The term "hygroscopic" refers to a substance that can readily absorb moisture from the air. All the polyol ester lubricants, including SOLEST products, will absorb more water than the mineral oils they are replacing.
High levels of moisture in a refrigeration system can adversely affect system performance. However, by following good working practices and minimizing the time a lubricant is exposed to the air, the lubricant will maintain low levels of moisture.
Polyol Ester Lubricants
