The temperature at which a refrigerant boils or condenses at a given pressure.
At saturation, liquid and vapour exist together and the refrigerant's temperature is fixed by its pressure. Raise the pressure and the saturation temperature rises; lower it and it falls. A pressure-temperature chart or a digital manifold converts one into the other for each refrigerant.
Inside a working evaporator and condenser most of the refrigerant is at saturation, which is why gauge pressure is really a temperature reading. Superheat and subcooling are both measured from it.
Exam work areas
B · Tools, piping and refrigerant handling E · Commissioning and start-up F · Maintenance, service and troubleshooting