What is the required evacuation level for low-pressure appliances before making a major repair on units manufactured before November 15, 1992?

The required evacuation level for low-pressure appliances before making a major repair on units manufactured before November 15, 1992, is 25 inches of mercury (Hg) vacuum. This standard is based on EPA regulations that outline safe practices for handling refrigerants and ensuring that no harmful vapors are released into the atmosphere during repairs.

Low-pressure appliances often contain significant amounts of refrigerant, and reaching the proper evacuation level is essential to ensure that all refrigerant is removed from the system. Achieving a vacuum of 25 inches of Hg helps to ensure that sufficient lower pressure is reached, allowing for safe repairs without the risk of refrigerant escaping into the environment.

For reference, while other evacuation levels may be relevant for different systems or scenarios, 25 inches of Hg is specifically the threshold set for low-pressure appliances as part of the regulations surrounding the servicing of older refrigeration units.