Refrigerant Machine Operator Certification Practice Test #1 Flashcards
The amount of refrigerant that flows through the orifice plate is determined by ____
A. THE NUMBER OF ECONOMIZER STAGES
B. THE NUMBER OF COMPRESSION STAGES
C. TEMPERATURE OF REFRIGERANT IN THE HIGH SIDE
D. DIFFERENCE IN PRESSURE BETWEEN HIGH AND LOW SIDES
Difference in pressure between high and low sides
Unloaders are used to
INCREASE CAPACITY
STOP FLOW OF REFRIGERANT WITHOUT STOPPING
REDUCE CAPACITY
START FLOW OF REFRIGERANT THROUGH SYSTEM
Reduce capacity
Semi-Hermetic compressors may be better to use than hermetic compressors because hermetic compressors ____
ARE FULLY ENCLOSED AND CANNOT BE SERVICED ON SITE
ARE EASIER TO GET TO
ARE MORE DIFFICULT TO GET TO
ARE MORE EXPENSIVE
Are fully enclosed and cannot be serviced on site
When conducting a routine tour of plant operation a RMO observes a significant increase in superheat temp. For the refrigerating fluid entering a reciprocating compressor. The most likely cause for this condition is ____
SCALE PARTICLES LODGED IN THE TEV VALVE
UNRAVELING OF THE INSULATION PROTECTING THE TEV VALVE THERMAL BULB
BUILD-UP OF NONCONDENSABLES IN THE CONDENSER
OVERCHARGE OF REFRIGERANT
Scale particles lodged in the TEV valve
A room thermostat controls the liquid line solenoid valve in the commercial refrigeration system. The compressor is activated by ____
THE HIGH PRESSURE CUT IN
THE LOW SIDE PRESSURE STAT
THE THERMOSTATIC EXPANSION VALVE
THE THERMOSTAT THAT ACTIVATES THE SOLENOID VALVE
The low side pressure stat
WHILE MONITORING THE OPERATION OF A RECIPROCATING REFRIGERATING UNIT YOU OVERSEE THAT THE CYCLING TIMES ARE NORMAL, COMPRESSOR COMPRESSION AND TEMP ARE THE ONLY READING THAT ARE OUTSIDE THE NORMAL RATE. UNDER THESE CONDITIONS SERVICE REQUIREMENTS WOULD INDICATE INSPECTING FOR
FAULTY MACHINE CONTROL
PROPER REFRIGERATION CHARGE
FAULTY COMPRESSOR VALVES
POOR CONDENSER OPERATION / DIRTY TUBES
Faulty compressor valves
Which of the following ASHRAE safety groups is the most dangerous
A1
A2
B2
B3
B3
You are an RMO assigned to a facility where a refrigerant has been recently changed from a 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 ____
MUST ENSURE THE FLAME IS ENCLOSED AND VENTED TO OPEN AIR
MAY MAKE REPAIRS AT LEAST 25 FEET FROM THE REFRIGERANT UNIT
MAY MAKE REPAIRS WITHOUT ANY RESTRICTIONS IF THE REFRIGERATING UNIT IS SHUT DOWN
MAY NOT MAKE REPAIR UNDER ANY CIRCUMSTANCES
Must ensure the flame is enclosed and vented to open air
An operator has been assigned to run a centrifugal compressor. Of the following actions a capacity control is most likely to achieve through _____
BYPASS DISCHARGE GAS
ADJUSTMENT OF THE IMPELLER INLET GUIDE PRE-ROTATION VANES
CONDENSER PRESSURE VARIATION
ADDING RE-EXPANSION VOLUME
Adjustment of the impeller inlet guide pre-rotation vanes
An RMO needs to vary the flow of refrigerant in the system. A continuous variation in the flow of the system does not include the ____
SOLENOID VALVE
HIGH SIDE FLOAT
THERMAL EXPANSION VALVE
CAPILLARY TUBE
Solenoid valve
An operator has been assigned to a large reciprocating machine without unloaders of the following, safety proper procedure for starting the machine is ____
