age 1 of 47
Z-51 TEST 2025 LATEST 400 REAL EXAM QUESTIONS
AND CORRECT ANSWERS/ Z-51 REFRIGERATION TEST
EXAM
What is a superheated vapor? ......ANSWER........completely dry
vapor
In electrical circuits the conductor is always what color?
......ANSWER........Green or Bare
Unloaders are used for what? ......ANSWER........To increase
capacity
Oil foaming in a crankcase is caused by what?
......ANSWER........A sudden drop in crankcase pressure
,age 2 of 47
How would you test for acid in the refrigerant?
......ANSWER........Spraying liquid refrigerant from a condenser
or receiver on to bond paper
What is the function of a cylinder bypass? ......ANSWER........To
allow operation at different capacities
The chilled water supply to the building is 55F. If the chiller is
being used for human comfort, should you be concerned about
this, and why? ......ANSWER........Yes. this temperature is too high
for human comfort purpose
The packing gland of a centrifugal pump serves to:
......ANSWER........The drip part of the packing gland gives
evidence that there is water in the pump
,age 3 of 47
Capacity control of a reciprocating hermetic compressor is
typically achieved through ......ANSWER........Operation of the
hot gas bypass valve
The most important reason to sub-cool the refrigerant in the
condenser is to ensure that: ......ANSWER........A pure liquid
refrigerant will enter the metering device
A refrigeration engineer is logging reading from a reciprocating
system. compressor discharge temperature have dropped
significantly and the suction line pressure is high. which of the
following that may be causing this set of condition.
......ANSWER........An expansion valve that is open to wide
A low side float valve is used to maintain: ......ANSWER........The
level of the refrigerant in the evaporator
, age 4 of 47
Regarding fire safety, which ASHRAE refrigerant safety
classification indicates no flammability and lower toxicity?
......ANSWER........A1
All liquid has been recovered from a system to be overhauled,
the system ......ANSWER........Should not be opened until all vapor
has been recovered
When a refrigerant engineer uses a portable compressor
recovery unit to remove vapor refrigerant from a refrigeration
system the removal rate of the refrigerant will gradually slow
down because ......ANSWER........The vapor density is decreasing
You are the engineer running a 2000-ton (steam-driven turbine)
centrifugal refrigeration system, a refrigeration system supplies
chilled water to a college campus with multiple buildings. During
the course of making your rounds, you check the 9 cell cooling
Z-51 TEST 2025 LATEST 400 REAL EXAM QUESTIONS
AND CORRECT ANSWERS/ Z-51 REFRIGERATION TEST
EXAM
What is a superheated vapor? ......ANSWER........completely dry
vapor
In electrical circuits the conductor is always what color?
......ANSWER........Green or Bare
Unloaders are used for what? ......ANSWER........To increase
capacity
Oil foaming in a crankcase is caused by what?
......ANSWER........A sudden drop in crankcase pressure
,age 2 of 47
How would you test for acid in the refrigerant?
......ANSWER........Spraying liquid refrigerant from a condenser
or receiver on to bond paper
What is the function of a cylinder bypass? ......ANSWER........To
allow operation at different capacities
The chilled water supply to the building is 55F. If the chiller is
being used for human comfort, should you be concerned about
this, and why? ......ANSWER........Yes. this temperature is too high
for human comfort purpose
The packing gland of a centrifugal pump serves to:
......ANSWER........The drip part of the packing gland gives
evidence that there is water in the pump
,age 3 of 47
Capacity control of a reciprocating hermetic compressor is
typically achieved through ......ANSWER........Operation of the
hot gas bypass valve
The most important reason to sub-cool the refrigerant in the
condenser is to ensure that: ......ANSWER........A pure liquid
refrigerant will enter the metering device
A refrigeration engineer is logging reading from a reciprocating
system. compressor discharge temperature have dropped
significantly and the suction line pressure is high. which of the
following that may be causing this set of condition.
......ANSWER........An expansion valve that is open to wide
A low side float valve is used to maintain: ......ANSWER........The
level of the refrigerant in the evaporator
, age 4 of 47
Regarding fire safety, which ASHRAE refrigerant safety
classification indicates no flammability and lower toxicity?
......ANSWER........A1
All liquid has been recovered from a system to be overhauled,
the system ......ANSWER........Should not be opened until all vapor
has been recovered
When a refrigerant engineer uses a portable compressor
recovery unit to remove vapor refrigerant from a refrigeration
system the removal rate of the refrigerant will gradually slow
down because ......ANSWER........The vapor density is decreasing
You are the engineer running a 2000-ton (steam-driven turbine)
centrifugal refrigeration system, a refrigeration system supplies
chilled water to a college campus with multiple buildings. During
the course of making your rounds, you check the 9 cell cooling
