EPA 608 HVAC Certification Study Guide Q&A Verified 100%

EPA 608 HVAC Certification Study Guide Q&A Verified 100% 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 How often should refillable cylinders be hydrostatically tested? - 5 years What are the three ways you can control fill level of refillable cylinder? - Mechanical floats, electronic floats, or weight