FILTER SUCTION AND DISCHARGE VALVES
SUCTION VALVE AND DISCHARGE BYPASS BOTH OPEN
SUCTION BYPASS AND DISCHARGE VALVE BOTH OPEN
DISCHARGE BYPASS AND SUCTION VALVE BOTH CLOSED
Suction valve and discharge bypass both open
An operator has been assigned to run a reciprocating compressor. The following action capacity control would most likely be achieved through ____
OPENING THE SUCTION VALVES WITH SOME FORM OF CONTROL
CONTROLLING THE DISCHARGE PRESSURE
CHANGING THE STROKE AND ADDING RE-EXPANSION VOLUME
RETURNING THE DISCHARGE GAS TO SUCTION
Opening the suction valve with some form of control
If a centrifugal compressor is being used in a refrigerations system, and is affected by the condenser, the condenser may be improved by ____
INCREASING THE AMOUNT OF SUPERHEAT
INCREASING THE AMOUNT OF SUB-COOLING
DECREASE THE AMOUNT OF SUPERHEAT
DECREASE THE AMOUNT OF SUB-COOLING
Increasing the amount of subcooling
An operator is using a sling psychrometer to measure dry and wet bulb temp on a roof of a building where the cooling tower is located. If during the day the temp remains constant, and wet bulb drops by 5F, and all other conditions remain unchanged, the operator should see ____
HIGH COOLING WATER BEING RETURNED
RISE IN CONDENSER HEAD PRESSURE
LOWER COOLING WATER TEMPERATURE RETURN
NO NOTICEABLE EFFECT OF THE COOLING TOWER TEMP BEING RETURNED
Lower cooling water temperature return
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 should be ____
DECREASE IN SUPER HEAT TEMP ENTERING COMPRESSOR
AN INCREASE IN COMPRESSOR HEAD PRESSURE
AN INCREASE IN THE FLOW RATE OF NONCONDENSABLES
CONDENSER TO METERING DEVICE FROZEN
An increase in compressor head pressure
What is the purpose of the recovery tank when operating a refrigerant machine?
TO COOL THE REFRIGERANT
TO STORE EXCESS REFRIGERANT
TO FILTER IMPURITIES FROM THE REFRIGERANT
TO INCREASE COMPRESSOR EFFICIENCY
To store excess refrigerant
An RMO would expect a relief valve to start functioning (for the section of refrigerant one system being protected) at a pressure most closest to ____
5% OVER DESIGN PRESSURE
THE DESIGN PRESSURE
RECOMMENDED OPERATING PRESSURE FOR NORMAL COOLING CONDITIONS
20% BELOW DESIGN PRESSURE
The design pressure
When charging a system with liquid refrigerant with a set of manifold gauges, what position are the valves on the manifold?
HIGH AND LOW VALVES BACKSEATED
HIGH AND LOW VALVES FRONTSEATED
HIGH SIDE BACKSEATED, LOW SIDE FRONTSEATED
HIGH SIDE FRONTSEATED, LOW SIDE BACKSEATED
High side backseated, low side front seated
On the liquid line, which is the correct order of placement of the accessories?
SOLENOID VALVE, SIGHT-GLASS, AND DRIER
DRIER, SIGHT-GLASS, AND SOLENOID VALVE
DRIER, SOLENOID VALVE, AND SIGHT-GLASS
NONE OF THE ABOVE
Drier, solenoid valve, and sightglass
During a particular round an operator notices that the suction line and part of the compressor are frosted, the most likely cause of this condition is ____
NOT ENOUGH REFRIGERANT IN SYSTEM
EXPANSION VALVE OPEN TOO WIDE
THE COMPRESSOR IS RUNNING CONTINUALLY
COMPRESSOR VALVES ARE LEAKING
Expansion valve open too wide
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?
