RMO WRITTEN EXAM QUESTIONS & ANSWERS
How do automatic expansion valves work? - Answers :Evaporator pressure closes the
valve and spring pressure opens the valve.
When will a faulty check valve cause the most damage? - Answers :On startup.
What will happen if a TEV'S sensing bulb insulation wears off of the suction line in an 85
F Degree room? - Answers :You will flood the evaporator.
What can a clogged pump strainer cause? - Answers :A reduction or loss in water flow
which will lead to high condenser head pressure.
What part of the Refrigeration system is the solenoid valve part of? - Answers :The
pump down cycle (Thermostat - Solenoid Valve - Low Pressure Controller).
What is the proper machine start up procedure? - Answers :Check oil, start chilled water
pump, start condenser water pump, start tower fans and start up machine.
What is the main reason for installing an oil separator on the discharge line? - Answers
:To return oil back to the compressor crank case.
What causes the foaming of oil in a reciprocating compressor using the splash system
for lubrication? - Answers :A rapid decrease in pressure.
What is the purpose of oil in a refrigerant compressor? - Answers :It reduces ware and
friction.
What is a filter dryer used to remove? - Answers :Moisture, particles and contaminants.
Where in a refrigeration system is the oil separator located? - Answers :On the
discharge line as far from the compressor as possible.
If a motor has 4 belts and 1 of the 4 belts are worn, how many belts should be
replaced? - Answers :All of the belts should be replaced.
Does a solenoid valve vary or control the flow of refrigerant? - Answers :No.
What accessory meters and controls the flow of refrigerant into the evaporator? -
Answers :The TEV (Metering Device).
What will occur if you use an automatic expansion valve with a variable load? - Answers
:You will starve the evaporator.
What does an automatic expansion valve do? - Answers :It maintains a constant
evaporator pressure.
,What could cause the evaporator to not respond to the adjustments of the TEV? -
Answers :Oil logged on the low side.
What can non-condensible's cause? - Answers :High head pressure.
When will compressor motor horsepower increase? - Answers :It will increase as the
head pressure increases.
When will compressor motor horsepower decrease? - Answers :As the suction pressure
increases.
When using a brine solution in a system what can be used to prevent rusting? -
Answers :Di-Chromate Tablets.
What would cause a Halide torch flame to turn yellow? - Answers :A clogged sample
tube.
What is the purpose of having 2 compressors in a cascade system? - Answers :To
operate and very low temperatures and avoid high compression ratio.
Why is a pressure relief valve better than a fusible plug? - Answers :Because it can be
re-seated and is cost efficient.
What could cause compressor knocking? - Answers :Liquid refrigerant slugging the
compressor.
What would occur if a TEV'S spring were to break? - Answers :It would flood the
evaporator and raise the suction pressure because a TEV uses spring pressure as its
closing force. Thus, if the spring does not close the TEV refrigerant will constantly be
metered into the evaporator.
What is the purpose of the TEV equalizer line? - Answers :It compensates for the
pressure drop in the evaporator. Simply put, it equalizes pressure drop lost across the
evaporator.
What should be done when installing copper pipe and a 90 degree elbow is needed? -
Answers :You should BRAZE in a FACTORY MADE 90 degree elbow.
What is the purpose of a service valve stem cap? - Answers :It protects the valve from
refrigerant leakage.
What advantage do semi hermetic compressor's have over hermetic compressor's? -
Answers :Semi hermetic compressor's can be serviced.
, What happens when using portable compressor recovery unit to remove vapor? -
Answers :The vapor density is decreased.
What is the purpose of an unloader? - Answers :To decrease capacity (capacity
control).
What determines the amount of pressure that flows through the orifice plates? -
Answers :The difference in pressure between the high side and the low side of the
system.
How does a reciprocating machine cycle compressors on and off? - Answers :Through
the use of the low pressure control.
What refrigerant has the best Refrigeration effect and highest latent heat? - Answers
:Ammonia (R-717) / ASHRE Classification is B2.
What is the leaving water temperature of an induced draft cooling tower that is operating
efficiently? - Answers :At some temperature between the dry and wet bulb temperature.
What could a sudden reduction in the supply flow of the cooling tower water result in? -
Answers :An increase in head pressure.
How do reciprocating compressor unloaders operate? - Answers :By keeping the
compressor suction valves open.
Which side of the compressor is R-22 vapor charged into? - Answers :The suction side.
What should the percentage of lubricant circulated through a well designed system be?
- Answers :Lubricant should not exceed 10%.
What is oil foaming in the compressor a result of? - Answers :Liquid refrigerant in the
crankcase.
How can you check proper operation of a thermometer? - Answers :Local 94 answer -
Place it in a container with ice water.
Turner answer - Place it on an open container of boiling water.
How many phases will a 3 HP motor use? - Answers :3 Phases.
If you were running 3 compressors what would the state of the refrigerant be leaving the
3rd evaporator coil? - Answers :It would be a slightly superheated vapor.
What does a TEV do? - Answers :It restricts the amount of refrigerant that flows from
the high side to the low side.
