RETA CARO STUDY GUIDE JH EXAM NEWEST 2024 ACTUAL EXAM COMPLETE 300 QUESTIONS AND CORRECT DETAILED ANSWERS (VERIFIED ANSWERS)

What best describes pipe fitting for ammonia? - ANSWERS,Copper corrodes fast when moisture Which of these may occur when Ammonia is exposed to hot metallic surfaces? - ANSWERS,Decomposition may occur resulting in release of hydrogen gas. Which statement best describes HCHF's? - ANSWERS,R-22 Which best describes Ammonia at 80 degrees and 177.99Psig? - ANSWERS,80 degrees= 138Psig= non-condensables in the system What is the evaporating pressure for R-22 at 20 degrees? - ANSWERS,43Psig Which best describes a hermetic compressor's advantages? - ANSWERS,Breakdown of refrigerants= acids What determines the capacity of a Recip. compressor? - ANSWERS,CFM= cubic feet per minute What is the practical limit of a recip. compressor? - ANSWERS,8:1 Which compressor would work best at -10 degrees evap. and 95 degrees condensing? -10 degrees= 23.66PsiA 95 degrees=195.8PsiA - ANSWERS,195.8 divided by 23.66= 8.27:1 What best describes the operations of a rotary compressor? - ANSWERS,Positive displacement compressor What is the purpose of a capacity control mechanism in a compressor? - ANSWERS,to adjust the load figure* 2 stage- Which compressor do you start first? - ANSWERS,High Stage What is monitored to indicate the evaporation temperature? - ANSWERS,Suction Pressure What is the least correct thing to do for the oncoming operator? - ANSWERS,Assume everything is working okay. What is the purpose of a crankcase heater? - ANSWERS,Keep oil warm What danger should you look for when starting a compressor? - ANSWERS,Rapid pressure drop What causes hydraulic pounding in a recip. compressor? - ANSWERS,Liquid What do you do if the recip. compressor is pounding? - ANSWERS,Close suction valve/ turn it off What will cause vapor lock? - ANSWERS,Foam, vapor, cavitation What follows a screw compressor anti-recycle step? - ANSWERS,Start oil pump/ need oil pressure to work What happens when ammonia vapor operates at 140 degrees and suddenly drops to 100 degrees? - ANSWERS,Slugging Why is slugging dangerous in a compressor? - ANSWERS,Damage compressor(only compress vapor), mechanical damage to compressor and refrigerant loss What is most likely to cause pounding in a recip. compressor? - ANSWERS,No oil in heater/ no crankcase heater What cools a rotary vane compressor? - ANSWERS,Oil, they are cooled with an oil jacket? What is essential before starting a screw compressor? - ANSWERS,Oil separator & standby lever? What statement best describes record keeping? - ANSWERS,Regular, all, internal @ shafts Too much compression jogging will? - ANSWERS,Overheat, burn windings (compressor is only meant to compress vapor) Why is oil needed in a compressor? - ANSWERS,All rotating machinery needs lubrication What best describes oil separators in devices? - ANSWERS,They allow some oil through (oil separators are not 100% effective?) Viscosity =? - ANSWERS,Pour point What is viscosity vs. temperature? - ANSWERS,Oil may not pour at cooler temp. (warmer=thinner, colder=thicker) When does oxidation occur? - ANSWERS,Oil molecules break and attach to oxygen, cause higher viscosity means thicker oil When can you mix oil types in a system? - ANSWERS,Never Which is not true on a full internal force feed system on a recip. compressor? - ANSWERS,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? - ANSWERS,Suction pressure minus oil pressure (guage readings) Which is best to reduce danger when draining oil? - ANSWERS,Wear PPE (respirator and clothing) Which is most important when draining oil? - ANSWERS,Inform others Which statement best describes safe operating procedures during oil drain? - ANSWERS,Self closing ball valve Which danger is greatest when draining oil from ammonia system? - ANSWERS,oil is under pressure (collects at drain point in an active system, may be under pressure