ORANGE
GREEN
YELLOW
WHITE
Green
When charging an R-12 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 of ____ F
80°F
90°F
110°F
130°F
90F
According to the safety handbook, how much refrigerant can be recovered into a 60 on container
60 LBS
45 LBS
30 LBS
15 LBS
45 lbs
During a walk through the engine room the RMO notices excessive superheat at the evaporator outlet, this would most likely be caused by ____
STARVED EVAPORATOR
LEAK IN SYSTEM
LOW REFRIGERANT CHARGE
ANY OF THE ABOVE
Any of the above
(Get the other answers)
In an operating plant using reciprocating compressors, the efficiency of one compressor has decreased. ____ may be the cause of this
LIGHT SUCTION VALVE SPRINGS
HIGH SUCTION PRESSURE
LEAK IN THE SUCTION VALVE
LOW SUCTION PRESSURE
Leak in the suction valve
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 ____
VAPOR RECYCLING UNIT
AN ECONOMIZER
REFRIGERANT CLEANER
EVAPORATOR
An economizer
With respect to the fire safety, the ANSI/ASHRAE refrigerant safety classification that is most dangerous is ____
A1
B2
A3
B1
A3
At the condenser the refrigerant enters as ____
HIGH PRESSURE GAS AND LEAVES AS LOW PRESSURE LIQUID
HIGH PRESSURE GAS AND LEAVES AS HIGH PRESSURE LIQUID
SUPERHEATED GAS AND LEAVES AS HIGH TEMPERATURE LIQUID
HIGH TEMPERATURE GAS AND LEAVES AS SUPERHEATED GAS
High pressure gas and leaves as high pressure liquid
What safety group does ammonia belong?
GROUP 2, B2
GROUP 1, A1
GROUP 3, B1
BOTH A1 AND B1
Group 2, B2
According to nyc fire code classification of refrigerant, ammonia would fall under which group?
GROUP 1
GROUP 2
GROUP 3
GROUP 4
Group 2
Which type of pump is considered non-positive displacement pump?
RECIPROCATING
ROTORY, SCREW
SCROLL
CENTRIFUGAL
Centrifugal
If 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 ____
DAMAGE TO FAN BLADES
INCREASE IN COOLING TOWER WATER TEMP BEING RETURNED
DECREASE IN MAKEUP WATER REQUIREMENTS
A DROP IN WET BULB TEMP
Increase in cooling tower water temp being returned
Convert 18” vacuum to psia
7.7
0.6
5.9
23.5
5.9
(Look up formula for conversion)
Superheated vapor protects the compressor against liquid intake. What would the RMO notice if compressor was receiving liquid?
HEAD PSI DROPPING TO LOW
DECREASE THE CAPACITY OF THE COMPRESSOR AND REFRIGERATION SYSTEM
NON-CONDENSABLES ARE MORE PRONE TO COLLECT IN THE SYSTEM
FROST MAY DEVELOP IN THE SUCTION LINE
Frost may develop in the suction line
If an electric motor is rewound to cut resistance by 1/2, all other factors being equal, the motor power would ____
REDUCE BY 1/2
INCREASE BY A FACTOR OF 2
STAY THE SAME
INCREASE BY A FACTOR OF 4
Increase by a factor of 2
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 HANDBOOK, THE MAXIMUM QUANTITY OF REFRIGERANT IN GALLONS THAT YOU MAY LEGALLY FILL EACH CONTAINER WITH UNDER ANY CIRCUMSTANCES IS ____
36
30
24
32
30 (that’s 75% max capacity)
An RMO was instructed to charge a 60 ton plant with R-134A refrigerant. The operator would most likely find the charging valve on the ____
HIGH PRESSURE SIDE OF THE EQUIPMENT
LOW PRESSURE SIDE OF THE EQUIPMENT
DISCHARGE SIDE OF THE EQUIPMENT
RECIEVER
Low pressure side of the equipment
When changing water to ice, what must be removed?
