R12 -- Lubricants in Refrigerant Systems (I-P)

The primary function of a lubricant is to reduce friction and minimize wear. It achieves this by interposing a film between moving surfaces that reduces direct solid-to-solid contact or lowers the coefficient of friction. Understanding the role of a lubricant requires analysis of the surfaces to be lubricated. Although bearing surfaces and other machined parts may appear and feel smooth, close examination reveals microscopic peaks (asperities) and valleys. Lubricant, in sufficient amounts, creates a layer thicker than the maximum height of the mating asperities, so that moving parts ride on a lubricant cushion. Tests for Boundary and Mixed Lubrication Refrigeration Lubricant Requirements Synthetic Lubricants Mineral Oil Composition and Component Characteristics Lubricant Additives Lubricant Properties Lubricant/Refrigerant Solutions Lubricant Influence on Lubricant Return Lubricant Influence on System Performance Wax Separation (Floc Tests) Solubility of Hydrocarbon Gases Lubricants for Carbon Dioxide Solubility of Water in Lubricants Solubility of Air in Lubricants Foaming and Antifoam Agents Oxidation Resistance Chemical Stability Retrofitting from CFC/HCFC to Other Refrigerants