Question 1

What is gauge vs absolute pressure?

Accepted Answer

Gauge = above atmospheric. Absolute = total pressure. 0 PSIG = 14.7 PSIA (sea level). Vacuum is negative gauge.

Question 2

When do I use absolute vs gauge pressure?

Accepted Answer

Gauge for tires, blood pressure. Absolute for thermodynamics, gas laws, vacuum systems.

Question 3

What pressure units do different industries use?

Accepted Answer

PSI in US/UK automotive and HVAC. Bar/kPa in European engineering. mmHg/torr in medicine. Atmospheres in diving and altitude.

Question 4

Is gauge pressure different from absolute pressure?

Accepted Answer

Yes! Gauge pressure reads 0 at atmospheric pressure. Absolute pressure adds atmospheric (~14.7 psi). Vacuum gauge shows negative gauge pressure.

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