RP-887 -- Develop Corrosion Data With Metals of Construction and New Refrigerant/Lubricants at Various Moisture and Organic Acid Levels ✓ Most Recent

Environmentally mandated changes in refrigerant system working fluids have created significant changes in the interactions between these fluids and system construction materials - metals, polymers, elastomers, and process fluids. The investigation exposed five metals and a joined metal couple, commonly used in refrigerant system construction, to refrigerant R-134a and an additive free branched acid polyolester lubricant. Exposures were made in sealed glass tubes at three elevated temperatures. To further accelerate the effects that might occur in actual systems, the exposures included two higher-than-normal moisture levels and two organic acid concentrations. Anion analyses by ion chromatography were conducted on lubricants at four intervals during the aging exposures to show the rate of concentration changes of the added, and resulting, acids. Gravimetric analysis of the metals were conducted at these same intervals to show the rate of metal depletion. Scanning electron microscope analyses were made to characterize the corrosion of each metal. Infrared analyses were conducted on solid materials that formed during the exposures, if quantities were sufficient, and gas chromatographic analyses were conducted on the tube vapor phase to verify refrigerant stability during aging.