Air Pressure Flow Rate Calculator

Air Flow Rate Formulas:

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

Inlet Pressure (P₁):

psi

Outlet Pressure (P₂):

psi

Air Density (ρ):

lb/ft³

Flow Area (A):

ft²

Velocity (V): ft/s

Flow Rate (Q): GPM

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1. What is an Air Pressure Flow Rate Calculator?

Definition: This calculator determines air flow rate in GPM equivalent based on pressure difference, air density, and flow area.

Purpose: It helps engineers and technicians calculate air flow rates in systems where pressure differentials are known.

2. How Does the Calculator Work?

The calculator uses two formulas:

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

Where:

\( V \) — Velocity (feet per second)
\( P_1 \) — Inlet pressure (psi)
\( P_2 \) — Outlet pressure (psi)
\( \rho \) — Air density (pounds per cubic foot)
\( Q \) — Flow rate (gallons per minute equivalent)
\( A \) — Flow area (square feet)

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

3. Importance of Air Flow Rate Calculation

Details: Accurate flow rate calculations are essential for HVAC system design, pneumatic system analysis, and industrial process control.

4. Using the Calculator

Tips: Enter the pressure values (P₁ and P₂), air density (default 0.0749 lb/ft³ for standard air), and flow area. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: Why is there a 144 in the formula?
A: This converts psi (lb/in²) to lb/ft² (since 1 ft² = 144 in²).

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

Q3: What's typical air density at sea level?
A: Standard air density is 0.0749 lb/ft³ at 70°F and sea level.

Q4: How do I measure flow area?
A: For circular ducts, A = π × (diameter/2)². For rectangular ducts, A = width × height.

Q5: Does this account for compressibility?
A: This simplified formula works best for small pressure differences. For large ΔP, more complex formulas are needed.