Refrigerant Machine Operator Certification Practice Test #1 Flashcards by Christine Banker

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

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Unloaders are used to

INCREASE CAPACITY

STOP FLOW OF REFRIGERANT WITHOUT STOPPING

REDUCE CAPACITY

START FLOW OF REFRIGERANT THROUGH SYSTEM

Reduce capacity

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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

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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

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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

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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

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Which of the following ASHRAE safety groups is the most dangerous

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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)

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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

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

Refrigerant Machine Operator Certification Practice Test #1 Flashcards

(100 cards)