Air Flow Through Orifice Calculator

Air 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 Difference (ΔP):

psi

Gas Density (ρ_g):

lb/ft³

Air Flow Rate (Q): GPM

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1. What is an Air Flow Through 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 pneumatic systems, ventilation, and fluid dynamics applications.

2. How Does the Calculator Work?

The calculator uses the formula:

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

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)
\( \rho_g \) — Gas density (pounds per cubic foot)

Explanation: The formula calculates the theoretical flow rate adjusted by the discharge coefficient to account for real-world conditions.

3. Importance of Air Flow Calculation

Details: Accurate air flow calculations are essential for system design, efficiency analysis, and troubleshooting in HVAC, pneumatic systems, and industrial processes.

4. Using the Calculator

Tips: Enter the discharge coefficient (default 0.62 for sharp-edged orifice), orifice area, pressure difference, and gas density (default 0.075 lb/ft³ for air at STP). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the discharge coefficient (C_d)?
A: It's a dimensionless factor that accounts for flow losses through the orifice, typically ranging from 0.6 to 0.9 depending on orifice geometry.

Q2: Why is the result in GPM when calculating air flow?
A: The 448.83 factor converts the result to gallons per minute equivalent for practical applications, though the actual medium is air.

Q3: What's a typical gas density for air?
A: At standard conditions (68°F, 1 atm), air density is about 0.075 lb/ft³, but this varies with temperature and pressure.

Q4: How do I calculate orifice area?
A: For circular orifices, use \( A = \pi \times (d/2)^2 \) where d is diameter in feet.

Q5: Does this work for other gases?
A: Yes, but you must use the correct density for your specific gas at operating conditions.