SPECIFIC HEAT
SUPER HEAT
LATENT HEAT
SENSIBLE HEAT
Latent heat
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 ____
113
313
213
13
213
(Look up reasoning)
When properly purging you should ____
PURGE AT RAPID RATE
PURGE WITH COMPRESSOR ON
STOP WHEN PRESSURE CEASES TO DROP
RUN THE CONDENSER AS MUCH AS POSSIBLE
Stop when pressure ceases to drop
A reciprocating refrigeration compressor cylinder HAS A 12” BORE AND 16” STROKE. THE VOLUME OF REFRIGERANT IN CUBIC INCHES WOULD BE CLOSER TO ____
1204
1002
1808
1406
1808
(Look up)
A rupture disc in a centrifugal refrigerating machine is normally located on the ____
CONDENSER
ECONOMIZER
COMPRESSOR DISCHARGE
EVAPORATOR
Evaporator
Initial OAT is 50F. You have been informed the OAT has dropped to 10C. The temperature in F is ____
32
28
40
18
32
(Look up formuler)
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 ____
AS HEAT OF EVAPORATION OF THE COOLING TOWER
IN THE ECONOMIZER
IN THE EVAPORATOR
CONDENSER WATER OUTLET
As heat of evaporation of the cooling tower
Frost appearing on the suction line an part of the compressor is caused by ____
SLUGGING COMPRESSOR
FLOODED EVAPORATOR
STARVED EVAPORATOR
UNINSULATED SUCTION LINE
Flooded evaporator
A pump affects the pressure of a fluid or gas by ____
REDUCING PRESSURE
RAISING PRESSURE
REGULATING PRESSURE
STABILIZING PRESSURE
Raising pressure
The bulb to a TXV has fallen off and the room is at 85F. The evaporation would ____
STARVE
FLOOD
INCREASE SUPERHEAT
RESPOND NORMALLY
Flood
A vertical 12” water pipe from the roof has a pressure gauge reading of 120 psi. How tall is the pipe?
277 FEET
1,440 INCHES
1,440 FEET
277 INCHES
277 feet
(Look up)
What is the disadvantage of having a low head pressure?
EVAPORATOR WOULD FLOOD
COMPRESSOR WOULD HUNT
EXPANSION VALVE WOULD NOT FEED PROPERLY
CONDENSER COULD NOT SUB-COOL
Expansion valve would not feed properly
If the suction pressure is 60 psig and the discharge is 180 psig, what would the compression ratio be?
5:1
3:1
2:6
4:1
3:1
A constant pressure expansion valve is being used instead of a thermostatic expansion valve under various loads will ____
STARVE THE EVAPORATOR
FLOOD THE EVAPORATOR
OPERATE BETTER THAN TEV
BOTH A AND B ARE CORRECT
Both A and B
(Fucker)
Which is not used as a cooling medium in a indirect system?
R-22
CALCIUM CHLORIDE
GLOCOL
SODIUM CHLORIDE
R-22
IN A REFRIGERATION PLANT, A SMALL INDUCTION REFRIGERATION MOTOR IS RUNNING ON AC CURRENT. IN ORDER FOR THE OPERATOR TO DETERMINE THE TRUE POWER CONSUMPTION, ASSUMING THAT IF EVERY ELIGIBLE CHARACTERISTICS HAVE BEEN MEANT, OF THE FOLLOWING THE POWER CONSUMPTION IS DETERMINED BY THE APPLICATION OF THE FORMULA:
WATTS = VOLTS X AMPS X OHMS
WATTS = VOLTS X AMPS X HERTZ
WATTS = VOLTS X AMPS
WATTS = VOLTS X AMPS X POWER FACTOR
Watts = Volts * Amps * power factor
An operator is running to centrifugal condenser 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 REDUCTION ON BOTH THE WATER FLOW RATE AND PRESSURE INTO THE CONDENSER
A REDUCTION IN TOTAL FLOW RATE TO CONDENSER
A REDUCTION IN WATER PRESSURE AT THE CONDENSER INLET
FOR THE PUMPS TO COMPENSATE TO MAINTAIN BOTH THE FLOW RATE AND DISCHARGE PRESSURE
A reduction to total flow rate to the condenser
A pressure relief valve that is installed on a reciprocating compressor that is using R-12 is normally set ____
ACCORDING TO DESIGN PRESSURE
ACCORDING TO OPERATING PRESSURE
LOWER THAN THE HIGH PRESSURE CUT OUT
AT LOW PRESSURE CUT OUT PLUS 50%
According to design pressure
Which refrigerant requires approval for use by the NUC fire department?
