HVAC: EPA 608 CERTIFICATION STUDY GUIDE|UPDATED&VERIFIED|100% SOLVED|GUARANTEED SUCCESS

Are there drop-in replacements for R-12 systems? Why or why not? 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? Ester based oils and they do not mix with other oils What type of lubricant is used with HCFCs? Alkylbenzene lubricant What is difference b/w ternary blend a azeotropic blend? 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? It absorbs (takes on) moisture What is temperature glide and what type of blend won't have it? Temp. blend is the difference between the dew point and the bubble point Dew Point Occurs when saturation temp in evaporator causes refrigerant to change from liquid to vapor Bubble Point 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? No because different refrigerants in blend have different vapor pressures, causing them to leak at uneven rates Refrigeration Process transfer of heat from one place to another Evaporator 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 Takes low pressure, low temp vapor and changes it to a high-temp, high-pressure, superheated vapor and delivers it to the condenser Condenser Rejects heat from system and changes refrigerant from high-temp, high-pressure vapor into high-pressure, high-temp liquid Metering Device reduces pressure of refrigerant and changes the high-pressure, high-temp liquid into low pressure, low temp liquid. Compound Gauge Typically blue and measures low pressure (psig) and vacuum (inHg). High Pressure Gauge Red and measures high side (discharge) pressure. 0 to 500 psi What does a compressor compress? Vapor Why will refrigerant migrate to the crankcase in a compressor? Because of the vapor pressure difference between refrigerant and oil What color is the high pressure gauge? Red What color is the low pressure gauge? Blue What needs to happen if oil has been contaminated by burnout? Triple evacuate system, install permanent filter-drier, conduct deep vacuum before recharging What are three Rs of refrigeration? Recover, recycle, reclaim Recover to remove any refrigerant in any condition from system and store in external container without necessarily testing or processing in any way Recycle To clean refrigerant for immediate reuse by separating oil from refrigerant and removing moisture and acidity from refrigerant by use of products like filter driers Reclaim To process refrigerant to level of new product specifications as determines by chemical analysis What standards must refrigerant recovery equipment meet and what components must all Type I and Type II refrigerant systems have? EPA-approved equipment testing organization. Service aperture or process stub System-Dependent Devices Capture refrigerant with assistance of compressor and/or pressure of refrigerant in appliances from which refrigerant is being recovered Self-contained Devices Have independent means to draw refrigerant out of appliances What is nitrogen and a filter-drier used for after recovery? Use nitrogen to flush debris out of system after recovering refrigerant. Filter-drier should be installed to trap any debris that may cause damage to new compressor What must be done before starting an evacuation? Recover all refrigerant and attain the mandated vacuum level ASHRAE Standard 15-1994 Requires refrigerant sensor that will sound alarm and automatically start ventilation system in occupied equipment rooms where refrigerant from leak will concentrate