NATE: Pressure–Temperature Relationship - Saturation Curve Basics — Flashcards

For a given refrigerant, saturation pressure corresponds to a saturation temperature (boiling/condensing point). When refrigerant is a liquid+vapor mixture, its temperature is pinned near saturation for that pressure. This is why PT charts and gauges matter.
Key keywords:
• Saturation temperature (Tsat) = boiling/condensing temperature at a given pressure
• Above Tsat at same pressure = superheated vapor
• Below Tsat at same pressure = subcooled liquid

Worked example (concept):
A low-side gauge shows a suction pressure that corresponds to a Tsat of 40°F (for that refrigerant). If the suction line temperature is 55°F, superheat = 55 − 40 = 15°F.