EVALUATION OF FILM-FORMING CAPABILITY OF REFRIGERATION LUBRICANTS IN PRESSURIZED REFRIGERANT ATMOSPHERE

In order to investigate the effect of refrigerant on the film-forming capability of refrigeration lubricant, we have developed an apparatus to measure oil film thickness under pressurized refrigerant atmosphere . As a result of comparison among several types of lubricants, mineral oils (particularly naphthenic mineral oil) which were currently used showed superior ability of film-formation to new synthetic ones, polya lkylene glycol (FAG) or polyol ester (PE), in a vacuum. However, the l evel of superiority reduced as the refrigerant pressure increased, thu s the capability was identical to that of synthetics at a pressure of 0.6 MPa, On the other hand, there was little difference between FAG an d PE at the atmospheric pressure of vacuum to 0.6 MPa. It was estimate d that the pressure-viscosity coefficients of these new refrigeration lubricants were almost identical.