1. What is a PSI vs PSIG Calculator?

Definition: This calculator converts between PSIG (gauge pressure) and PSIA (absolute pressure) by adding atmospheric pressure (14.7 psi at sea level).

Purpose: It helps engineers, technicians, and students understand and convert between different pressure measurements used in various systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

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

Explanation: Gauge pressure measures pressure relative to atmospheric pressure, while absolute pressure includes atmospheric pressure.

3. Importance of Pressure Conversion

Details: Proper pressure conversion is essential for accurate system design, safety calculations, and equipment specification in HVAC, industrial processes, and aerospace applications.

4. Using the Calculator

Tips: Simply enter the PSIG value to get the corresponding PSIA value. The calculation assumes standard atmospheric pressure (14.7 psi).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between PSI, PSIG, and PSIA?
A: PSI is a general term for pressure. PSIG is gauge pressure (relative to atmosphere). PSIA is absolute pressure (including atmospheric pressure).

Q2: Why is 14.7 psi used in the formula?
A: This is standard atmospheric pressure at sea level. Actual atmospheric pressure varies with altitude and weather conditions.

Q3: How does altitude affect the conversion?
A: At higher altitudes, atmospheric pressure decreases. For precise calculations at altitude, use the local atmospheric pressure instead of 14.7 psi.

Q4: Can this calculator convert PSIA to PSIG?
A: Yes, simply rearrange the formula: PSIG = PSIA - 14.7.

Q5: When would I need to use PSIA instead of PSIG?
A: PSIA is used in scientific calculations, vacuum systems, and anywhere the absolute pressure is needed rather than pressure relative to atmosphere.