2
Refrigeration Test 4 with accurate detailed answers || || || || || ||
17-1) What happens to the refrigerant as it passes through the metering device? - ✔✔The
|| || || || || || || || || || || || || || ||
refrigerant drops in pressure and temperature as it passes through the metering device. A
|| || || || || || || || || || || || || ||
small portion of the refrigerant flashes to a vapor, cooling the remaining liquid.
|| || || || || || || || || || || ||
17-2) Explain the difference between a fixed metering device and a modulating metering
|| || || || || || || || || || || || ||
device. - ✔✔A fixed metering device cannot change to respond to system changes, a
|| || || || || || || || || || || || || ||
modulating metering device can. || || ||
17-3) What are the two types of fixed metering devices? - ✔✔Capillary tubes and orifices
|| || || || || || || || || || || || || ||
17-4) List the advantages of the capillary tube. - ✔✔The cap tube is simple, inexpensive,
|| || || || || || || || || || || || || || ||
and cap tube systems can be used with low starting torque compressors
|| || || || || || || || || || ||
17-5) Explain the basic operation of the automatic expansion valve - ✔✔The automatic
|| || || || || || || || || || || || ||
expansion valve is a refrigerant pressure regulator. It is controlled by a diaphragm which
|| || || || || || || || || || || || || ||
balances the evaporator pressure against an adjustable spring pressure.
|| || || || || || || ||
17-6) Why is the automatic expansion valve not suited for systems with varying loads? -
|| || || || || || || || || || || || || || ||
✔✔The response of the automatic expansion valve to load changes causes it to feed more
|| || || || || || || || || || || || || || ||
refrigerant when the load decreases and less refrigerant when the load increases.
|| || || || || || || || || || ||
17-7) Which way would the adjustment on top of an automatic expansion valve be turned
|| || || || || || || || || || || || || || ||
to increase the evaporator pressure? - ✔✔Clockwise
|| || || || || ||
17-8) What does a thermostatic expansion valve try to regulate and keep stable? -
|| || || || || || || || || || || || || ||
✔✔Superheat
,2
17-9) What is the difference between internally and externally equalized thermostatic
|| || || || || || || || || || ||
expansion valves? - ✔✔Internally equalized valves obtain the evaporator pressure through a
|| || || || || || || || || || || ||
passageway inside the valve. Externally equalized valves obtain evaporator pressure through
|| || || || || || || || || || ||
a separate line which runs from the valve to the suction line.
|| || || || || || || || || || ||
17-10) How does a TEV with MOP work? - ✔✔MOP valves have a gas charge. Gas charged
|| || || || || || || || || || || || || || || || ||
bulbs have only a small amount of liquid in the bulb. When the valves reaches the MOP,
|| || || || || || || || || || || || || || || || ||
maximum operating pressure, there is no more liquid in the bulb. This greatly limits the
|| || || || || || || || || || || || || || ||
bulb opening pressure.
|| ||
17-11) What is the difference between a traditional TEV and a balanced port TEV? - ✔✔A
|| || || || || || || || || || || || || || || ||
traditional TEV is affected by the pressure drop across the valve. Increased pressure
|| || || || || || || || || || || || ||
difference tends to open the valve more. A balanced port valve is designed to counteract
|| || || || || || || || || || || || || || ||
the effect of pressure difference across the valve, so the valve can retain good control at a
|| || || || || || || || || || || || || || || || ||
much wider range of operating conditions.
|| || || || ||
17-12) What is the difference between a traditional liquid charged TEV bulb and a liquid
|| || || || || || || || || || || || || || ||
cross-charged TEV bulb? - ✔✔A traditional charge uses the same refrigerant as is in the
|| || || || || || || || || || || || || || ||
system. A cross charged bulb contains a different refrigerant than the system, so the
|| || || || || || || || || || || || || ||
pressure response of the bulb crosses the pressure response of the system at some point.
