Which property is critical for ammonia refrigerant oil?

The critical property for ammonia refrigerant oil is that it must be free of water. Water can lead to several issues in refrigeration systems utilizing ammonia. When water is present in the oil, it can react with ammonia, leading to the formation of corrosive compounds and reducing the overall efficiency of the system. Additionally, water in the oil can cause the oil to become emulsified, which adversely affects its lubricating properties and can lead to increased wear and tear on the system components.

Ensuring that the refrigerant oil is free of water helps maintain system integrity, efficiency, and longevity. Proper handling and storage of refrigerants and their associated oils is vital to prevent contamination and to ensure optimal performance of the refrigeration system.