RMO REVIEW 1 Flashcards
1. What refrigerant systems are most likely to leak refrigerant in building spaces that are being cooled? A. Indirect Systems B. Direct Systems C. Indirect Closed Systems D. Indirect Open Systems
B. DIRECT SYSTEM
- An operator has been assigned to a large reciprocating machine without unloaders, of the following safety proper procedures for starting this machine is
A. Filter suction and discharge valves
B. Suction valve and discharge bypass both open
C. Suction bypass and discharge valve both open
D. Discharge bypass and suction valve both closed
B. Suction valve and discharge bypass both open
- Upon being assigned to a facility during inspection of the facility, you find there has been failure to maintain water treatment. Inspecting the condenser water, the first evidence would most likely be:
A. Decrease in super heat temp entering compressor
B. An increase in compressor head pressure
C. An increase in the flow rate of non-condensables
D. Condenser to metering device line frozen
B. An increase in compressor head pressure
4. During a particular round an operator notices that the suction line and part of the compressor are frosted. The most likely cause of the condition is: A. Not enough refrigerant in the system B. Expansion valve open to wide C. The compressor is running continually D. Compressor valves are leaking
A. Not enough refrigerant in the system
5. When charging an R-22 reciprocating refrigeration system, an operator would want to use warm water to increase the release rate of refrigerant from the drum. To perform this operation the water temp should not exceed the degree F of: A. 80 F B. 90 F C. 110 F D. 130 F
B. 90 F
6. With respect to fire safety ANSI/ASHRAE refrigerant safety classification that is most dangerous is: A. A1 B. B2 C. A3 D. B1
C. A3
- At the condenser, refrigerant enters as:
A. High pressure gas and leaves as low pressure liquid
B. High pressure gas and leaves as high pressure liquid
C. Superheated gas and leaves as high temperature liquid
D. High temperature gas and leave as superheated gas
C. Superheated gas and leaves as high temperature liquid
8. According to NYC fire code classification of refrigeration, Ammonia would fall under which group? A. Group 1 B. Group 2 C. Group 3 D. Group 4
B. Group 2
- In an electric motor is rewound to cut resistance by ½ , all other factors being equal, the motor power would
A. Reduced by ½
B. increase by a factor of 2
C. Stay the same
D. Increase by a factor of 4
B. increase by a factor of 2
- Assuming an operator is able to observe R-11, water and lubricating oil together at 70F. Under these conditions, the water, moisture and fluids would settle in the container from top to bottom in what order?
A. Water, oil and refrigerant
B. Oil, refrigerant and water
C. Refrigerant oil and water
D. Oil, water and refrigerant
D. Oil, water and refrigerant
- A reciprocating refrigerant compressor cylinder has a 12” bore and a 16” stroke. The volume of refrigerant in cubic inches would be closer to:
A. 1204
B. 1002
C. 1808
D. 1406
C. 1808
- You have been informed that the outside temperature has been dropped by 10 C the temperature in degrees F is:
A. 32
B. 28
C. 40
D. 18
D. 18
- An automatic purge unit is required for those refrigerating systems that have:
A. Double indirect open space systems
B. System operating below atmospheric pressure
C. Absorption compressors
D. Outside air dampers
B. System operating below atmospheric pressure
- Orifice plates may be used as a metering device component in a centrifugal system. The vessel which they are contained in, can also serve as:
A. A vapor recycling unit
B. An economizer
C. A refrigerant cleaner
D. A condenser
B. An economizer
- A rupture disc in a centrifugal refrigerating machine is normally located on the:
A. Condenser
B. Economizer
C. Compressor discharge
D. Evaporator
D. Evaporator
- A pump affects the pressure of a fluid or gas by:
A. Reducing pressure
B. Raising pressure
C. Regulating pressure
D. Stabilizing pressure
B. Raising pressure
- An operator is running two centrifugal condenser water pumps in parallel, one of the pumps is at maximum pumping rate, if the operator throttles back on the discharge valve of the other pump, the most likely effect would be:
A. A reduction on both the water flow rate and pressure into the condenser
B. A reduction in total flow rate to condenser
C. A reduction in water pressure at the condenser inlet
D. For the pumps to compensate to maintain both the flow rate and the discharge pressure
B. A reduction in total flow rate to condenser
- As an RMO in charge, you are required to replace the gauge on the high side of the refrigeration system. The pressure graduation rate should be:
A. 1.2 of the designed pressure (at least)
B. The rupture guard has to be a replaced also
C. The gauge has to be a compound gauge
