What is the reason oxygen should not be used to pressurize a refrigeration system for leak checking?

Using oxygen to pressurize a refrigeration system for leak checking presents significant safety risks, primarily due to the potential for explosion. Oxygen supports combustion, and when introduced into a closed system that contains combustible materials or oils, it creates the conditions for a highly explosive reaction. If a spark or high heat were to be introduced into the system, the presence of oxygen could lead to a violent explosion, posing serious safety hazards to personnel and equipment.

In addition, while factors like corrosion, fire hazards, and compressor damage are valid concerns when working with different gases, the explosive nature of oxygen in combination with flammable materials is the most critical risk, making it paramount to avoid using oxygen for this purpose. For leak testing, inert gases such as nitrogen are preferred since they do not react with other substances in the system and significantly reduce the risk of fire or explosion. This understanding is crucial for maintaining safe operating procedures in a refrigeration environment.