Which option best represents a gauge pressure unit?

Which option best represents a gauge pressure unit?

• A. PSIA
• B. Hg
• C. Pa
• D. PSIG

Answer: (D)

Gauge pressure shows how much pressure a system has above the surrounding atmosphere. The unit that represents this directly is pounds per square inch gauge, PSIG. It indicates pressure relative to ambient air, which is what you’re typically concerned with in refrigeration system pressures. Absolute pressure (PSIA) includes atmospheric pressure in the measurement, giving total pressure rather than just what’s above ambient. Pascals (Pa) are a general pressure unit, but without specifying gauge or absolute. Inches of mercury (Hg) is a traditional unit for pressure that isn’t inherently gauge-focused.

Gauge pressure shows how much pressure a system has above the surrounding atmosphere. The unit that represents this directly is pounds per square inch gauge, PSIG. It indicates pressure relative to ambient air, which is what you’re typically concerned with in refrigeration system pressures.

Absolute pressure (PSIA) includes atmospheric pressure in the measurement, giving total pressure rather than just what’s above ambient. Pascals (Pa) are a general pressure unit, but without specifying gauge or absolute. Inches of mercury (Hg) is a traditional unit for pressure that isn’t inherently gauge-focused.