1. What is Specific Gravity of Air?

Definition: Specific gravity (SG) of air is the ratio of the density of air to the density of water at standard conditions.

Purpose: This calculator converts the specific gravity of air to density in pounds per cubic foot (lb/ft³).

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \rho \) — Density of air (lb/ft³)
• \( SG \) — Specific gravity of air (unitless)
• 62.4 — Density of water (lb/ft³ at standard conditions)

Explanation: The specific gravity is multiplied by the density of water to obtain the air density.

3. Importance of Air Density Calculation

Details: Air density is crucial for HVAC design, aerodynamics calculations, buoyancy assessments, and various engineering applications.

4. Using the Calculator

Tips: Enter the specific gravity of air (default 0.0012 for standard conditions). The value must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the typical specific gravity of air?
A: At standard temperature and pressure (STP), air has a specific gravity of about 0.0012.

Q2: What's the standard air density at STP?
A: Approximately 0.075 lb/ft³ (which equals 0.0012 × 62.4).

Q3: When would the specific gravity change?
A: It varies with altitude, temperature, humidity, and atmospheric pressure.

Q4: Why is water density 62.4 lb/ft³?
A: This is the density of water at standard conditions (4°C, 1 atm pressure).

Q5: How does air density affect engineering calculations?
A: It impacts lift calculations, pressure drops in ducts, wind load calculations, and more.