1. What is PSI to PSIA Conversion?

PSIA (pounds per square inch absolute) is the pressure measurement relative to a perfect vacuum. PSI (pounds per square inch gauge) measures pressure relative to atmospheric pressure. The conversion accounts for atmospheric pressure at sea level (14.7 psi).

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( PSI \) — Gauge pressure (relative to atmospheric)
• \( 14.7 \) — Standard atmospheric pressure at sea level (psi)

Explanation: Absolute pressure includes the atmospheric pressure that exists at sea level, while gauge pressure measures only the pressure above atmospheric.

3. Importance of Absolute Pressure

Details: Absolute pressure measurements are essential for scientific calculations, thermodynamics, and applications where the complete pressure environment must be considered, rather than just the pressure relative to the surrounding atmosphere.

4. Using the Calculator

Tips: Simply enter the gauge pressure in PSI (must be ≥0) and the calculator will add 14.7 psi to convert to absolute pressure.

5. Frequently Asked Questions (FAQ)

Q1: Why is 14.7 psi used for atmospheric pressure?
A: This is the standard atmospheric pressure at sea level. Actual atmospheric pressure varies with altitude and weather conditions.

Q2: When should I use PSIA vs PSIG?
A: Use PSIA for scientific calculations and thermodynamics. Use PSIG for most industrial and engineering applications where only the pressure above atmosphere matters.

Q3: Does this conversion change with altitude?
A: Yes, atmospheric pressure decreases with altitude. The 14.7 psi standard is only accurate at sea level.

Q4: What's the difference between PSIA and PSIG?
A: PSIG is gauge pressure (relative to atmosphere), PSIA is absolute pressure (relative to perfect vacuum). PSIA = PSIG + atmospheric pressure.

Q5: Can PSIG be negative?
A: Yes, negative PSIG represents a vacuum (pressure below atmospheric).