GCAP INDUSTRIAL AMMONIA REFRIGERATION LATEST
COMPREHENSIVE EXAM QUESTIONS AND ANSWERS
SURE A+
✔✔What would be the % of gas produced if one pound of liquid Ammonia would convert
to gas across the expansion valve with 95° F Condensing temperature and -40° F
evaporating temperature? Flash/Tax gas = {(TD x 1.12) / 561} - ✔✔Approximately 27%
✔✔What are the three feeds? - ✔✔DX or dry expansion, overfeed or recirculated, and
flooded or gravity.
✔✔In a DX or dry expansion evaporator the refrigerant should leave in what condition? -
✔✔Superheated.
✔✔If using a TXV, what style of evaporator are you using? - ✔✔DX
✔✔An increase of heat (superheat) on the "bulb of a TXV" causes what through the
value? - ✔✔Valve to stay open or open more.
✔✔All flooded systems are unique in that they supply SAT liquid refrigerant to the
bottom of the evaporator from what component? - ✔✔Surge drum (LPR)
✔✔Cavitation is good for liquid pump. True or False - ✔✔False
✔✔Semi hermetic pumps have an external motor connected to the Armature with a
mechanical shaft seal. True or False - ✔✔False
✔✔Typically, how much superheat is found on the outlet of an evaporator under normal
load conditions using the overfeed design? - ✔✔0°F
✔✔In hot gas defrost? - ✔✔High-pressure gas from the compressor discharge is piped
through the evaporator.
✔✔What style of systems uses a liquid pump to transfer liquid to evaporators? -
✔✔Overfeed.
✔✔An air evaporator that is tubed with fins, by design what happens to the spacing of
the fins as systems are designed for colder applications? - ✔✔Once design
temperatures are below -32° F, the fins must be spaced further apart due to freezing of
moisture.
, ✔✔In a pump overfeed system, what must shut off in the event of all compressors
shutting down? - ✔✔Liquid feed
✔✔Another reference to the flooded system is? - ✔✔Thermosyphon
✔✔What style of compressor are used in the industrial Ammonia refrigeration system ?
- ✔✔Positive displacement, Reciprocating, and Rotary vane,
✔✔What are the 3 styles of positive displacement compressors used in out industry? -
✔✔Reciprocating, Rotary vane, and Rotary screw
✔✔What is the practical max compression ratio for a rotary vane Compressor? - ✔✔4:1
CR
✔✔What is the practical Max compression ratio of a rotary screw compressor? -
✔✔20:1 CR
✔✔What is the practical max compression ratio for the reciprocating compressor? -
✔✔8:1 CR
✔✔What is one of the most important aspects that an operator must look for before
starting up a compressor? - ✔✔Check oil levels
✔✔Capacity control mechanism of the compressor is actuated by? - ✔✔Suction
pressure
✔✔Typically, reciprocating compressor requiring minimal difference oil pressure of
_______________ above suction pressure? - ✔✔30 -40 PSI
✔✔High discharge temperatures are good for a compressor, creating a black sooty
deposit. True or False - ✔✔False
✔✔How are blades forced outwards in a rotary vane compressor - ✔✔Centrifugal force
✔✔If there is a small percentage of ammonia exhort into the oil, it will cause the oil to
_______________ when the pressure upon the oil is lowered? - ✔✔Foam
✔✔Are oil and liquid ammonia considered to be Misible?( come together to create a
new solution ) - ✔✔No, ammonia is heavier than oil
✔✔No, ammonia is heavier than oil - ✔✔
COMPREHENSIVE EXAM QUESTIONS AND ANSWERS
SURE A+
✔✔What would be the % of gas produced if one pound of liquid Ammonia would convert
to gas across the expansion valve with 95° F Condensing temperature and -40° F
evaporating temperature? Flash/Tax gas = {(TD x 1.12) / 561} - ✔✔Approximately 27%
✔✔What are the three feeds? - ✔✔DX or dry expansion, overfeed or recirculated, and
flooded or gravity.
✔✔In a DX or dry expansion evaporator the refrigerant should leave in what condition? -
✔✔Superheated.
✔✔If using a TXV, what style of evaporator are you using? - ✔✔DX
✔✔An increase of heat (superheat) on the "bulb of a TXV" causes what through the
value? - ✔✔Valve to stay open or open more.
✔✔All flooded systems are unique in that they supply SAT liquid refrigerant to the
bottom of the evaporator from what component? - ✔✔Surge drum (LPR)
✔✔Cavitation is good for liquid pump. True or False - ✔✔False
✔✔Semi hermetic pumps have an external motor connected to the Armature with a
mechanical shaft seal. True or False - ✔✔False
✔✔Typically, how much superheat is found on the outlet of an evaporator under normal
load conditions using the overfeed design? - ✔✔0°F
✔✔In hot gas defrost? - ✔✔High-pressure gas from the compressor discharge is piped
through the evaporator.
✔✔What style of systems uses a liquid pump to transfer liquid to evaporators? -
✔✔Overfeed.
✔✔An air evaporator that is tubed with fins, by design what happens to the spacing of
the fins as systems are designed for colder applications? - ✔✔Once design
temperatures are below -32° F, the fins must be spaced further apart due to freezing of
moisture.
, ✔✔In a pump overfeed system, what must shut off in the event of all compressors
shutting down? - ✔✔Liquid feed
✔✔Another reference to the flooded system is? - ✔✔Thermosyphon
✔✔What style of compressor are used in the industrial Ammonia refrigeration system ?
- ✔✔Positive displacement, Reciprocating, and Rotary vane,
✔✔What are the 3 styles of positive displacement compressors used in out industry? -
✔✔Reciprocating, Rotary vane, and Rotary screw
✔✔What is the practical max compression ratio for a rotary vane Compressor? - ✔✔4:1
CR
✔✔What is the practical Max compression ratio of a rotary screw compressor? -
✔✔20:1 CR
✔✔What is the practical max compression ratio for the reciprocating compressor? -
✔✔8:1 CR
✔✔What is one of the most important aspects that an operator must look for before
starting up a compressor? - ✔✔Check oil levels
✔✔Capacity control mechanism of the compressor is actuated by? - ✔✔Suction
pressure
✔✔Typically, reciprocating compressor requiring minimal difference oil pressure of
_______________ above suction pressure? - ✔✔30 -40 PSI
✔✔High discharge temperatures are good for a compressor, creating a black sooty
deposit. True or False - ✔✔False
✔✔How are blades forced outwards in a rotary vane compressor - ✔✔Centrifugal force
✔✔If there is a small percentage of ammonia exhort into the oil, it will cause the oil to
_______________ when the pressure upon the oil is lowered? - ✔✔Foam
✔✔Are oil and liquid ammonia considered to be Misible?( come together to create a
new solution ) - ✔✔No, ammonia is heavier than oil
✔✔No, ammonia is heavier than oil - ✔✔
