3909 -- Inorganic Fluoride Uptake as a Measure of Relative Compatibility of Molecular Sieve Desiccants with Fluorocarbon Refrigerants PDF

The fluoride content of molecular sieve desiccants offer exposure to R32 in compatibility tests indicates the extent of the reaction of refrigerant with desiccant. The objective is to determine this fluoride content in a way that reports fluorine that has reacted with the desiccant, not fluorine that is present as adsorbed refrigerant. A conditioning procedure is described to remove adsorbed refrigerant by displacement with water vapour. The efficacy of this procedure is substantiated by 19F NMR spectroscopy. The conditioned desiccant undergoes pyrohydrolysis at a high temperature (975degC [1787degF]) to remove reacted fluorine as HF. Fluoride is determined in the resulting condensate using an ion-selective electrode. The ability of this technique to report accurate fluoride values is confirmed with standard reference materials.

KEYWORDS: year 1995, fluorides, fluorine, content, desiccants, compatibility, testing, fluorocarbons, refrigerants, R32, spectrometers, water vapour