D. The gauge should be graduated to pressure
A. 1.2 of the designed pressure (at least)
- When operating a refrigeration unit, the operator notices that the motor compressor is short cycling, the unit is using a low side float valve. The following service requirements would indicate:
A. Inspections should be made for dirty TEV strainer
B. Partially clogged discharge line
C. Checking compressor wires for overloaded equipment
D. Additional refrigerant be charged
D. Additional refrigerant be charged
- Of the following the most correct way to describe a brazed joint is
A. Pressure fitting
B. Gas tight fitting
C. Start to melt at 400 F
D. Start to melt at 500 F
B. Gas tight fitting
- You are the RMO assigned to the 3rd floor in an assembly room. Attendance and temp have increased during the afternoon, therefore a colder water supply is to be produced in order to accomplish this you should:
A. Re-adjust the TEV superheat setting
B. Deactivate the freeze stat
C. Raise the compressor discharge operating pressure
D. Lower the compressor suction operating pressure
D. Lower the compressor suction operating pressure
- Of the following the most undesirable property in refrigerant is:
A. Low corresponding compressor discharge temp
B. Low viscosity
C. Low latent heat
D. Low corresponding operating pressure
C. Low latent heat
- When conducting a routine tour of plant operation a RMO observes a significant increase in superheat temperature. For the refrigerating fluid entering a reciprocating compressor of the following the most likely cause for this condition is:
A. Scale particles lodged in the TEV valve
B. Unraveling of the insulation protecting the TEV valve thermal bulb
C. Build-up of the non-condensables in the condenser
D. Overcharge of refrigerant
C. Build-up of the non-condensables in the condenser
- While monitoring the operation of a reciprocating refrigerating unit you over see that the cycling times are normal, compressor compression and temp are the only readings that are outside the normal rate. Under these conditions service requirements would indicate inspecting for:
A. Faulty machine controls
B. Proper refrigeration charge
C. Faulty compressor valves
D. Poor compressor operation / Dirty tubes
A. Faulty machine controls
- You are a RMO assigned to facility where a refrigerant has been recently changed to from flammable refrigerant to R-22, at the moment you are planning to braze metal. On such making a repair in the machinery room, under these circumstances you:
A. Must ensure the flame is enclosed and vented to open air
B. May make repairs at least 25 ft from the refrigerant unit
C. May make repairs without any restrictions if the refrigerating unit is shut down
D. May not make repairs under any circumstances
C. May make repairs without any restrictions if the refrigerating unit is shut down
- A RMO needed to vary the flow of refrigerant in a system. A continuous variation in the flow of the system does not included the:
A. Solenoid valve
B. High side float
C. Thermal expansion valve
D. Capillary tube
A. Solenoid valve
- An operator has been assigned to run a reciprocating compressor. Of the following, action capacity control would most likely be achieved through:
A. Opening the suction valves with some form of control
B. Controlling discharge pressure
C. Changing the stroke and adding re-expansion volume
D. Returning the discharge gas suction
A. Opening the suction valves with some form of control
- An operator is using a sling psychrometer to measure dry and wet bulb temperatures on a roof of a building where cooling tower is located. If during the day the temperature remains constant and the wet bulb drops by 5 F and all other conditions remain unchanged. The operator should see:
A. Higher cooling water being returned
B. Rise in condenser head temperature
C. Lower cooling water temperature returned
D. No noticeable effect of the cooling water temperature being returned
C. Lower cooling water temperature returned
- A RMO would expect a relief valve to start functioning (For the section of refrigerating system being protected) at a pressure most closest to:
A. 5% over the design pressure
B. The design pressure
C. Recommended operating pressure for normal cooling conditions
D. 20% below the design pressure
B. The design pressure
- It the eliminator plates located below the fan in an induced draft-cooling tower have become clogged, of the following this would most likely result in:
A. Damage to fan blades
B. Increase in cooling tower water temperature being returned
C. Decrease in make-up water requirements
D. A drop in wet bulb temperature
B. Increase in cooling tower water temperature being returned
- Convert 18” vacuum to PSIA
A. 7.7
B. 0.6
C. 5.9
D. 23.5
C. 5.9
- Superheated vapor protects the compressor against liquid intake. What would the RMO notice if the compressor was receiving liquid?