R-22
R-12
CARBON DIOXIDE
BUTANE
Butane
When installing a service valve to isolate a dual pressure device while keeping system in service, you would use a ____
TWO WAY VALVE
THREE WAY VALVE
PLUG VALVE
STOP VALVE
Three way valve
The solenoid unloaders on reciprocating compressors are designed to unload ____
ALL THE CYLINDERS
THE CLEARANCE SPACES IN THE CYLINDERS
CONTROL CAPACITY BY SHUTTING DOWN THE COMPRESSOR
CYLINDERS THAT CAN BE UNLOADED
The clearance spaces in the cylinders
The most common metering device used today in a reciprocating commercial refrigeration system over 3 tons is ____
AUTOMATIC EXPANSION VALVE
THERMOSTATIC EXPANSION VALVE
LOW SIDE FLOAT
HIGH SIDE FLOAT
Thermostatic expansion valve
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 ____
RAISE THE CONDENSER LIQUID LEVEL TO THE MAXIMUM
PRODUCE A LARGE AMOUNT OF LIQUID SUB-COOLING
RAISE THE CONDENSER HEAD PRESSURE
LOWER THE CONDENSER PRESSURE
Lower the condenser pressure
An RMO observes a gauge that reads the saturation pressure of a refrigerant. If chilled water is being circulated as the cooling medium, this reading can best be used to estimate the ____
CHILLED WATER TEMPERATURE RETURNING FROM THE BUILDING SPACES BEING COOLED
TEMPERATURE OF THE CHILLED WATER BEING PUMPED TO THE BUILDING SPACES THAT ARE BEING COOLED
PRESSURE OF CHILLED WATER BEING PUMPED TO THE BUILDING SPACES THAT ARE BEING COOLED
COOLING TOWER EFFICIENCY
Temperature of the chilled water being pumped to the building spaces that are being cooled
Why is a spring loaded PRV better to use than a fusible plug?
LESS EXPENSIVE
EASY AVAILABILITY
FUSIBLE PLUG CANNOT RESET
LARGER
Fusible plug cannot reset
Of the following, under what conditions of the heat in BTU/per min absorbed by the condenser water in a refrigerating plant is greater?
AT HIGHER EVAPORATIVE TEMPERATURE AND LOW CONDENSER TEMPERATURE
LOW EVAPORATIVE TEMPERATURE AND HIGH CONDENSER TEMPERATURE
HIGHER EVAPORATIVE TEMPERATURE AND HIGH CONDENSER TEMPERATURE
LOW EVAPORATIVE TEMPERATURE AND LOW CONDENSER TEMPERATURE
Low evaporative temperature and low condenser temperature
What would happen if the spring in the TEV broke?
FLOOD THE EVAPORATOR
STARVE THE EVAPORATOR
NO CHANGE
DAMAGE FEELER BULB
Flood the evaporator
What refrigeration systems are most likely to leak refrigerant in building spaces that are being cooled?
INDIRECT SYSTEMS
DIRECT SYSTEMS
INDIRECT CLOSED SYSTEMS
INDRIECT OPEN SYSTEMS
Direct systems
If you were running three compressors, which best describes the state of refrigerant leaving the third compressor?