|| || || || || || || || || || || || || ||
17-13) What is the purpose of a liquid distributor? - ✔✔A liquid distributor is used to
|| || || || || || || || || || || || || || || ||
evenly distribute the mixture of liquid and vapor refrigerant leaving
|| || || || || || || || ||
17-14) Which way would the adjusting stem on an expansion valve be turned to increase
|| || || || || || || || || || || || || || ||
the superheat? - ✔✔Clockwise
|| || ||
17-15) Which way would the adjusting stem on an expansion valve be turned to decrease
|| || || || || || || || || || || || || || ||
superheat? - ✔✔Counter clockwise || || ||
,2
17-16) What types of problems could cause a TEV system to operate at too high a
|| || || || || || || || || || || || || || || ||
superheat? - ✔✔System undercharge, liquid line refrigerant restriction, dead TEV power
|| || || || || || || || || || ||
element, TEV plugged with debris from brazing
|| || || || || ||
17-17) Why must technicians be careful when brazing lines to evaporator coils which have
|| || || || || || || || || || || || || ||
thermostatic expansion valves? - ✔✔The heat from brazing the lines can conduct through
|| || || || || || || || || || || || ||
the lines to the TEV bulb and destroy the bulb by building up very high pressure in the
|| || || || || || || || || || || || || || || || || ||
power head. ||
17-18) How can a capillary tube that is restricted with debris be differentiated from a
|| || || || || || || || || || || || || || ||
capillary tube that is restricted with ice? - ✔✔A capillary tube that is plugged with debris
|| || || || || || || || || || || || || || || ||
will immediately pull into a very low suction pressure or vacuum. Ice normally only forms
|| || || || || || || || || || || || || || ||
after the system has operated some and the evaporator starts getting cold.
|| || || || || || || || || || ||
17-19) What is a bi-flow expansion valve? - ✔✔A bi-flow expansion valve is designed to
|| || || || || || || || || || || || || || ||
allow refrigerant flow in both directions. Some bi-flow valves meter the refrigerant in both
|| || || || || || || || || || || || || ||
directions while others allow unrestricted flow in the reverse direction.
|| || || || || || || || ||
17-20) What system operating characteristics would you expect from a system which has a
|| || || || || || || || || || || || || ||
TEV with a dead power element? - ✔✔The suction pressure would be very low, possibly in
|| || || || || || || || || || || || || || || ||
a vacuum. The superheat and subcooling would both be high. The system would not cool.
|| || || || || || || || || || || || || ||
17-21) What system operating characteristics would you expect from a system which has a
|| || || || || || || || || || || || || ||
TEV with a loose sensing bulb? - ✔✔The suction pressure would be high. The superheat
|| || || || || || || || || || || || || || ||
and subcooling would be low. The system would cool some, but not well.
|| || || || || || || || || || || ||
17-22) What system operating characteristics would you expect from a system which has a
|| || || || || || || || || || || || || ||
restricted orifice type metering device? - ✔✔The suction pressure would be very low,
|| || || || || || || || || || || || ||
possibly in a vacuum. The superheat and subcooling would both be high. The system would
|| || || || || || || || || || || || || || ||
not cool.
||
, 2
17-23) What system operating characteristics would you expect from a system which has an
|| || || || || || || || || || || || || ||
oversized orifice type metering device? - ✔✔The suction pressure would be high. The head
|| || || || || || || || || || || || || ||
pressure would be low. The superheat and subcooling would both be low.
|| || || || || || || || || || ||
For most multi-box refrigeration systems, the liquid line sight glass would be located ______.
|| || || || || || || || || || || || ||
a) before the compressor suction line
|| || || || ||
b) after the compressor discharge
|| || || ||
c) upstream of the condenser
|| || || ||
d) downstream of the receiver - ✔✔D
|| || || || || ||
The function of a heat interchanger used in a refrigeration system is to ______.
|| || || || || || || || || || || || ||
a) lower the temperature of liquid refrigerant before entering the expansion valve
|| || || || || || || || || || ||
b) reduce the possibility of liquid refrigerant from flooding back to the compressor
|| || || || || || || || || || || ||
c) minimize sweating of the suction line
|| || || || || ||
d) All of the above. - ✔✔D
|| || || || || ||
An economizer, or heat interchanger, is installed in a refrigeration system to ______.
|| || || || || || || || || || || ||
a) reduce the possibility of sweating of the suction line
|| || || || || || || || ||
b) reduce the temperature of liquid refrigerant prior to entering the expansion valve
|| || || || || || || || || || || ||
c) reduce the possibility of liquid refrigerant flooding back to the compressor
|| || || || || || || || || || ||
d) all of the above - ✔✔D
|| || || || || ||
A liquid line economizer or heat exchanger in a refrigeration system, using a reciprocating
|| || || || || || || || || || || || || ||
compressor, functions to ______. || || ||
a) reduce the possibility of liquid refrigerant slugging the compressor
|| || || || || || || || ||
b) raise the temperature of liquid refrigerant
|| || || || || ||
c) cool the suction vapor returning to the compressor
|| || || || || || || ||
Refrigeration Test 4 with accurate detailed answers || || || || || ||
17-1) What happens to the refrigerant as it passes through the metering device? - ✔✔The
|| || || || || || || || || || || || || || ||
refrigerant drops in pressure and temperature as it passes through the metering device. A
|| || || || || || || || || || || || || ||
small portion of the refrigerant flashes to a vapor, cooling the remaining liquid.
