What absolute vacuum level should be achieved before charging a refrigeration system with refrigerant?

Achieving the correct absolute vacuum level before charging a refrigeration system with refrigerant is crucial for the efficiency and longevity of the system. The appropriate vacuum level required is typically less than 2000 microns (or 2 microns of mercury). This indicates that the system needs to be sufficiently free of moisture and contaminants, which can cause issues such as corrosion, freezing, or reduced efficiency.

A vacuum reading of less than 2000 microns signifies that the majority of air and moisture have been evacuated from the system. This is critical because even small amounts of moisture can lead to problems like the formation of acids, which can damage the compressor and other components of the refrigeration system.

In this context, the choice stating a reading of less than 2000 microns is ideal as it meets the industry-standard guidelines for vacuum levels before recharging a system. This ensures the integrity of the refrigeration cycle, preventing potential operational failures after the system is charged with refrigerant.