Air Flow Rate Through an Orifice Calculator

Air Flow Rate Formula:

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

Discharge Coefficient (C_d):

Orifice Area (A):

ft²

Pressure Difference (ΔP):

psi

Fluid Density (ρ):

lb/ft³

Flow Rate (Q): GPM

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1. What is an Air Flow Rate Through an Orifice Calculator?

Definition: This calculator estimates the volumetric flow rate of air through an orifice based on the orifice characteristics and pressure difference.

Purpose: It helps engineers and technicians determine air flow rates in ventilation systems, pneumatic controls, and fluid dynamics applications.

2. How Does the Calculator Work?

The calculator uses the formula:

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

Where:

\( Q \) — Volumetric flow rate (gallons per minute equivalent)
\( C_d \) — Discharge coefficient (dimensionless, typically 0.6-0.65)
\( A \) — Cross-sectional area of the orifice (square feet)
\( \Delta P \) — Pressure difference across orifice (psi)
\( \rho \) — Fluid density (pounds per cubic foot)

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

3. Importance of Air Flow Rate Calculation

Details: Accurate flow rate calculations are essential for system design, performance evaluation, and troubleshooting in HVAC, industrial processes, and aerodynamics.

4. Using the Calculator

Tips: Enter the discharge coefficient (default 0.62), orifice area in square feet, pressure difference in psi, and fluid density (default 0.075 lb/ft³ for air at STP). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical discharge coefficient value?
A: For sharp-edged orifices, typical values range from 0.6 to 0.65. The default 0.62 is a common average.

Q2: Why is the result in GPM when calculating air flow?
A: The formula provides equivalent volumetric flow rate in gallons per minute for comparison with liquid flow systems.

Q3: How do I calculate orifice area?
A: For circular orifices, use \( A = \pi \times r^2 \) where r is the radius in feet.

Q4: What affects the discharge coefficient?
A: Orifice shape, edge sharpness, Reynolds number, and the ratio of orifice to pipe diameter.

Q5: Can I use this for other gases?
A: Yes, but you must adjust the density value (ρ) for the specific gas at operating conditions.