|| || || || || || || || || || || ||
17-2) Explain the difference between a fixed metering device and a modulating metering
|| || || || || || || || || || || || ||
device. - ✔✔A fixed metering device cannot change to respond to system changes, a
|| || || || || || || || || || || || || ||
modulating metering device can. || || ||
17-3) What are the two types of fixed metering devices? - ✔✔Capillary tubes and orifices
|| || || || || || || || || || || || || ||
17-4) List the advantages of the capillary tube. - ✔✔The cap tube is simple, inexpensive,
|| || || || || || || || || || || || || || ||
and cap tube systems can be used with low starting torque compressors
|| || || || || || || || || || ||
17-5) Explain the basic operation of the automatic expansion valve - ✔✔The automatic
|| || || || || || || || || || || || ||
expansion valve is a refrigerant pressure regulator. It is controlled by a diaphragm which
|| || || || || || || || || || || || || ||
balances the evaporator pressure against an adjustable spring pressure.
|| || || || || || || ||
17-6) Why is the automatic expansion valve not suited for systems with varying loads? -
|| || || || || || || || || || || || || || ||
✔✔The response of the automatic expansion valve to load changes causes it to feed more
|| || || || || || || || || || || || || || ||
refrigerant when the load decreases and less refrigerant when the load increases.
|| || || || || || || || || || ||
17-7) Which way would the adjustment on top of an automatic expansion valve be turned
|| || || || || || || || || || || || || || ||
to increase the evaporator pressure? - ✔✔Clockwise
|| || || || || ||
17-8) What does a thermostatic expansion valve try to regulate and keep stable? -
|| || || || || || || || || || || || || ||
✔✔Superheat
,2
17-9) What is the difference between internally and externally equalized thermostatic
|| || || || || || || || || || ||
expansion valves? - ✔✔Internally equalized valves obtain the evaporator pressure through a
|| || || || || || || || || || || ||
passageway inside the valve. Externally equalized valves obtain evaporator pressure through
|| || || || || || || || || || ||
a separate line which runs from the valve to the suction line.
|| || || || || || || || || || ||
17-10) How does a TEV with MOP work? - ✔✔MOP valves have a gas charge. Gas charged
|| || || || || || || || || || || || || || || || ||
bulbs have only a small amount of liquid in the bulb. When the valves reaches the MOP,
|| || || || || || || || || || || || || || || || ||
maximum operating pressure, there is no more liquid in the bulb. This greatly limits the
|| || || || || || || || || || || || || || ||
bulb opening pressure.
|| ||
17-11) What is the difference between a traditional TEV and a balanced port TEV? - ✔✔A
|| || || || || || || || || || || || || || || ||
traditional TEV is affected by the pressure drop across the valve. Increased pressure
|| || || || || || || || || || || || ||
difference tends to open the valve more. A balanced port valve is designed to counteract
|| || || || || || || || || || || || || || ||
the effect of pressure difference across the valve, so the valve can retain good control at a
|| || || || || || || || || || || || || || || || ||
much wider range of operating conditions.
|| || || || ||
17-12) What is the difference between a traditional liquid charged TEV bulb and a liquid
|| || || || || || || || || || || || || || ||
cross-charged TEV bulb? - ✔✔A traditional charge uses the same refrigerant as is in the
|| || || || || || || || || || || || || || ||
system. A cross charged bulb contains a different refrigerant than the system, so the
|| || || || || || || || || || || || || ||
pressure response of the bulb crosses the pressure response of the system at some point.
