CIRO OP 2 questions with verified
solutions
What was the main disadvantage of hand expansion valves in early refrigeration systems
A. They were big and bulky
B. They always required service because they had many moving parts
C. They did not automatically adjust to changing loads so an operator had to frequently check and adjust
them - correct answer ✔✔C. They did not automatically adjust to changing loads so an operator had to
frequently check and adjust them
What is the advantage of a thermostatic expansion valve
A. They will automatically adjust themselves to match varying load conditions
B. They create fully wetted coil surface with coil capacity equal to a gravity flooded system
C. They can be used on gravity, flooded, recirculated over-feed and DX systems
D. One size fits all evaporators - correct answer ✔✔A. They will automatically adjust themselves to
match varying load conditions
How many forces are involved in operating a thermostatic expansion valve?
A. One - only bulb pressure
B. Two - only the bulb and spring pressure
C. Three - The bulb, spring, and evaporator pressure
D. Four - The bulb, spring, evaporator, and atmospheric pressure - correct answer ✔✔C. Three - The
bulb, spring, and evaporator pressure
Which of the following best describes the term 'flash gas'?
A. The vapor in the last 25% of travel in a DX coil
B. The gas that is discharged out of the compressor
C. The gas that is generated at the orifice of the expansion device
,D. The gas that is traveling down the suction line toward the compressor - correct answer ✔✔C. The gas
that is generated at the orifice of the expansion device
What is the average starting point for setting superheat at the outlet of a DX coil?
A. 5F
B. 10F
C. 25F
D. 1F - correct answer ✔✔B. 10F
Level adjustment of an "LL" type float switch assembly is accomplished by
A. Adjusting the activation screw on the switch mechanism
B. Re-piping or re-attaching the float at a different level
C. Re-calibrating the switch height on the float assembly
D. Entering new level parameters in the float controller - correct answer ✔✔B. Re-piping or re-attaching
the float at a different level
When servicing a DX air unit
A. It is acceptable to use the TXV as an isolation valve as the warm temperature will result in a complete
closing of the valve
B. A separate isolation valve must always be used to isolate the coil
C. The TXV can be used to isolate the coil if the superheat adjustment is turned completely in to the
"manual off" position
D. The TXV can be used to isolate the coil if the superheat adjustment is turned completely out to the
"manual off" position - correct answer ✔✔B. A separate isolation valve must always be used to isolate
the coil
Which of the following is a typical function of a low side vessel?
A. Oil cooling
B. Phase separation
C. Thermosiphon refrigerant storage
D. Subcooling liquid for low side use - correct answer ✔✔B. Phase separation
, If a power element of a TXV lost its charge
A. The evaporator would starve
B. The evaporator would hunt
C. There would be low superheat at the coil outlet
D. The evaporator would flood - correct answer ✔✔A. The evaporator would starve
Hand expansion valves are
A. Seldom used in newer systems
B. Only used to feed gravity flooded evaporators
C. Not used in series with another feed control device
D. Commonly used in series with another feed control device - correct answer ✔✔D. Commonly used in
series with another feed control device
The thermostatic expansion valve is opened by forces coming from
A. Evaporator pressure only
B. Evaporator temperature only
C. Compressor pressure only
D. Sensing bulb pressure - correct answer ✔✔D. Sensing bulb pressure
A hand expansion valve can control the flow of refrigerant into an evaporator better than a typical stop
valve because
A. It is larger than the liquid line pipe size feeding it
B. It has an adjustable orifice designed to control flow
C. It is made of special alloy metal that expands and contracts with temperature change
D. Pointers can be attached to the hand wheel - correct answer ✔✔B. It has an adjustable orifice
designed to control flow
Where may hand expansion valves be found in modern industrial refrigeration systems
A. They are not used
solutions
What was the main disadvantage of hand expansion valves in early refrigeration systems
A. They were big and bulky
B. They always required service because they had many moving parts
C. They did not automatically adjust to changing loads so an operator had to frequently check and adjust
them - correct answer ✔✔C. They did not automatically adjust to changing loads so an operator had to
frequently check and adjust them
What is the advantage of a thermostatic expansion valve
A. They will automatically adjust themselves to match varying load conditions
B. They create fully wetted coil surface with coil capacity equal to a gravity flooded system
C. They can be used on gravity, flooded, recirculated over-feed and DX systems
D. One size fits all evaporators - correct answer ✔✔A. They will automatically adjust themselves to
match varying load conditions
How many forces are involved in operating a thermostatic expansion valve?
A. One - only bulb pressure
B. Two - only the bulb and spring pressure
C. Three - The bulb, spring, and evaporator pressure
D. Four - The bulb, spring, evaporator, and atmospheric pressure - correct answer ✔✔C. Three - The
bulb, spring, and evaporator pressure
Which of the following best describes the term 'flash gas'?
A. The vapor in the last 25% of travel in a DX coil
B. The gas that is discharged out of the compressor
C. The gas that is generated at the orifice of the expansion device
,D. The gas that is traveling down the suction line toward the compressor - correct answer ✔✔C. The gas
that is generated at the orifice of the expansion device
What is the average starting point for setting superheat at the outlet of a DX coil?
A. 5F
B. 10F
C. 25F
D. 1F - correct answer ✔✔B. 10F
Level adjustment of an "LL" type float switch assembly is accomplished by
A. Adjusting the activation screw on the switch mechanism
B. Re-piping or re-attaching the float at a different level
C. Re-calibrating the switch height on the float assembly
D. Entering new level parameters in the float controller - correct answer ✔✔B. Re-piping or re-attaching
the float at a different level
When servicing a DX air unit
A. It is acceptable to use the TXV as an isolation valve as the warm temperature will result in a complete
closing of the valve
B. A separate isolation valve must always be used to isolate the coil
C. The TXV can be used to isolate the coil if the superheat adjustment is turned completely in to the
"manual off" position
D. The TXV can be used to isolate the coil if the superheat adjustment is turned completely out to the
"manual off" position - correct answer ✔✔B. A separate isolation valve must always be used to isolate
the coil
Which of the following is a typical function of a low side vessel?
A. Oil cooling
B. Phase separation
C. Thermosiphon refrigerant storage
D. Subcooling liquid for low side use - correct answer ✔✔B. Phase separation
, If a power element of a TXV lost its charge
A. The evaporator would starve
B. The evaporator would hunt
C. There would be low superheat at the coil outlet
D. The evaporator would flood - correct answer ✔✔A. The evaporator would starve
Hand expansion valves are
A. Seldom used in newer systems
B. Only used to feed gravity flooded evaporators
C. Not used in series with another feed control device
D. Commonly used in series with another feed control device - correct answer ✔✔D. Commonly used in
series with another feed control device
The thermostatic expansion valve is opened by forces coming from
A. Evaporator pressure only
B. Evaporator temperature only
C. Compressor pressure only
D. Sensing bulb pressure - correct answer ✔✔D. Sensing bulb pressure
A hand expansion valve can control the flow of refrigerant into an evaporator better than a typical stop
valve because
A. It is larger than the liquid line pipe size feeding it
B. It has an adjustable orifice designed to control flow
C. It is made of special alloy metal that expands and contracts with temperature change
D. Pointers can be attached to the hand wheel - correct answer ✔✔B. It has an adjustable orifice
designed to control flow
Where may hand expansion valves be found in modern industrial refrigeration systems
A. They are not used
