RETA CARO EXAM LATEST EXAM 2024 | ALL QUESTIONS AND CORRECT ANSWERS | ALREADY GRADED A+, Exams of Refrigeration and Air Conditioning

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RETA CARO EXAM LATEST EXAM 2024 | ALL QUESTIONS AND CORRECT ANSWERS | ALREADY GRADED A+ | LATEST VERSION (JUST RELEASED) What is indicated when evaporative condensation liquid drain is 90 degrees farenheight and 180Psig? ------CORRECT ANSWER---------------subcooled 5 degrees, or non-condensables Where do non-condensable gasses accumulate? ------CORRECT ANSWER---------------They accumulate in the system's high side What is the greatest threat to maintaining optimal operating pressures in a refrigeration system? ------CORRECT ANSWER---------------Air leaking into the system What is most likely to result from an excessive discharge temp. at outlet of compressor due to non-condensables in refrigeration system? ------ CORRECT ANSWER---------------breakdown of oil, higher compression ratio, non-condensables accumulate breakdown of lubricants and refrigerants What is the temp. for R-22 at 182 Psig? (chart) ------CORRECT ANSWER-- -------------95 degrees What refrigerant is lighter than air at the same temp.? ------CORRECT ANSWER---------------Ammonia Ammonia vapor is flammable at what concentration? ------CORRECT ANSWER---------------16-25% What best describes pipe fitting for ammonia? ------CORRECT ANSWER--- ------------Copper corrodes fast when moisture Which of these may occur when Ammonia is exposed to hot metallic surfaces? ------CORRECT ANSWER---------------Decomposition may occur resulting in release of hydrogen gas. Which statement best describes HCHF's? ------CORRECT ANSWER--------- ------R-22 Which best describes Ammonia at 80 degrees and 177.99Psig? ------ CORRECT ANSWER---------------80 degrees= 138Psig= non-condensables in the system What is the evaporating pressure for R-22 at 20 degrees? ------CORRECT ANSWER---------------43Psig Which best describes a hermetic compressor's advantages? ------ CORRECT ANSWER---------------Breakdown of refrigerants= acids Which of the following is used to measure the quantity of heat energy? ------ CORRECT ANSWER---------------British Thermal Units (BTUS) or calories. When calculating the BTUS that have to be removed to cool a substance, what combination of the following is used? ------CORRECT ANSWER-------- -------pounds of substance, temperature difference, specific heat Latent heat of vaporization ------CORRECT ANSWER---------------is the heat energy required to cause a liquid to become a vapor. Pressure is a measure of ------CORRECT ANSWER---------------the relationship of a force being applied over a given area. The relationship between temperature difference and heat flow is. ------ CORRECT ANSWER---------------The greater the temperature difference the more rapid the heat flows. Specific heat ------CORRECT ANSWER---------------is greater as the substance requires more heat energy to increase temperature. Which is equal to 22 Psig? ------CORRECT ANSWER---------------36.7 Psia What is the Latent Heat of Vaporization?(H2O) ------CORRECT ANSWER-- -------------970 Btu's What product requires the most energy to lower 1 lb. by 1 degree? ------ CORRECT ANSWER---------------water What happens when pressure on a liquid is increased? ------CORRECT ANSWER---------------Boiling point goes up/Saturation temp. goes up What happens when vapor is Superheated? ------CORRECT ANSWER------ ---------Temperature above saturated/it gains sensible heat 0.5x1 degree F What causes heat to move from one object to another when touched? ------ CORRECT ANSWER---------------temperature difference/ conduction What Btu's are needed to convert 10 lbs. of water to 10 lbs. of steam? ------ CORRECT ANSWER---------------10x970= 9,700 Btu's What rate describes the load for 120 tons?(in Btu's/Hr.) ------CORRECT ANSWER---------------Btu/hr= 12,000 so 12,000x120=1,440,000 What is equivalent to 48,000 Btu/hr. in tons? ------CORRECT ANSWER----- ----------48,000 divided by 12,000 = 4 tons What is 100 degrees Celsius in Farenheight? ------CORRECT ANSWER---- -----------212 degrees farenheight figure* Single Stage- Saturation should never occur in? ------CORRECT ANSWER---------------compressor figure* Single Stage- Where is heat absorbed from the product? ------ CORRECT ANSWER---------------Evaporator What is compressed in refrigerant vapors? ------CORRECT ANSWER-------- -------vapors What best describes refrigerants boiling rapidly? ------CORRECT ANSWER---------------saturated/ It's evaporating What is the condensation in a pipe with R-22 at 20Psig & 10 degrees farenheight? ------CORRECT ANSWER----------------5 degrees farenheight, 32.8Psig figure* 2 stage- Which compressor do you start first? ------CORRECT