|| || || || || || || || || || || || || ||
17-13) What is the purpose of a liquid distributor? - ✔✔A liquid distributor is used to
|| || || || || || || || || || || || || || || ||
evenly distribute the mixture of liquid and vapor refrigerant leaving
|| || || || || || || || ||
17-14) Which way would the adjusting stem on an expansion valve be turned to increase
|| || || || || || || || || || || || || || ||
the superheat? - ✔✔Clockwise
|| || ||
17-15) Which way would the adjusting stem on an expansion valve be turned to decrease
|| || || || || || || || || || || || || || ||
superheat? - ✔✔Counter clockwise || || ||
,2
17-16) What types of problems could cause a TEV system to operate at too high a
|| || || || || || || || || || || || || || || ||
superheat? - ✔✔System undercharge, liquid line refrigerant restriction, dead TEV power
|| || || || || || || || || || ||
element, TEV plugged with debris from brazing
|| || || || || ||
17-17) Why must technicians be careful when brazing lines to evaporator coils which have
|| || || || || || || || || || || || || ||
thermostatic expansion valves? - ✔✔The heat from brazing the lines can conduct through
|| || || || || || || || || || || || ||
the lines to the TEV bulb and destroy the bulb by building up very high pressure in the
|| || || || || || || || || || || || || || || || || ||
power head. ||
17-18) How can a capillary tube that is restricted with debris be differentiated from a
|| || || || || || || || || || || || || || ||
capillary tube that is restricted with ice? - ✔✔A capillary tube that is plugged with debris
|| || || || || || || || || || || || || || || ||
will immediately pull into a very low suction pressure or vacuum. Ice normally only forms
|| || || || || || || || || || || || || || ||
after the system has operated some and the evaporator starts getting cold.
|| || || || || || || || || || ||
17-19) What is a bi-flow expansion valve? - ✔✔A bi-flow expansion valve is designed to
|| || || || || || || || || || || || || || ||
allow refrigerant flow in both directions. Some bi-flow valves meter the refrigerant in both
|| || || || || || || || || || || || || ||
directions while others allow unrestricted flow in the reverse direction.
|| || || || || || || || ||
17-20) What system operating characteristics would you expect from a system which has a
|| || || || || || || || || || || || || ||
TEV with a dead power element? - ✔✔The suction pressure would be very low, possibly in
|| || || || || || || || || || || || || || || ||
a vacuum. The superheat and subcooling would both be high. The system would not cool.
|| || || || || || || || || || || || || ||
17-21) What system operating characteristics would you expect from a system which has a
|| || || || || || || || || || || || || ||
TEV with a loose sensing bulb? - ✔✔The suction pressure would be high. The superheat
|| || || || || || || || || || || || || || ||
and subcooling would be low. The system would cool some, but not well.
|| || || || || || || || || || || ||
17-22) What system operating characteristics would you expect from a system which has a
|| || || || || || || || || || || || || ||
restricted orifice type metering device? - ✔✔The suction pressure would be very low,
|| || || || || || || || || || || || ||
possibly in a vacuum. The superheat and subcooling would both be high. The system would
|| || || || || || || || || || || || || || ||
not cool.
||
, 2
17-23) What system operating characteristics would you expect from a system which has an
|| || || || || || || || || || || || || ||
oversized orifice type metering device? - ✔✔The suction pressure would be high. The head
|| || || || || || || || || || || || || ||
pressure would be low. The superheat and subcooling would both be low.
|| || || || || || || || || || ||
For most multi-box refrigeration systems, the liquid line sight glass would be located ______.
|| || || || || || || || || || || || ||
a) before the compressor suction line
|| || || || ||
b) after the compressor discharge
|| || || ||
c) upstream of the condenser
|| || || ||
d) downstream of the receiver - ✔✔D
|| || || || || ||
The function of a heat interchanger used in a refrigeration system is to ______.
|| || || || || || || || || || || || ||
a) lower the temperature of liquid refrigerant before entering the expansion valve
|| || || || || || || || || || ||
b) reduce the possibility of liquid refrigerant from flooding back to the compressor
|| || || || || || || || || || || ||
c) minimize sweating of the suction line
|| || || || || ||
d) All of the above. - ✔✔D
|| || || || || ||
An economizer, or heat interchanger, is installed in a refrigeration system to ______.
|| || || || || || || || || || || ||
a) reduce the possibility of sweating of the suction line
|| || || || || || || || ||
b) reduce the temperature of liquid refrigerant prior to entering the expansion valve
|| || || || || || || || || || || ||
c) reduce the possibility of liquid refrigerant flooding back to the compressor
|| || || || || || || || || || ||
d) all of the above - ✔✔D
|| || || || || ||
A liquid line economizer or heat exchanger in a refrigeration system, using a reciprocating
|| || || || || || || || || || || || || ||
compressor, functions to ______. || || ||
a) reduce the possibility of liquid refrigerant slugging the compressor
|| || || || || || || || ||
b) raise the temperature of liquid refrigerant
|| || || || || ||
c) cool the suction vapor returning to the compressor
|| || || || || || || ||
