1. What is PSI to PSIG Conversion?

PSI (Pounds per Square Inch) to PSIG (Pounds per Square Inch Gauge) conversion is the process of converting absolute pressure to gauge pressure by subtracting atmospheric pressure. Gauge pressure represents pressure relative to atmospheric pressure.

2. How Does the Calculator Work?

The calculator uses the PSIG conversion formula:

Where:

• \( PSIG \) — Gauge pressure (psig)
• \( PSI \) — Absolute pressure (psi)
• \( P_{atm} \) — Atmospheric pressure (psi)

Explanation: Standard atmospheric pressure at sea level is approximately 14.7 psi. Gauge pressure is the pressure measured relative to atmospheric pressure.

3. Importance of Pressure Conversion

Details: Understanding the difference between absolute and gauge pressure is crucial in various engineering applications, including HVAC systems, pneumatic controls, pressure vessel design, and industrial processes where pressure measurements are critical.

4. Using the Calculator

Tips: Enter absolute PSI value and atmospheric pressure (default is 14.7 psi for sea level). For locations at different altitudes, adjust atmospheric pressure accordingly.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between PSI and PSIG?
A: PSI refers to absolute pressure (including atmospheric pressure), while PSIG is gauge pressure (excluding atmospheric pressure).

Q2: Why is atmospheric pressure 14.7 psi at sea level?
A: This is the standard atmospheric pressure due to the weight of the air column above sea level. It decreases with increasing altitude.

Q3: When should I use PSIG vs PSI?
A: Use PSIG for most pressure gauge readings and industrial applications. Use PSI (absolute) for scientific calculations and vacuum measurements.

Q4: How does altitude affect the conversion?
A: At higher altitudes, atmospheric pressure decreases, so the conversion factor becomes smaller than 14.7 psi.

Q5: Can PSIG be negative?
A: Yes, negative PSIG indicates vacuum or pressure below atmospheric pressure.