A. Head PSI dropping to low
B. Decrease the capacity of the compressor and refrigeration system
C. Non-condensables are more prone to collect in the system
D. Frost may develop in the suction line
B. Decrease the capacity of the compressor and refrigeration system
- A RMO was instructed to charge a 60 ton plant with R-134a refrigerant. The operator would most likely find the charging valve on the:
A. High pressure side of the equipment
B. Low pressure side of the equipment
C. Discharge side of the equipment
D. Receiver
B. Low pressure side of the equipment
- When properly purging, you should:
A. Purge at a rapid rate
B. Purge with compressor on
C. Stop when compressor ceases to drop
D. Run the compressor as much as possible
B. Purge with compressor on
- Given a refrigeration system which includes a forced draft cooling tower, an economizer and chilled water as the cooling medium, the heat that is removed from the building is finally rejected:
A. As heated of evaporation of the cooling tower
B. In the economizer
C. In the evaporator
D. In the condenser water outlet
A. As heated of evaporation of the cooling tower
- Which is not used as a cooling medium in an indirect system?
A. R-22
B. Calcium chloride
C. Glycol
D. Sodium chloride
A. R-22
- In a refrigeration plant, a small induction refrigeration motor is running a AC current. In order for the operator to determine the true power consumption , assuming every eligible characteristics have been met. Of the following, the power consumption is determined by the application of the formula:
A. Watts = volts x amps x ohms
B. Watts = volts x amps x hertz
C. Watts = volts x amps
D. Watts = volts x amps x power factor
D. Watts = volts x amps x power factor
- Of the following, which refrigerant requires the approval for use by the NYC Fire Dept.
A. R-22
B. R-12
C. Carbon dioxide
D. Butane
D. Butane
- When installing a service valve to isolate a dual pressure device while keeping the system in service, you would use a:
A. Two way valve
B. Three way valve
C. Plug valve
D. Stop valve
B. Three way valve
- The solenoid unloaders on reciprocating compressors are designed to unload:
A. All the cylinders
B. The clearance spaces in the cylinder
C. Control capacity by shutting down the compressor
D. Cylinders that can be unloaded
B. The clearance spaces in the cylinder
- Efficiency of the refrigeration cycle is affected by the operation of the condenser. Of the following a more efficient operation of a centrifugal compressor results from:
A. Raise the condenser liquid level to the maximum
B. Produce a large amount of liquid subcooling
C. Raise the condenser head pressure
D. Lower the condenser pressure
D. Lower the condenser pressure
- Of the following, under what conditions of the heat in BTU’s/ per min absorbed by condenser water in a refrigerating plant is greater.
A. At higher evaporative temperatures and low condensing temperatures
B. At low evaporative temperatures and high condenser temperatures
C. At higher evaporative temperatures and high condenser temperatures
D. At low evaporative temperatures and low condenser temperatures
B. At low evaporative temperatures and high condenser temperatures
- Assume that the operator has a choice of 4 valves to select from and wants to minimize pressure drop, of the following the operator should avoid the use of the:
A. Ball valve
B. Plug valve
C. Globe valve
D. Gate valve
C. Globe valve
- In an emergency if you must dump refrigerant into the sewer. You will dump only when:
A. Sewer is not connected to a storm drain
B. First confirm that the refrigerant is not flammable
C. Facility manager approves it
D. You discharge under the supervision of the Fire Dept
D. You discharge under the supervision of the Fire Dept
- Due to a cold front, there was a sharp drop in outside temperature. The most likely effect of this condition on the operation of the reciprocating machine would be that the thermostat causes solenoid valve to:
A. Close and the compressor will pump down and shuts down on the low pressure
B. Close and the compressor will start on high pressure
C. Open and the compressor will pump down and go off on high pressure
D. Open and the compressor will continue to run at a reduced speed
A. Close and the compressor will pump down and shuts down on the low pressure
- A jet ejector is used to raise oil mixed with refrigerant which has collected at the bottom of the evaporator. If restricted:
A. The flow of oil will not be effected
B. You will have insufficient head to lift the oil
C. The temperature of the refrigerant exiting the jets will decrease
D. The oil in the bottom of the chiller will not lift if it becomes mixed with less refrigerant
B. You will have insufficient head to lift the oil
- Low condensing pressure is not good because:
A. Liquid level in the condenser will fall to low
B. Compressor will work harder
C. Expansion valves will not feed properly
D. Head pressure will increase
C. Expansion valves will not feed properly
- Heat transfer rate in the condenser will:
A. Increase with the velocity of the water in the tubes
B. Show only a small increase if tubes are descaled
C. Increase with a lower leaving water temperature difference
D. Show the least benefit for descaling the tubes at high water velocities
A. Increase with the velocity of the water in the tubes
- Why should you charge with a vapor?
