A new method of measuring the oil circulation in the liquid line of refrigeration systems was devised by using the property of oil-absorbing light. The absorption and reference wavelengths were determined with consideration of the absorption spectra of liquid refrigerant and lubricating oil. The oil circulation ratio and transmittance ratio were then investigated for the effect of solution temperature in the cases of R12 (a CFC) and R134a (an HFC) and for the influence of contaminated oil and moisture. This method is accurate and available for non-light-absorbing R12 and light-absorbing R134a, which requires temperature compensation.

KEYWORDS: measuring, refrigeration, refrigerants, light, absorption, lubricants, ratios, R12, R134a, fluorocarbons, temperature, accuracy.