If you are using a recovery machine manufactured before November 15th, 1993, before making a major repair, you must evacuate any low-pressure appliance to _______.

• A. 30 inches of Hg vacuum
• B. 25 inches of Hg vacuum
• C. 20 inches of Hg vacuum
• D. 15 inches of Hg vacuum

Answer: (B)

The correct answer pertains to the requirement for evacuating low-pressure appliances during a major repair when using equipment manufactured before a specific regulatory date. For this scenario, the standard requires achieving a vacuum level of 25 inches of mercury (Hg) before proceeding with repairs.

This specific measurement is in line with industry practices aimed at ensuring all refrigerant vapor and moisture is removed from the appliance. A sufficient vacuum helps to prevent contamination and potential complications during the repair process, as moisture in the system can lead to acid formation and other issues that may damage the components.

Meeting the 25 inches of Hg vacuum threshold is critical for ensuring the integrity of the repair process and for protecting the long-term functionality of the appliance. Adhering to these guidelines is part of the proper protocol established by the EPA to safeguard both the environment and the efficiency of refrigeration systems.