A. You can break the rupture guard with liquid
B. You can entrain the oil in the refrigerant with liquid
C. You can freeze water in the tubes with liquid
D. You can over charge the system with liquid
C. You can freeze water in the tubes with liquid
- An inline refrigerant cleaning system is advisable because:
A. Non-condensables cannot be properly purged
B. Refrigerants react with lubrication oil
C. Refrigerant systems are high pressure
D. Refrigerant is a toxic class
A. Non-condensables cannot be properly purged
- R-22 is:
A. Odorless
B. Ether like in odor when mixed with air
C. Explosive
D. Boils at a higher temperature than R-12
A. Odorless
- At the plant where you are employed, a refrigerating unit is being taken out of service for major repairs and that you have been assigned to withdraw refrigerant for storage in a 40 gallon container. According to the NYC Fire Law Handbook, the maximum quantity of refrigerant in gallons that you may legally fill each container with, under any circumstances is:
A. 36
B. 30
C. 24
D. 32
B. 30
- When operating a refrigeration machine condenser using R-22 refrigerant, under normal conditions the operator observes that the cooling water is being supplied at 85 F and leaving at 95 F. Given this information, the corresponding compressor head pressure in PSI should be most nearly:
A. 113
B. 213
C. 313
D. 13
C. 313
- A vertical 12” water pipe from the roof has a pressure gauge reading of 120 psi. How tall is the pipe?
A. 277 feet
B. 1440 inches
C. 1440 feet
D. 277 inches
A. 277 feet
- If the suction pressure is 60 psig and the discharge is 180 psig, what would be the compression ratio be?
A. 5 : 1
B. 3 : 1
C. 2.6 : 1
D. 0.3 : 1
C. 2.6 : 1
- Of the following, the most common metering device used today in a reciprocation commercial refrigeration system over 3 tons is:
A. Automatic expansion valves
B. Thermostatic expansion valves
C. Low side float
D. High side float
B. Thermostatic expansion valves
- An RMO observes a gauge that reads the saturation pressure of a refrigerant. If the chiller water is being circulated as the cooling medium, this reading can best be used to estimate the:
A. Chilled water temperature returning from the building spaces being cooled
B. Temperature of the chilled water being pumped to the building spaces that are being cooled
C. Pressure of the chilled water being pumped to the building spaces that are being cooled
D. Cooling tower efficiency
B. Temperature of the chilled water being pumped to the building spaces that are being cooled
- Machine room safety standards have been established by:
A. ARI-700
B. ARI-740
C. ASHRAE 34
D. ASHRAE 15
D. ASHRAE 15
- R-11 and R-123 refrigerants are:
A. Oxygen depleting
B. Heavier than air
C. Are Class 1 and Class 2 substances defined by EPA
D. All of the above
D. All of the above
- What is the TEV diaphragm made of?
A. Rubber
B. Metal
C. Plastic
D. Graphite
B. Metal
- A RMO notices a knocking reciprocating compressor. The RMO is assured the compressor has no worn parts. The most probable cause of the knocking is:
A. Inadequate lubrication
B. Liquid slugging to the compressor
C. Crankcase pressure is low
D. Suction and discharge are not opening and closing
B. Liquid slugging to the compressor
- 1,000 BTU’s are removed from 100 pounds of water at a temperature of 55 F. What is the final water temperature?
A. 55 F
B. 50 F
C. 45 F
D. 40 F
C. 45 F
- An operator is using a portable recovery vessel and compressor to recover vapor refrigerant from a machine. The recovery process will slow down because:
A. Compressor capacity will decrease
B. Vapor density will increase
C. The refrigerant temperature will decrease
D. The refrigerant pressure will decrease
D. The refrigerant pressure will decrease
- Multistage centrifugal compressor each stage:
A. Tip speed is more with each stage
B. Every stage is identical
C. Handles more refrigerant
D. Has a smaller volume
D. Has a smaller volume
- Why is a spring loaded PRV better to use than a fusible plugs?
