HVAC: EPA 608 Certification Study Guide questions with correct answers

Are there drop-in replacements for R-12 systems? Why or why not? ans No because the new refrigerants are incompatible with the oils and lubricants used in R-12 systems. What type of oil is used in R-134a and what oils will it mix with? ans Ester based oils and they do not mix with other oils What type of lubricant is used with HCFCs? ans Alkylbenzene lubricant What is difference b/w ternary blend a azeotropic blend? ans Ternary blends are three-part mixtures whereas azeotropic blends are blends of two or more compounds that act like a single compound. What is the trait of a hygroscopic lubricant? ans It absorbs (takes on) moisture What is temperature glide and what type of blend won't have it? ans Temp. blend is the difference between the dew point and the bubble point Dew Point ans Occurs when saturation temp in evaporator causes refrigerant to change from liquid to vapor Bubble Point ans Occurs when saturation temp in condenser changes refrigerant from vapor to liquid