1. What is a PSIA to PSIG Calculator?

Definition: This calculator converts absolute pressure (PSIA) to gauge pressure (PSIG) by subtracting atmospheric pressure.

Purpose: It helps engineers, technicians, and students working with pressure measurements to easily convert between absolute and gauge pressure units.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

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

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

3. Importance of PSIA-PSIG Conversion

Details: Proper pressure conversion is essential for accurate measurements in HVAC systems, industrial processes, and scientific applications where pressure readings are critical.

4. Using the Calculator

Tips: Simply enter the absolute pressure value in PSIA. The calculator will automatically subtract standard atmospheric pressure (14.7 psi) to give you the equivalent gauge pressure.

5. Frequently Asked Questions (FAQ)

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

Q2: Can PSIG be negative?
A: Yes, when PSIA is less than 14.7, PSIG will be negative, indicating a vacuum or pressure below atmospheric.

Q3: What's the difference between PSIA and PSIG?
A: PSIA measures pressure relative to a perfect vacuum, while PSIG measures pressure relative to atmospheric pressure.

Q4: When would I need to make this conversion?
A: When working with pressure gauges (which typically show PSIG) or when using equations that require absolute pressure values.

Q5: How does altitude affect this calculation?
A: At higher altitudes, atmospheric pressure is less than 14.7 psi. For precise work, use local atmospheric pressure instead of 14.7.