A. Less expensive
B. Easy availability
C. Fusible plug cannot be reset
D. Larger
C. Fusible plug cannot be reset
- What would happen if the spring in the TEV were to break?
A. Flood the evaporator
B. Starve the evaporator
C. No charge
D. Damage feeler bulb
A. Flood the evaporator
- If you were running three compressors, which best describes the state of the refrigerant leaving the third compressor?
A. Mostly liquid, some vapor
B. Mostly vapor, some liquid
C. Slightly superheated vapor
D. Slightly superheated liquid
D. Slightly superheated liquid
- What is the purpose of the equalizer line?
A. To equalize pressure in the TEV along the diaphragm
B. To make up for the pressure drop in the evaporator
C. To meter refrigerant
D. To remove pressure drop
B. To make up for the pressure drop in the evaporator
- In a compressor’s electrical box one of the hot wires is touching the metal box. What would most likely happen?
A. Compressor would overheat
B. Compressor would overload and shut off
C. RMO workers can receive an electric shock if they touching it
D. Nothing
B. Compressor would overload and shut off
- When installing a pipeline and you need to make a 90 degree elbow, which is the best way?
A. Bend pipe
B. Use factory made 90 degrees elbows and braze
C. Use flexible tubing
D. Use two 45 degrees elbows
B. Use factory made 90 degrees elbows and braze
- What is the purpose of having service valve stem cap?
A. To protect from being inadvertently turned from its position and being damaged
B. To let you know the position of the valve
C. To let you notice the valve from a distance
D. To cap off the valve so that it can never be used
A. To protect from being inadvertently turned from its position and being damaged
- One disadvantage in using brines as a cooling medium is corrosion. In commercial practice corrosion and the amount of rust formed is reduced by the addition to the brine solution of:
A. A weak acid solution
B. Zinc compounds
C. Glycols
D. Di-chromates
D. Di-chromates
- If you just purchased a thermometer and need to check to see if it’s working properly, how would you do it?
A. Touch it to a pot of boiling water
B. Touch it to a bucket of ice water
C. Compare to 2 other thermometers
D. Compare to another thermometer
B. Touch it to a bucket of ice water
- A bimetal disk, or Klixon is used:
A. Stop the refrigeration equipment before excessive pressure occurs
B. Stop the refrigeration equipment at a predetermined minimum operating pressure
C. Protect wiring and components against excessive current flow
D. Protect the compressor against the loss of oil pressure
C. Protect wiring and components against excessive current flow
- If you are using a portable compressor recovery unit to remove vapor, what would happen when you are recovering?
A. Compressor speed is decreased
B. Vapor density is decreased
C. Refrigerant temperature will drop
D. Compressor efficiency is decreased
C. Refrigerant temperature will drop
- The amount of refrigerant that flows through the orifice plate is determined by the:
A. Number of economizer stages
B. Number of compression stages
C. Temperature of refrigerant in the high side
D. Difference in pressure between the high and low sides
D. Difference in pressure between the high and low sides
- Unloaders are used to:
A. Increase capacity
B. Stop flow of refrigerant without stopping compressor
C. Reduce the capacity
D. Start flow of refrigerant through system
C. Reduce the capacity
- Semi-hermetic compressors may be better to use than hermetic compressors, because hermetic compressors because hermetic compressors:
A. Are fully enclosed and cannot be serviced on site
B. Are easier to get to
C. Are more difficult to get to
D. Are more expensive
A. Are fully enclosed and cannot be serviced on site
- A room thermostat controls the liquid line solenoid valve in this commercial refrigerant system. The compressor is activated by:
A. The high pressure cut in
B. The low side pressure stat
C. The thermostatic expansion valve
D. The thermostat that activates the solenoid valve
B. The low side pressure stat
- Which of the following ASHRAE safety groups is the most dangerous?
A. A1
B. A2
C. B2
D. B3
D. B3
- An operator has been assigned to run a centrifugal compressor of the following actions a capacity control is most likely to achieve is through:
A. Bypass discharge gas
B. Adjustment of the impeller inlet guide pre-rotation vanes
C. Condenser pressure variation
D. Adding re-expansion volume
B. Adjustment of the impeller inlet guide pre-rotation vanes
- As the RMO assigned to the facility you are instructed to store additional refrigerant drown in the machinery room. During cold weather, to eliminate the need for a drum to warm up prior to recharging the refrigerating unit. If there is a total of 1000 lbs of refrigerant that has been charged to a refrigeration machine, according to the NYC Fire Law Handbook, the maximum quantity in pounds you may legally store in the room is:
A. 1000 lbs
B. 100 lbs
C. 200 lbs
D. 300 lbs
C. 200 lbs
- When charging a system with liquid refrigerant with a set of manifold gauges, what position are the valves on the manifold?
