft²

Pressure Drop (ΔP):

psi

Gas Density (ρ_g):

lb/ft³

Flow Rate (Q): GPM

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1. What is a Gas Orifice Flow Calculator?

Definition: This calculator estimates the volumetric flow rate of gas through an orifice in GPM (gallons per minute equivalent).

Purpose: It helps engineers and technicians determine gas flow rates for system design, analysis, and troubleshooting.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Q = C_d \times A \times \sqrt{\frac{2 \times \Delta P}{\rho_g}} \times 448.83 \]

Where:

\( Q \) — Flow rate (GPM)
\( C_d \) — Discharge coefficient (dimensionless, typically 0.6-0.7)
\( A \) — Orifice area (ft²)
\( \Delta P \) — Pressure drop across orifice (psi)
\( \rho_g \) — Gas density (lb/ft³)

Explanation: The formula calculates theoretical flow, adjusted by the discharge coefficient and converted to GPM.

3. Importance of Orifice Flow Calculation

Details: Accurate flow calculations are essential for proper system design, safety, and performance optimization in gas systems.

4. Using the Calculator

Tips: Enter the discharge coefficient (default 0.62), orifice area in square feet, pressure drop in psi, and gas density (default 0.075 lb/ft³ for air at STP).

5. Frequently Asked Questions (FAQ)

Q1: What is the discharge coefficient?
A: It's a dimensionless factor (0-1) that accounts for flow losses through the orifice. Typical values range from 0.6 to 0.7.

Q2: Why is the result in GPM for gas flow?
A: The 448.83 factor converts the result to GPM equivalent for easier comparison with liquid flows.

Q3: What's a typical gas density value?
A: Air at standard conditions is 0.075 lb/ft³. Natural gas is about 0.045 lb/ft³.

Q4: How do I calculate orifice area?
A: For circular orifices, A = π × (diameter/2)². Convert to square feet (1 ft² = 144 in²).

Q5: What are the limitations of this calculation?
A: This assumes incompressible flow. For high pressure drops (>10% of inlet pressure), more complex compressible flow equations are needed.