MOSTLY LIQUID, SOME VAPOR
MOSTLY VAPOR, SOME LIQUID
SLIGHTLY SUPERHEATED VAPOR
HIGHLY SUPERHEATED VAPOR
Highly superheated vapor
Machine room safety standards have been established by ____
ARI-700
ARI-740
ASHRAE 34
ASHRAE 15
ASHRAE 15
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 ____
BALL
PLUG
GLOBE
GATE
Globe
What is the purpose of the equalizer line?
TO EQUALIZE PRESSURE IN THE TEV ALONG THE DIAPHRAM AND BELLOWS
TO MAKE UP FOR THE PRESSURE DROP IN EVAPORATOR
TO METER REFRIGERANT
TO REMOVE PRESSURE DROP
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?
COMPRESSOR WOULD OVERHEAT
COMPRESSOR WOULD OVERLOAD AND SHUT OFF
RMO WORKERS CAN RECEIVE ELECTRIC SHOCK IF THEY TOUCH IT
NOTHING
RMO workers can receive electrical shock if they touch it
R-11 and R-123 refrigerants are ____
OXYGEN DEPLETING
HEAVIER THAN AIR
ARE CLASS-1 AND CLASS-2 SUBSTANCES DEFINED BY EPA
ALL OF THE ABOVE
All of the above
(Dammit)
What is the TEV diaphragm made of
RUBBER
METAL
PLASTIC
GRAPHITE
Metal
In an emergency if you must dump refrigerant into the sewer, you will dump only when ____
SEWER IS NOT CONNECTED TO A STORM DRAIN
FIRST CONFIRM THAT REFRIGERANT IS NOT FLAMMABLE
FACILITY MANAGER APPROVES IT
YOU DISCHARGE UNDER THE SUPERVISION OF THE FIRE DEPT.
You discharge under the supervision of the fire department
An RMO notices a knocking reciprocating compressor. The RMO is assured the compressor has no worn parts. The most probable cause of the knocking is ____
INADEQUATE LUBRICATION
LIQUID SLUGGING
CRANKCASE PRESSURE TO LOW
SUCTION AND DISCHARGE NOT OPENING AND CLOSING
Liquid slugging
When installing a pipeline and you need to make a 90 degree elbow, which is the best way?
BEND PIPE
USE FACTORY MADE 90° ELBOW AND BRAZE
USE FLEXIBLE TUBING
USE TWO 45° ELBOWS
Use factory made 90 degree elbow and braze
1000 BTU’s are removed from 100 lbs of water at a temperature of 55F. What is the final water temperature?
55°F
50°F
45°F
40°F
45 F
(Yeah you know what to do)
An operator is using a portable recovery vessel and compressor to recover vapor refrigerant from a machine. The recovery process will slow down because ____
COMPRESSOR CAPACITY WILL DECREASE
VAPOR DENSITY WILL INCREASE
THE REFRIGERANT TEMPERATURE WILL INCREASE
THE REFRIGERANT PRESSURE WILL DECREASE
The refrigerant pressure will decrease
Due to a cold front there was a harsh drip in OAT, the most likely effect of this condition on the operation of the reciprocating machine would be that the thermostat causes the solenoid valve to ____
CLOSE, THE COMPRESSOR PUMPS DOWN AND SHUTS DOWN ON LOW PRESSURE
