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PSIG to PSIA Formula:
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PSIA (Pounds per Square Inch Absolute) and PSIG (Pounds per Square Inch Gauge) are two different pressure measurement scales. PSIA measures pressure relative to absolute vacuum, while PSIG measures pressure relative to atmospheric pressure.
The calculator uses the conversion formula:
Where:
Explanation: This formula converts absolute pressure to gauge pressure by subtracting the standard atmospheric pressure.
Details: Understanding the difference between absolute and gauge pressure is crucial in various engineering applications, including HVAC systems, pneumatic controls, hydraulic systems, and industrial processes where accurate pressure measurements are essential for safety and efficiency.
Tips: Enter the absolute pressure value in PSIA. The calculator will automatically compute and display the corresponding gauge pressure in PSIG. All values must be valid positive numbers.
Q1: What is the difference between PSIA and PSIG?
A: PSIA measures pressure relative to absolute zero (perfect vacuum), while PSIG measures pressure relative to atmospheric pressure. PSIG = PSIA - atmospheric pressure.
Q2: Why is 14.7 psi used as atmospheric pressure?
A: 14.7 psi is the standard atmospheric pressure at sea level. Actual atmospheric pressure can vary with altitude and weather conditions.
Q3: When should I use PSIA vs PSIG?
A: Use PSIA for scientific calculations involving gas laws and thermodynamics. Use PSIG for most industrial and mechanical applications where pressure is measured relative to atmospheric pressure.
Q4: Can PSIG be negative?
A: Yes, PSIG can be negative when the absolute pressure is less than atmospheric pressure, indicating a vacuum or suction condition.
Q5: How does altitude affect the conversion?
A: At higher altitudes, atmospheric pressure decreases below 14.7 psi, so the conversion factor would be smaller. This calculator uses sea-level standard pressure.