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RMO Exam

Question 1 of 89

1

Because of the latent heat load, refrigeration machine operator was instructed to start the reciprocating plant for air conditioning. Of the following according to recommended practice, the first thing to do is:

Select one of the following:

  • Turn on chilled water pumps and open the bypass to lighten the load

  • Install larger fuse to take the initial load and then turn on the cooling tower fans

  • Turn on chilled water pump, condenser water pumps and cooling tower fans

  • Set thermostat a few degrees higher

Explanation

Question 2 of 89

1

The most important reason to use 2 compressors in a cascade system is to :

Select one of the following:

  • Accomplish lower temperature

  • Permit the use of inexpensive lubrication oil

  • Avoid the need for very high compression ratios

  • Divide the cooling load between 2 compressors

Explanation

Question 3 of 89

1

The advantage of forced draft over natural draft cooling tower is

Select one of the following:

  • The possibility of lower water out temp

  • There is no dependence on natural wind velocity

  • Use of a smaller tower size

  • All of the Above

Explanation

Question 4 of 89

1

what is 29.92" HG in Kpa

Select one of the following:

  • 101.3

  • 101.28

  • 101.26

  • 103.2

Explanation

Question 5 of 89

1

The rupture disk is always piped into the

Select one of the following:

  • High side

  • Low side

  • Either side of the system

  • Neither side of the system

Explanation

Question 6 of 89

1

A fusible plug melts at

Select one of the following:

  • 450 F

  • 280 F

  • 212 F

  • 800 F

Explanation

Question 7 of 89

1

When will the BTUs absorbed by the condensing water be the greatest?

Select one of the following:

  • Low cond temp, low cond water temp

  • High cond temp, High cond water temp

  • High Cond temp, Low Cond water temp

  • Low Cond temp, High Cond water temp

Explanation

Question 8 of 89

1

Flooded Evaporators have high heat transfer per square foot, What may be a disadvantage?

Select one of the following:

  • Requires a smaller charge

  • Requires a larger charge

  • Requires the use of a TXV for proper feed

  • Water has to be drained daily

Explanation

Question 9 of 89

1

Shell and tube condensers have the advantage of

Select one of the following:

  • Removing heads for cleaning the water sides of the tubes

  • The refrigerant connections do not have to be disrupted

  • Using acid for cleaning

  • Both A and B are correct

Explanation

Question 10 of 89

1

Shell and coil condensers have the advantage of

Select one of the following:

  • Removing the heads for cleaning the water sides of the tubes

  • The refrigerant connections do not have to be disrupted

  • Has less of a chance of developing leaks

  • Both A and B are correct

Explanation

Question 11 of 89

1

How many BTUs would be removed in a 30 ton system?

Select one of the following:

  • 12,000 per hour

  • 360,000 per minute

  • 12,000 per minute

  • 360,000 per hour

Explanation

Question 12 of 89

1

If you have 62 psi at 35 F and 70 psi at 45 deg F, what would 38 deg F be?

Select one of the following:

  • 66

  • 64.4

  • 65

  • 62

Explanation

Question 13 of 89

1

Copper is used in refrigeration systems, like in heat ex-changers because?

Select one of the following:

  • Easy fabrication

  • Easy durability

  • High thermal conductivity

  • Flexability

Explanation

Question 14 of 89

1

The accessories on the liquid line are in what order?

Select one of the following:

  • solenoid valve, drier, and sightglass

  • receiver, drier, solenoid valve, and sightglass

  • muffler, drier, sightglass, and solenoid valve

  • accumulator, muffler, drier, sightglass

Explanation

Question 15 of 89

1

A condenser is 20' long and 6' in diameter, what is the volume in gallons if 7.48 gallons is 1 cu/ft?

Select one of the following:

  • 565

  • 4227

  • 1808

  • 1205

Explanation

Question 16 of 89

1

If the low pressure cutout cycles the compressor off, what starts the compressor again?

