What must recovery equipment be capable of on a system with an operating compressor?

The requirement for recovery equipment when handling refrigerants from a system with an operating compressor is based on the ability to effectively recover refrigerant and minimize it being released into the atmosphere. The correct answer states that recovery equipment must be capable of recovering 90% of the refrigerant or achieving a vacuum of 4 inches of mercury.

This standard ensures that a significant amount of refrigerant is removed from the system, preventing environmental harm and complying with regulatory standards designed to protect the ozone layer. The capability to achieve 4 inches of vacuum is also critical because it indicates the equipment's efficiency in removing remaining refrigerant gas from the system after the majority has been recovered.

While the other answers propose different percentages or vacuum levels, they do not meet the established standards for safe and efficient recovery of refrigerants in systems with operating compressors. For instance, recovering only 80% or less would not be sufficient to meet environmental regulations, and achieving a vacuum of 0 inches would indicate that the refrigerant is not completely removed, which is not permissible. Thus, the choice that specifies 90% recovery or 4 inches of vacuum aligns with the necessary performance criteria for recovery equipment.