A. High and low side valves are backseated
B. High and low side valves are frontseated
C. High side is backseated, low side frontseated
D. High side is frontseated, low side backseated
C. High side is backseated, low side frontseated
- On the liquid line, which is the correct order of the placement of the accessories?
A. Solenoid valve, sight glass and drier
B. Drier, sight glass and solenoid valve
C. Drier, solenoid valve and sight glass
D. None of the above
C. Drier, solenoid valve and sight glass
- TXV power heads are color coded to match refrigerant charge in the system. What color would the power head have if it was charged with R-22?
A. Orange
B. Green
C. Yellow
D. White
B. Green
- According to the safety Handbook, how much refrigerant can be recovered into a 60 lbs container?
A. 60 lbs
B. 45 lbs
C. 30 lbs
D. 15 lbs
B. 45 lbs
- During a walk-through of the engine room the RMO notices excessive superheat at the evaporator outlet, this would most likely be caused by:
A. Starve the evaporator
B. Leak in the system
C. Low refrigerant charge
D. Any of the above
D. Any of the above
- In an operating plant using reciprocating compressors, the efficiency of one of the compressors has decreased. Which one of the following may be the cause of this.
A. Light suction valve spring
B. High suction pressure
C. Leak in the suction valve
D. Low suction pressure
C. Leak in the suction valve
- What safety group does ammonia belong to?
A. Group 2, B2
B. Group 1, A1
C. Group 3, B1
D. Both A1 and B1
A. Group 2, B2
- Which type of pump is considered a non-positive displacement pump?
A. Reciprocating
B. Rotory, screw
C. Scroll
D. Centrifugal
D. Centrifugal
91. When changing water to ice, what must be removed? A. Specific heat B. Superheat C. Latent heat D. Sensible heat
C. Latent heat
- Frost appearing on the suction line and part of the compressor is caused by:
A. Slugging compressor
B. Flooded evaporator
C. Starved evaporator
D. Uninsulated suction line
B. Flooded evaporator
- The bulb to a TXV has fallen off and the room is at 85 F the evaporator would:
A. Starve
B. Flood
C. Increase superheat
D. Respond normally
B. Flood
- What is the disadvantage of having a low head pressure?
A. Evaporator would flood
B. Compressor would hunt
C. Expansion valve will not feed properly
D. Condenser could not sub-cooled
C. Expansion valve will not feed properly
- A constant pressure expansion valve is being used instead of a thermostatic explansion valve under various loads will:
A. Starve the evaporator
B. Flood the evaporator
C. Operate better than TEV
D. Both A and B are correct
D. Both A and B are correct
- A pressure relief valve that is installed on a reciprocating compressor using R-12 is normally set:
A. According to design pressure
B. According to operating pressure
C. Lower than the high pressure cut out
D. At lower pressure cut out plus 50%
A. According to design pressure
- Assuming all conditions remain constant, the HP per ton of refrigerating effect woud most likely:
A. Decreases as the suction pressure increases
B. Increases as the suction pressure increases
C. Decreases as the discharge pressure increases
D. Increases as the discharge pressure decreases
A. Decreases as the suction pressure increases
- Refrigerants are characterized by the physical and chemical properties including latent heat, boiling point, refrigerating effect others. Of the refrigerants in commercial industries used today, the one with the highest latent heat refrigeration effect is:
A. R-12
B. Carbon dioxide
C. Ammonia
D. R-22
C. Ammonia
- A motor has 4 belts, the center belt is worn, you would:
A. Change the center belt
B. Change the center belt and all other belts
C. Change the other belts
D. Change to direct drive system
B. Change the center belt and all other belts
- If a centrifugal compressor is being used in a refrigeration system, and is affected by condenser, the condenser may be improved by:
A. Increasing the amount of superheat
B. Increasing the amount of sub-cooling
C. Decreasing the amount of superheat
D. Decreasing the amount of sub-cooling
B. Increasing the amount of sub-cooling
