What is recommended to break the vacuum when dehydrating by the triple evacuation method?

Using dry nitrogen to break the vacuum during the triple evacuation method is recommended because it helps to ensure that the system remains moisture-free as the vacuum is being broken. The triple evacuation method is a process used to remove moisture from a refrigeration system, and introducing nitrogen at this stage prevents the introduction of water vapor or other contaminants that could compromise the integrity and efficiency of the system.

Dry nitrogen is inert and non-reactive, making it an ideal choice for this purpose. It does not contribute to the moisture level in the system and assists in properly pressurizing the system after the vacuum has been established and maintained, effectively protecting the equipment and enhancing its longevity and overall performance.

Other options would introduce variables that could negatively affect the system. For example, water vapor could reintroduce moisture that needs to be removed, air contains oxygen and moisture that can corrode metal parts and degrade refrigerants, and carbon dioxide could lead to potential reactions or scenarios that may hinder system functionality. Therefore, dry nitrogen is the safest and most effective choice for breaking the vacuum.