1. What is PSI to PSIG Conversion?

The PSI to PSIG conversion calculates gauge pressure from absolute pressure by subtracting atmospheric pressure (14.7 psi). PSIA (absolute pressure) includes atmospheric pressure, while PSIG (gauge pressure) measures pressure relative to atmospheric pressure.

2. How Does the Calculator Work?

The calculator uses the PSIG formula:

Where:

• \( PSIG \) — Gauge pressure (pounds per square inch gauge)
• \( PSI \) — Absolute pressure (pounds per square inch absolute)
• \( 14.7 \) — Standard atmospheric pressure at sea level (psi)

Explanation: This conversion accounts for the atmospheric pressure that is always present, allowing measurement of pressure relative to the surrounding environment.

3. Importance of PSI/PSIG Distinction

Details: Understanding the difference between absolute and gauge pressure is crucial for accurate pressure measurements in various applications including industrial processes, HVAC systems, pneumatic controls, and scientific research.

4. Using the Calculator

Tips: Enter absolute PSI (psia) value in the input field. The value must be greater than 0. The calculator will automatically subtract 14.7 psi (standard atmospheric pressure) to provide the gauge pressure reading.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between PSI and PSIG?
A: PSI (absolute) includes atmospheric pressure, while PSIG (gauge) measures pressure relative to atmospheric pressure. PSIG = PSIA - 14.7.

Q2: Why is 14.7 psi used for atmospheric pressure?
A: 14.7 psi represents standard atmospheric pressure at sea level. This value may vary slightly with altitude and weather conditions.

Q3: When should I use PSIG vs PSIA?
A: Use PSIG for most pressure gauge readings (tires, compressed air systems). Use PSIA for scientific calculations, vacuum measurements, and applications requiring absolute pressure reference.

Q4: Can PSIG be negative?
A: Yes, PSIG can be negative when measuring vacuum or pressures below atmospheric pressure. Negative PSIG indicates a partial vacuum.

Q5: How does altitude affect this conversion?
A: At higher altitudes, atmospheric pressure decreases. For precise measurements at high altitudes, use the local atmospheric pressure instead of 14.7 psi.