Select one of the following:

  • Solenoid valve

  • High pressure cut out

  • Low pressure cut out

  • Thermostat

Explanation

Question 17 of 89

1

Removing insulation on the suction line with the engine room temp at 85F, what will occur?

Select one of the following:

  • Flooded evaporator

  • Starved evaporator

  • Excessive superheat

  • Low superheat

Explanation

Question 18 of 89

1

If you were running three compressors, which best describes the state of refrigerant leaving the third evaporator coil?

Select one of the following:

  • Mostly liquid, some vapor

  • Mostly vapor, some liquid

  • Superheated vapor

  • Highly superheated vapor

Explanation

Question 19 of 89

1

An electric motor that is rated at 3 HP will?

Select one of the following:

  • Use three phase

  • Need a capacitor

  • Use a single Phase

  • Will run with reduced power output

Explanation

Question 20 of 89

1

In a 3 stage centrifugal chiller, what happens to the pressure as it reaches the final stage?

Select one of the following:

  • Increases

  • Decreases

  • Speed changes not pressure

  • Volume changes not the pressure

Explanation

Question 21 of 89

1

With an induced draft cooling tower, what is the lowest temperature attainable for a cooling tower?

Select one of the following:

  • Wet bulb equal to dry bulb

  • Dry bulb slightly lower than wet bulb

  • Dry bulb higher than wet bulb

  • Wet bulb can never be lower than dry bulb

Explanation

Question 22 of 89

1

When a compressor is running fine at full flow and you throttle down flow causing the compressor to stop running normal (short cycle), why would this happen?

Select one of the following:

  • Dirty filter/ strainer

  • Air getting in seals

  • Low pressure cut out

  • High head pressure

Explanation

Question 23 of 89

1

When dry bulb is 75F and wet bulb is 75F?

Select one of the following:

  • Not possible

  • Very low humidity

  • Thermometer is defective

  • 100% relative humidity

Explanation

Question 24 of 89

1

When a compressor is said to have a safety head this means :

Select one of the following:

  • Compressor operates with normal pressures

  • Compressor operates with low pressures

  • Compressor has a pressure relief device

  • Compressor has high pressure cut out

Explanation

Question 25 of 89

1

The cylinder unloader controls capacity, is there any other function it may have?

Select one of the following:

  • Assist with compressor shut down

  • Assist with compressor start up

  • There is no other function

  • Releases pressure for protection

Explanation

Question 26 of 89

1

An operator suspects that shorted motor windings have caused the motor overloads to trip. In order to investigate this condition, the operator would be most correct to use :

Select one of the following:

  • Capacitor

  • Voltmeter

  • Ohmeter

  • Ammeter

Explanation

Question 27 of 89

1

When recovering R22, What color would the cylinder be that you are storing the refrigerant in?

Select one of the following:

  • Yellow tops

  • White tops

  • Green tops

  • Gray tops

Explanation

Question 28 of 89

1

If unloaders were to fail in the unloaded position, what happens in a system using reciprocating compressor?

Select one of the following:

  • The evaporator will starve

  • Cause high superheat

  • Not enough refrigerant to coil

  • All of the above

Explanation

Question 29 of 89

1

When the temperature and the load increase and you need to add another pump online, you would :

Select one of the following:

  • Close both suction and discharge

  • Open both suction and discharge

  • Open suction and throttle discharge

  • Open discharge bypass and close suction

Explanation

Question 30 of 89

1

When a system does not have unloaders, what is needed?

Select one of the following:

  • Other capacity control

  • Variable inlet guide vanes

  • An economizer

  • Solenoid on liquid line

Explanation

Question 31 of 89

1

When an evaporator is not equipped with an equalizer line, you would most likely find

Select one of the following:

  • Feeder bulb placed in different area

  • A distributor

  • An automatic expansion valve

  • Both high and low side pressures identical

Explanation

Question 32 of 89

1

When you plan on overhauling a system and you have recovered all liquid refrigerant, what is next?