ANSWER---------------High Stage What is monitored to indicate the evaporation temperature? ------ CORRECT ANSWER---------------Suction Pressure What is the least correct thing to do for the oncoming operator? ------ CORRECT ANSWER---------------Assume everything is working okay. Viscosity =? ------CORRECT ANSWER---------------Pour point What is viscosity vs. temperature? ------CORRECT ANSWER---------------Oil may not pour at cooler temp. (warmer=thinner, colder=thicker) When does oxidation occur? ------CORRECT ANSWER---------------Oil molecules break and attach to oxygen, cause higher viscosity means thicker oil When can you mix oil types in a system? ------CORRECT ANSWER---------- -----Never Which is not true on a full internal force feed system on a recip. compressor? ------CORRECT ANSWER---------------They use oil to lower the compressor discharge temp. significantly (the wrist pins are lubricated by splash) How is net oil pressure determined in a recip. system? ------CORRECT ANSWER---------------Suction pressure minus oil pressure (guage readings) Which is best to reduce danger when draining oil? ------CORRECT ANSWER---------------Wear PPE (respirator and clothing) Which is most important when draining oil? ------CORRECT ANSWER------- --------Inform others Which statement best describes safe operating procedures during oil drain? ------CORRECT ANSWER---------------Self closing ball valve Which danger is greatest when draining oil from ammonia system? ------ CORRECT ANSWER---------------oil is under pressure (collects at drain point in an active system, may be under pressure How many step in oil separator? ------CORRECT ANSWER---------------4/3 How much longer do synthetic oils last? ------CORRECT ANSWER----------- ----3 to 5 times longer How do you drain oil from a screw compressor? ------CORRECT ANSWER- --------------S.O.P. standard operating procedure What does a master oil scrubber do? ------CORRECT ANSWER--------------- Condense oil vapor What best describes Brine at low viscosity? ------CORRECT ANSWER------- --------Less HP to move- thinner the oil easier to pump Gravity coils rely..? ------CORRECT ANSWER---------------On Natural Convection What statement best describes forced draft units? ------CORRECT ANSWER---------------Uneven air flow What statement most accurately describes product(blast) freezers? ------ CORRECT ANSWER---------------Greater air velocity across the product surface speeds up freezing What is common to all secondary coolants? ------CORRECT ANSWER------ ---------They don't evaporate as they absorb heat Which of these secondary coolants is safe to handle but most used at operating temp. above 10 degrees? ------CORRECT ANSWER--------------- Sodium Chloride Which of these is likely to be caused by oil in an evaporator ? ------ CORRECT ANSWER---------------Interference with heat transfer process. Which of these service and maintenance steps on cooling units is most likely to receive specialized equipment ? ------CORRECT ANSWER----------- ----Inspecting bearings and belts. Which statement most accurately describes online purging? ------ CORRECT ANSWER---------------Each condenser drain in a system must be drained one at a time Which of these could the high-side pressure be reduced with proper purging of a condenser unit with liquid ammonia at 90 degrees & high-side pressure at 200Psig? ------CORRECT ANSWER---------------non- condensibles, reduced to 166Psig What is the least responsibility of a safety committee? ------CORRECT ANSWER---------------Insurance rates Which statement most accurately describes the greatest hazard on the job for a refrigeration operator? ------CORRECT ANSWER---------------PPE is of limited help when opening and closing valves on most refrigeration equipment Which of these is Least likely to occur if a pipe or vessel is isolated when it is 100% full of liquid refrigerant? ------CORRECT ANSWER--------------- Liquid refrigerant will be equalized or vented automatically as pressure rises inside the unit Why is it recommended that high pressure receivers allow a level at or below 80% liquid? ------CORRECT ANSWER---------------Liquid anhydrous ammonia at -65 degrees will expand 20% when warmed to 125 degrees What is the safe storage capacity of a HPR that could hold 1000 pounds of liquid ammonia at 90 degrees when it is topped off? ------CORRECT ANSWER---------------800 lbs. of ammonia Which of the following valves performs the function of protecting pressure vessels from over pressurization? ------CORRECT ANSWER--------------- Relief valve What is removed from a refrigeration system during purging? ------ CORRECT ANSWER---------------Air (non-condensibles) Why should non-condensible gasses be purged from a refrigeration system? ------CORRECT