Saturation point on a refrigerant is the same as a boiling point or a condensing point. In other words, the saturation point is the temperature at which the refrigerant changes states rather it be from liquid to gas or from gas to liquid. Each refrigerant has a different boiling points or saturation points and even when you are dealing with the same refrigerant the saturation point can change depending on the pressure that is measured.
For those of you who do not know boiling points on gases or liquids can change depending on the pressure on the chemical. So, while we all know water freezes at thirty-two degrees Fahrenheit what you may not know is that this freeze only occurs when water is at one atmospheric pressure. (Also known as Sea Level.) If this pressure changes then the actual freezing point or boiling point of water will change as well.
In the air conditioning world everything is controlled by temperatures and pressure. So, depending on the pressure of the refrigerant you are dealing with the boiling point or saturation point will change. In order to determine this saturation temperatures technicians will measure the pressure and then convert the pressure reading over to the corresponding temperature. This can either be done with refrigerant specific gauges or with a portable refrigerant pressure temperature chart.