Which of the following is NOT a characteristic of Polyol Ester Oils?

Polyol ester oils are a type of lubricant commonly used with refrigerants, particularly in HVAC applications. One key feature of polyol esters is that they generally have lower viscosity compared to mineral oils, which allows for better fluidity and improved circulation in refrigeration systems.

High viscosity ratings are typically associated with oils that are thicker and may not flow as easily, which can hinder the efficiency of a refrigeration system. In contrast, polyol esters are designed to provide the right balance of viscosity to ensure proper lubrication and heat transfer, making them more effective in modern refrigerant applications.

The characteristics listed in the other choices highlight aspects of polyol ester oils that are relevant to their use. For example, their tendency to draw moisture from the environment makes them susceptible to absorbing water vapor, which can be problematic in refrigeration systems if not managed properly. Additionally, the potential for skin irritation is a safety concern, and the improved heat transfer characteristics over mineral oils underscore their performance benefits in various applications.