Select one of the following:

  • Go ahead and do the work

  • Recover all vapor, then do the work

  • Send liquid nitrogen through

  • Evacuate system

Explanation

Question 33 of 89

1

When there is a 5lb pressure drop across evaporator, you need an external equalizing line, what happens if it disconnects?

Select one of the following:

  • Excessive superheat

  • Evaporator would starve

  • Evaporator would flood

  • TEV would not function

Explanation

Question 34 of 89

1

The metering device used in a condenser is a high side float, this device will :

Select one of the following:

  • Control the amount of water in condenser

  • Control the amount of refrigerant in condenser

  • Keeps a constant pressure

  • Keeps a constant temperature

Explanation

Question 35 of 89

1

If a low side float is being used :

Select one of the following:

  • Pressure will be constant

  • It will control refrigerant flow

  • It will control water flow

  • Temperature is constant

Explanation

Question 36 of 89

1

The heat that boils off in a condenser is :

Select one of the following:

  • Latent heat

  • Sensible heat

  • Superheat

  • All of the above

Explanation

Question 37 of 89

1

The condenser that uses air and water for cooling is the :

Select one of the following:

  • Air cooled

  • Water cooled

  • Evaporative

  • Both a and b are correct

Explanation

Question 38 of 89

1

A hermetic compressor is operating with a low refrigerant charge, What is the most likely effect this condition would have on the compressor?

Select one of the following:

  • Head pressure would rise

  • Compressor would operate at higher temperature

  • Have no effect on the compressor

  • Oil pressure would rise

Explanation

Question 39 of 89

1

A centrifugal chiller has a suction pressure of 18" Hg vacuum and discharge pressure of 6 psig. What is the compression ratio of this unit ?

Select one of the following:

  • 3.50

  • 2.96

  • 1.75

  • 2.76

Explanation

Question 40 of 89

1

If you had to install a solenoid valve to a system which uses 110 volts and needed to convert it to 24 volts, what would you use?

Select one of the following:

  • Step up transformer

  • Step down transformer

  • AC to DC rectifier

  • Rewire circuit with smaller gauge wire

Explanation

Question 41 of 89

1

If you had 38 degrees in the evaporator, what should you suction pressure be for R22?

Select one of the following:

  • 66 Psia

  • 66 Psig

  • 76 Psig

  • 76 Psia

Explanation

Question 42 of 89

1

An oil with low viscosity would :

Select one of the following:

  • Not be used for refrigeration

  • Be used for engine/motors

  • Be used for air conditioning

  • Both B and C are correct

Explanation

Question 43 of 89

1

When charging a centrifugal system the position of the valve is :

Select one of the following:

  • Front seated

  • Back seated

  • Cracked off the back seat

  • Closed

Explanation

Question 44 of 89

1

The suction and discharge valves in a reciprocating compressor are positioned :

Select one of the following:

  • Over valve plate

  • Under valve plate

  • Both under and over valve plate

  • None of the above

Explanation

Question 45 of 89

1

What refrigerants are you not able to dump?

Select one of the following:

  • CFC

  • HCFC

  • HFC

  • Any refrigerant containing chlorine or flourine

Explanation

Question 46 of 89

1

There is an automatic water regulating valve on a reciprocating chiller. Water is entering the condenser at 85F and leaving the condenser at 88F. You know there is no scale and the tubes are not covered with film. What can be causing this condition?

Select one of the following:

  • High head pressure

  • Low suction pressure

  • Water valve stuck open

  • Water valve stuck closed

Explanation

Question 47 of 89

1

How low can chiller water temperature be?

Select one of the following:

  • 32 degrees F

  • 33 degrees F

  • 38 degrees F

  • 42 degrees F

Explanation

Question 48 of 89

1

While using a halide torch to check for refrigerant leaks, if the flame was to turn yellow, what happened?