CLOSE AND THE COMPRESSOR WILL START ON HIGH PRESSURE
OPEN AND COMPRESSOR WILL PUMP DOWN AND GO OFF ON HIGH PRESSURE
OPEN AND COMPRESSOR WILL CONTINUE TO RUN AT REDUCED SPEED
Close, the compressor pumps down and shuts down on low pressure
As an RMO in charge you are requested to replace the gauge on the high side of the refrigeration system. The pressure graduation rate should be ____
1.2 OF DESIGN PRESSURE (AT LEAST)
THE RUPTURE GUARD HAS TO BE REPLACED ALSO
THE GAUGE HAS TO BE A COMPOUND GAUGE
THE GAUGE SHOULD BE GRADUATED TO PRESSURE
1.2 of design pressure (at least)
A jet ejector is used to raise oil mixed with the refrigerant which has collected at the bottom of the evaporator. If restricted ____
THE FLOW OF OIL WILL NOT BE EFFECTED
YOU WILL HAVE INSUFFICIENT HEAD TO LIFT THE OIL
THE TEMPERATURE OF THE REFRIGERANT EXITING THE JETS WILL DECREASE
THE OIL IN THE BOTTOM OF THE CHILLER WILL NOT LIFT IF IT BECOMES MIXED WITH LESS REFRIGERANT
You will have insufficient head to lift the oil
Assuming all conditions remain constant, the HP per ton of refrigerating effect would most likely ____
DECREASE AS THE SUCTION PRESSURE INCREASES
INCREASE AS AS THE SUCTION PRESSURE INCREASES
DECREASE AS THE DISCHARGE PRESSURE DECREASES
INCREASE AS THE DISCHARGE PRESSURE INCREASES
Decrease as the suction pressure increases
REFRIGERANTS ARE CHARACTERIZED BY THE PHYSICAL AND CHEMICAL PROPERTIES INCLUDING
LATENT HEAT, BOILING POINT, REFRIGERATION EFFECT AND OTHERS. OF THE REFRIGERANTS IN COMMERCIAL INDUSTRIES USED TODAY, THE ONE WITH THE HIGHEST LATENT HEAT AND REFRIGERATION EFFECT ____
R-12
CARBON DIOXIDE
AMMONIA
R-22
Ammonia
Low condensing pressure is not good because ____
LIQUID LEVEL IN CONDENSER WILL FALL TOO LOW
COMPRESSOR WILL WORK HARDER
EXPANSION VALVES WILL NOT FEED PROPERLY
HEAD PRESSURE WILL INCREASE
Expansion valves will not feed properly
Multistage centrifugal compressors each stage ____
TIP SPEED IS MORE WITH EACH STAGE
EVERY STAGE IS IDENTICAL
HANDLES MORE REFRIGERANT
HAS SMALLER VOLUME
Tip speed is more with each stage
Heat transfer rate in the condenser will ____
INCREASE WITH THE VELOCITY OF THE WATER IN THE TUBES
SHOW ONLY A SMALL INCREASE IF TUBES ARE DESCALED
INCREASE WITH A LOWER LEAVING WATER TEMPERATURE DIFFERENCE
SHOW THE LEAST BENEFIT FOR DESCALING THE TUBES AT HIGH WATER VELOCITIES
Increase with the velocity of the water in the tubes
A motor has 4 belts, the center belt is worn you would ____
CHANGE THE CENTER BELT
CHANGE CENTER BELT AND ALL OTHER BELTS
CHANGE THE OTHER BELTS
CHANGE TO DIRECT DRIVE SYSTEM
Change center and all other belts
Why should you charge with vapor?
