Which property is desirable for ammonia refrigerant oil?

The desirable property for ammonia refrigerant oil is being free of water. Water contamination in ammonia refrigerant oil can lead to several issues. Primarily, the presence of water can cause the formation of ice in low-temperature applications, which may clog filters and disrupt the normal functioning of the refrigeration system. Additionally, water can react with ammonia to form ammonium hydroxide, which can contribute to corrosion and degrade both the oil and the refrigeration system components.

While high paraffin content might be preferred in certain contexts, it is not universally desirable for ammonia refrigerant oil, as it can affect the oil's miscibility and flow characteristics, potentially leading to complications in operation. A very low flash point is hazardous, as it increases the risk of fire and safety concerns. Therefore, ensuring ammonia refrigerant oil is free of water is critical for maintaining optimal performance and longevity of the refrigeration system.