ANSWER---------------They do not condense at the same temp./pressure as refrigerant inside the system Which statement most accurately describes safety hazards in an ammonia system? ------CORRECT ANSWER---------------Ammonia escaping from a valve stem can cause permanent injury Which statement most accurately describes safety hazards for systems that use synthetic refrigerants? ------CORRECT ANSWER---------------Synthetic refrigerant leaks can smother a person by displacing oxygen Which of these is not among safety tips recommended when working on electricity? ------CORRECT ANSWER---------------Replace all electrical cords at least annually Which of these is most common in fatal electrical accidents? ------ CORRECT ANSWER---------------120 volts Which of these is most likely to reduce electrical hazard for hand tools on the job? ------CORRECT ANSWER---------------Use double insulated tools to reduce the risk of shock What does a safety data sheet (SDS) provide? ------CORRECT ANSWER-- -------------Information about chemical hazards Which statement most accurately describes proper use of fire extinguishers? ------CORRECT ANSWER---------------Foam-type extinguishers are effective in putting out an oil fire Which statement most accurately describes proper first aid for exposure to ammonia? ------CORRECT ANSWER---------------Flush the area that was exposed to ammonia thoroughly with water while waiting for emergency help to arrive. Which statement most accurately describes proper handling or use of fire extinguisher? ------CORRECT ANSWER---------------All employees must be trained to use every type of fire extinguisher Which statement accurately describes chemicals in the work place? ------ CORRECT ANSWER---------------The product manufacturer prepares the SDS to inform users of a chemical product about it's hazards and how to respond to chemical exposure OSHA regulations require persons wearing respiratory protective equipment. ------CORRECT ANSWER---------------a medical evaluation to confirm fitness to wear PPE Which refrigerant has the highest mass flow requirement at the same evaporator and condensing temperature? ------CORRECT ANSWER--------- ------CFC-12 which refrigerant is the first to be phased out by Montreal Protocol ------ CORRECT ANSWER---------------CFC-12 As the ratio between the evaporator and condensing pressure increases --- ---CORRECT ANSWER---------------the theoretical discharge temperature increases Under the Montreal Protocol ------CORRECT ANSWER---------------as long as a technician does not perform work on the refrigerant containing portions of a system they do not need to be certified Refrigerant leaks are detected using ------CORRECT ANSWER--------------- Either a sulfur stick on ammonia or electronic leak detector for CFCs or HCFCs the primary reason for concern about CFC-12 concentration in an engine room is ------CORRECT ANSWER---------------oxygen deprivation the published lower explosive limit for ammonia is ------CORRECT ANSWER---------------16% under normal conditions an ammonia vessel should only be filled to what percentage ------CORRECT ANSWER---------------80% which refrigerant can be detected by its odor even in low concentrations ---- --CORRECT ANSWER---------------R-717 Which refrigerant would have the lowest condensing pressure at 95 Degrees F ------CORRECT ANSWER---------------CFC-11 A cartridge type gas mask may legally be used for personal protection when ------CORRECT ANSWER---------------the type of the hazard is known and the concentration is known a vapor can NOT be ------CORRECT ANSWER---------------subcooled what kind of measure is a to of refrigeration ------CORRECT ANSWER------- --------a rate of heat transfer in BTUs per Unit of time which two forms of heat transfer is most common in refrigeration ------ CORRECT ANSWER---------------conduction and convecton the condition of a boiling liquid is what ------CORRECT ANSWER-------------- -saturated What kind of measurement is a ton of refrigeration ------CORRECT ANSWER---------------A rate of heat transfer in BTUs per unit of time Which is greater 10psia or 10psig ------CORRECT ANSWER--------------- 10psig is greater than 10paia The latent heat of condensation of a substance is the same as what ------ CORRECT ANSWER---------------The latent heat of evaporation of the substance Superheat is found in an air conditioning system in the: ------CORRECT ANSWER---------------Compressor suction line and it's discharge line Subcooled refrigerant can only be what ------CORRECT ANSWER------------ ---Liquid Superheated refrigerant can only be ? ------CORRECT ANSWER-------------- -Vapor Saturated refrigerant can be what? ------CORRECT ANSWER---------------A liquid, vapor or a combination of the two