YOU COULD BREAK THE RUPTURE GUARD WITH LIQUID
YOU CAN ENTRAIN THE OIL IN THE REFRIGERANT WITH LIQUID
YOU CAN FREEZE WATER IN THE TUBES WITH LIQUID
YOU CAN OVER CHARGE THE SYSTEM WITH LIQUID
You can freeze water in the tubes with liquid
An in-line refrigerant cleaning system is advisable because ____
NON-CONDENSEABLES CANNOT BE PROPERLY PURGED
REFRIGERANT REACTS WITH THE LUBRICATION OIL
REFRIGERANT SYSTEM IS HIGH PRESSURE
REFRIGERANT IS A TOXIC CLASS
Refrigerant reacts with the lubrication oil
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
INSPECTION SHOULD BE MADE FOR DIRTY TEV STRAINER
PARTIALLY CLOGGED DISCHARGE LINE
CHECK COMPRESSOR WIRING, FOR OVERLOADED EQUIPMENT
ADDITIONAL REFRIGERANT BE CHARGED
Additional refrigerant be charged
R-22 is ____
ODORLESS
ETHER LIKE ODER WHEN MIXED WITH AIR
EXPLOSIVE
BOILS AT A HIGHER TEMPERATURE THAN R-12
Odorless
An automatic purge unit is required for those refrigerating systems that have ____
DOUBLE INDIRECT OPEN SPACE SYSTEMS
SYSTEMS OPERATING BELOW ATMOSPHERIC PRESSURE
ABSORPTION COMPRESSORS
OUTSIDE AIR DAMPERS
Systems operating below atmospheric pressure
The most correct way to describe a braised joint is ____
PRESSURE FITTING
GAS TIGHT FITTING
START TO MELT AT 400°F
START TO MELT AT 500°F
Gas tight fitting
YOU ARE AN MO 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 ____
RE-ADJUST THE TEV SUPERHEAT SETTING
DEACTIVATE THE FREEZE STAT
RAISE THE COMPRESSOR DISCHARGE OPERATING PRESSURE
LOWER THE COMPRESSOR SUCTION OPERATING PRESSURE
Lower the compressor suction operating pressure
What is the purpose of having a service valve stem cap?
TO PROTECT FROM BEING INADVERTENTLY TURNED FROM ITS POSITION AND FROM BEING DAMAGED
TO LET YOU KNOW THE POSITION OF THE VALVE
TO LET YOU NOTICE VALVE FROM A DISTANCE
TO CAP OFF VALVE SO THAT UT CAN NEVER BE USED
To protect from being inadvertently turned from its position and being damaged
One disadvantage of using bribes as a cooling medium is corrosion.in commercial practice, corrosion and rust is reduced by the addition of ____ to the brine solution
WEAK ACID SOLUTION
ZINC COMPOUNDS
GLYCOLS
DI-CHROMATES
Di-chromates
If you just purchased a thermometer and need to check if it’s working properly, how would you do it?
TOUCH IT IN A POT OF BOILING WATER
TOUCH IT TO BUCKET OF ICE / ICE WATER
COMPARE TO 2 OTHER THERMOMETERS
COMPARE TO ANOTHER RMO THERMOMETER
Touch it to a bucket of ice/ice water
A bimetal disk or klixon is used to ____
STOP THE REFRIGERATION EQUIPMENT BEFORE EXCESSIVE PRESSURE OCCUR
STOP THE REFRIGERATION EQUIPMENT AT A PREDETERMINED MINIMUM OPERATING PRESSURE
PROTECT THE WIRING AND COMPONENTS AGAINST EXCESSIVE CURRENT DRAW
PROTECT THE COMPRESSOR AGAINST THE LOSS OF OIL PRESSURE
Protect the wiring and components against excessive current draw
Of the following the most undesirable property in refrigerant is ____
LOW CORRESPONDING COMPRESSOR DISCHARGE TEMP
LOW VISCOSITY
LOW LATENT HEAT
LOW CORRESPONDING OPERATING PRESSURE
Low latent heat
If you are using a portable compressor unit to remove vapor. What would happen when you are recovering?
COMPRESSOR SPEED IS DECREASED
VAPOR DENSITY IS DECREASED
REFRIGERANT TEMPERATURE WILL DROP
COMPRESSOR EFFICIENCY WILL DECREASE
Vapor density is decreased
ASSUME AN OPERATOR IS ABLE TO OBSERVE R-11, WATER AND LUBRICATING OIL TOGETHER AT 70°F. UNDER THESE CONDITIONS, THE WATER, MOISTURE, AND FLUIDS WOULD SETTLE IN THE CONTAINER FROM TOP TO BOTTOM IN WHAT ORDER?
WATER, OIL, REFRIGERANT
OIL, REFRIGERANT, WATER
REFRIGERANT, OIL, WATER
OIL, WATER, REFRIGERANT
REFRIGERANT, OIL, WATER