How do automatic expansion valves work? - Answers :Evaporator pressure closes the
valve and spring pressure opens the valve.
When will a faulty check valve cause the most damage? - Answers :On startup.
What will happen if a TEV'S sensing bulb insulation wears off of the suction line in an 85
F Degree room? - Answers :You will flood the evaporator.
What can a clogged pump strainer cause? - Answers :A reduction or loss in water flow
which will lead to high condenser head pressure.
What part of the Refrigeration system is the solenoid valve part of? - Answers :The
pump down cycle (Thermostat - Solenoid Valve - Low Pressure Controller).
What is the proper machine start up procedure? - Answers :Check oil, start chilled water
pump, start condenser water pump, start tower fans and start up machine.
What is the main reason for installing an oil separator on the discharge line? - Answers
:To return oil back to the compressor crank case.
What causes the foaming of oil in a reciprocating compressor using the splash system
for lubrication? - Answers :A rapid decrease in pressure.
What is the purpose of oil in a refrigerant compressor? - Answers :It reduces ware and
friction.
What is a filter dryer used to remove? - Answers :Moisture, particles and contaminants.
Where in a refrigeration system is the oil separator located? - Answers :On the
discharge line as far from the compressor as possible.
If a motor has 4 belts and 1 of the 4 belts are worn, how many belts should be
replaced? - Answers :All of the belts should be replaced.
Does a solenoid valve vary or control the flow of refrigerant? - Answers :No.
What accessory meters and controls the flow of refrigerant into the evaporator? -
Answers :The TEV (Metering Device).
What will occur if you use an automatic expansion valve with a variable load? - Answers
:You will starve the evaporator.
What does an automatic expansion valve do? - Answers :It maintains a constant
evaporator pressure.
,What could cause the evaporator to not respond to the adjustments of the TEV? -
Answers :Oil logged on the low side.
What can non-condensible's cause? - Answers :High head pressure.
When will compressor motor horsepower increase? - Answers :It will increase as the
head pressure increases.
When will compressor motor horsepower decrease? - Answers :As the suction pressure
increases.
When using a brine solution in a system what can be used to prevent rusting? -
Answers :Di-Chromate Tablets.
What would cause a Halide torch flame to turn yellow? - Answers :A clogged sample
tube.
What is the purpose of having 2 compressors in a cascade system? - Answers :To
operate and very low temperatures and avoid high compression ratio.
Why is a pressure relief valve better than a fusible plug? - Answers :Because it can be
re-seated and is cost efficient.
What could cause compressor knocking? - Answers :Liquid refrigerant slugging the
compressor.
What would occur if a TEV'S spring were to break? - Answers :It would flood the
evaporator and raise the suction pressure because a TEV uses spring pressure as its
closing force. Thus, if the spring does not close the TEV refrigerant will constantly be
metered into the evaporator.
What is the purpose of the TEV equalizer line? - Answers :It compensates for the
pressure drop in the evaporator. Simply put, it equalizes pressure drop lost across the
evaporator.
What should be done when installing copper pipe and a 90 degree elbow is needed? -
Answers :You should BRAZE in a FACTORY MADE 90 degree elbow.
What is the purpose of a service valve stem cap? - Answers :It protects the valve from
refrigerant leakage.
What advantage do semi hermetic compressor's have over hermetic compressor's? -
Answers :Semi hermetic compressor's can be serviced.
, What happens when using portable compressor recovery unit to remove vapor? -
Answers :The vapor density is decreased.
What is the purpose of an unloader? - Answers :To decrease capacity (capacity
control).
What determines the amount of pressure that flows through the orifice plates? -
Answers :The difference in pressure between the high side and the low side of the
system.
How does a reciprocating machine cycle compressors on and off? - Answers :Through
the use of the low pressure control.
What refrigerant has the best Refrigeration effect and highest latent heat? - Answers
:Ammonia (R-717) / ASHRE Classification is B2.
What is the leaving water temperature of an induced draft cooling tower that is operating
efficiently? - Answers :At some temperature between the dry and wet bulb temperature.
What could a sudden reduction in the supply flow of the cooling tower water result in? -
Answers :An increase in head pressure.
How do reciprocating compressor unloaders operate? - Answers :By keeping the
compressor suction valves open.
Which side of the compressor is R-22 vapor charged into? - Answers :The suction side.
What should the percentage of lubricant circulated through a well designed system be?
- Answers :Lubricant should not exceed 10%.
What is oil foaming in the compressor a result of? - Answers :Liquid refrigerant in the
crankcase.
How can you check proper operation of a thermometer? - Answers :Local 94 answer -
Place it in a container with ice water.
Turner answer - Place it on an open container of boiling water.
How many phases will a 3 HP motor use? - Answers :3 Phases.
If you were running 3 compressors what would the state of the refrigerant be leaving the
3rd evaporator coil? - Answers :It would be a slightly superheated vapor.
What does a TEV do? - Answers :It restricts the amount of refrigerant that flows from
the high side to the low side.
