HVAC: EPA 608 Certification Study Guide with Verified Solutions 2024

HVAC: EPA 608 Certification Study Guide with Verified Solutions 2024 Are there drop-in replacements for R-12 systems? Why or why not? - Answer -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? - Answer -Ester based oils and they do not mix with other oils What type of lubricant is used with HCFCs? - Answer -Alkylbenzene lubricant What is difference b/w ternary blend a azeotropic blend? - Answer -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? - Answer -It absorbs (takes on) moisture What is temperature glide and what type of blend won't have it? - Answer -Temp. blend is the difference between the dew point and the bubble point Dew Point - Answer -Occurs when saturation temp in evaporator causes refrigerant to change from liquid to vapor Bubble Point - Answer -Occurs when saturation temp in condenser changes refrigerant from vapor to liquid Will the gases in a ternary blend leak at the same rate? Why or why not? - Answer -No because different refrigerants in blend have different vapor pressures, causing them to leak at uneven rates Refrigeration Process - Answer -transfer of heat from one place to another Evaporator - Answer -Absorbs heat into system from space to be cooled. Absorption of heat causes refrigerant to boil. Upon leaving, refrigerant changed to low pressure, low temperature vapor Compressor - Answer -Takes low pressure, low temp vapor and changes it to a high-temp, high-pressure, superheated vapor and delivers it to the condenser Condenser - Answer -Rejects heat from system and changes refrigerant from high-temp, high-pressure vapor into high-pressure, high-temp liquid Metering Device - Answer -reduces pressure of refrigerant and changes the high-pressure, high-temp liquid into low pressure, low temp liquid.Compound Gauge - Answer -Typically blue and measures low pressure (psig) and vacuum (inHg). High Pressure Gauge - Answer -Red and measures high side (discharge) pressure. 0 to 500 ps