1. What is Mass Flow Rate of Air?

Definition: This calculator determines the mass flow rate of air based on volumetric flow rate and air density.

Purpose: It helps engineers and technicians in HVAC, pneumatic systems, and process engineering calculate the mass of air moving through a system per hour.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( W \) — Mass flow rate (lb/hr)
• \( Q \) — Volumetric flow rate (GPM)
• \( \rho_{air} \) — Air density (lb/ft³, default 0.561)
• \( 60 \) — Conversion factor (minutes to hours)

Explanation: The volumetric flow rate is multiplied by air density to get mass per minute, then converted to hourly rate.

3. Importance of Mass Flow Rate Calculation

Details: Accurate mass flow rate calculations are essential for system design, energy calculations, and process control in air handling systems.

4. Using the Calculator

Tips: Enter the volumetric flow rate in GPM and air density (default 0.561 lb/ft³). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the standard air density value?
A: At standard conditions (68°F, 14.7 psi), air density is ~0.075 lb/ft³. The default 0.561 accounts for conversion from ft³ to gallons (×7.481).

Q2: Why multiply by 60?
A: This converts the flow rate from per-minute to per-hour basis (60 minutes in an hour).

Q3: When would I change the air density value?
A: Adjust for different temperatures, pressures, or altitudes where air density differs from standard conditions.

Q4: How do I find the volumetric flow rate?
A: Measure using flow meters or calculate from system parameters (duct velocity × cross-sectional area).

Q5: Can this be used for other gases?
A: Yes, but you must use the correct density value for the specific gas being measured.