It is the act of producing a vacuum, with the elimination of the unconstensible vapors inside the refrigeration system.
Dehydration is the act of dehydrating, that is, removing moisture from inside the cooling system.
The evacuation and dehydration task is one of the most important tasks that the refrigeration mechanic needs to perform in order to recover a refrigerator unit. Experience shows that the refrigeration unit does not operate normally if it contains moisture or incondensable gases. Moisture causes clogging in the refrigeration circuit due to “freezing” at the outlet of the expansion device. Uncondensable gases promote increased pressure in the condenser, making condensation of the refrigerant difficult. Oxygen, in particular, can oxidize the oil where the temperature is highest. It is therefore necessary to evacuate and dehydrate the refrigeration system simultaneously, before charging the refrigerant. Evacuation and dehydration are carried out by means of vacuum pumps, always following the manufacturer's guidance at the appropriate “vacuum” level.
