1. What is PSI and PSIG?

PSI (Pounds per Square Inch) is a unit of pressure. PSIG (Pounds per Square Inch Gauge) measures pressure relative to atmospheric pressure, while absolute PSI measures pressure relative to a perfect vacuum.

2. How Does the Calculator Work?

The calculator uses the pressure conversion formula:

Where:

• \( PSI_{absolute} \) — Absolute pressure in psi
• \( PSI_{gauge} \) — Gauge pressure reading in psi
• \( Atmospheric\ Pressure \) — Standard atmospheric pressure (14.7 psi at sea level)

Explanation: Gauge pressure measures pressure above atmospheric pressure, so adding atmospheric pressure gives the absolute pressure value.

3. Importance of Pressure Conversion

Details: Accurate pressure conversion is crucial for engineering calculations, fluid dynamics, HVAC systems, and scientific research where absolute pressure values are required.

4. Using the Calculator

Tips: Enter the gauge pressure reading in psi and the atmospheric pressure (default is 14.7 psi for sea level). For different altitudes, adjust the atmospheric pressure accordingly.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between PSI and PSIG?
A: PSI can refer to either absolute or gauge pressure, while PSIG specifically means gauge pressure (pressure above atmospheric).

Q2: Why is atmospheric pressure 14.7 psi?
A: This is the standard atmospheric pressure at sea level. Atmospheric pressure decreases with increasing altitude.

Q3: When should I use absolute vs gauge pressure?
A: Use absolute pressure for scientific calculations, vacuum systems, and gas laws. Use gauge pressure for most industrial and mechanical applications.

Q4: How does altitude affect the conversion?
A: At higher altitudes, atmospheric pressure is lower than 14.7 psi, so the conversion factor should be adjusted accordingly.

Q5: Can this calculator be used for negative gauge pressures?
A: Yes, the calculator works for vacuum pressures (negative PSIG values) as well.