According to EPA's regulations, what method can be used to pressurize an R11 or R123 system for non-major repairs?

The correct method for pressurizing an R11 or R123 system for non-major repairs, according to EPA regulations, involves warming the refrigerant. This approach is beneficial because it uses the properties of the refrigerant within the system while ensuring the integrity and safety of the system. Warming the refrigerant increases its pressure, allowing for safe leak detection and ensuring a controlled environment during maintenance activities.

Using nitrogen or other gases such as compressed air or carbon dioxide is not recommended in this scenario. Nitrogen can safely be used to pressurize a system, mainly when testing for leaks, but it is typically not the standard method for working directly with existing refrigerant in an R11 or R123 system during non-major repairs. Compressed air can introduce moisture and contaminants into the system, which can lead to corrosion and damage. Similarly, carbon dioxide can result in high pressure that may be unsafe for the system designed for specific refrigerants like R11 or R123. Thus, warming the refrigerant maintains system compatibility and avoids the risks associated with introducing foreign substances.