Select one of the following:

  • Container is empty

  • Restriction in tube

  • Refrigerant is leaking

  • Refrigerant has high moisture content

Explanation

Question 49 of 89

1

What is the cubic feet of a 20' long 6' vessel on the evaporator?

Select one of the following:

  • 120 cubic feet

  • 565 cubic feet

  • 4,235 cubic feet

  • 4,710 cubic feet

Explanation

Question 50 of 89

1

A water regulating valve is installed in a water cooled condenser. The operating force on this valve is respondent to :

Select one of the following:

  • High side pressure

  • Chilled water temperature

  • Circulating water pressure through the condenser

  • Manual operation

Explanation

Question 51 of 89

1

Compound gauges can measure:

Select one of the following:

  • Above atmospheric

  • Below atmospheric

  • Temperature

  • All of the above

Explanation

Question 52 of 89

1

A low pressure refrigeration system has a pin hole in the evaporator. What is the most likely result?

Select one of the following:

  • High head pressure

  • Frost around leak area

  • High condenser water pressure

  • Low condenser water pressure

Explanation

Question 53 of 89

1

What does the centrifugal compressor generate inside?

Select one of the following:

  • High pressure, low velocity

  • High volume, low pressure

  • Low velocity, Low pressure

  • High velocity, high pressure

Explanation

Question 54 of 89

1

Oil flashpoint temperature in the compressor should be :

Select one of the following:

  • Lower than the heat of compression

  • Higher than the heat of compression

  • Equal to the heat of compression

  • Equal to the heat absorbed

Explanation

Question 55 of 89

1

Compressor motors that operate inside the refrigerant atmosphere (atmospheric) :

Select one of the following:

  • Must use materials compatible with the system refrigerants

  • Motors must be assembled in clean atmosphere and kept dry

  • Are not worked on in the field

  • All of the above

Explanation

Question 56 of 89

1

In a centrifugal three stage compressor:

Select one of the following:

  • Pressure increases with each stage

  • Impellers are same size

  • Impellers increase with each stage

  • Both A and B are correct

Explanation

Question 57 of 89

1

An operator suspects that a vertical check valve on a discharge of a centrifugal pump is defective, this is a condenser pump and one of three pumps in parallel. If the suspicion is true and the check valve fails to seat when required, the pump and connecting piping will most likely be damaged when :

Select one of the following:

  • Lubricating the pump

  • After having bled air from the pump casing petcock

  • Starting an additional pump

  • Shutting the pump down

Explanation

Question 58 of 89

1

In relation to the suction pressure of a compressor, The reading in the oil pressure gauge should read :

Select one of the following:

  • 15-30 psi lower

  • 60-90 psi higher

  • 15-30 psi higher

  • 30-60 psi lower

Explanation

Question 59 of 89

1

The following most accurate statement regarding compressor motors that run in a refrigerant atmosphere is that they :

Select one of the following:

  • May use internal rubber cushions

  • May be repaired on site when they malfunction

  • Use materials tailored to the refigerant

  • Use same materials as a pump in air

Explanation

Question 60 of 89

1

The following is an example of an "inline" refrigerant cleaning system which may be used with a centrifugal compressor containing R123 refrigerant is :

Select one of the following:

  • Refrigerant recovery

  • Refrigerant disposal

  • Refrigerant reclaiming

  • Refrigerant recycling

Explanation

Question 61 of 89

1

Regarding fire safety ANSI/ASHRAE, which classification indicates the latest flammability and least toxicity?

Select one of the following:

  • A1

  • B2

  • A2

  • B1

Explanation

Question 62 of 89

1

Bubbles in the sight glass are most likely caused by :

Select one of the following:

  • An overcharged system

  • Non-condensable gases

  • Light load on the plant

  • Partially plugged filter/drier

Explanation

Question 63 of 89

1

In addition to regulating the refrigerant flow according to the needs of the system, metering devices also serve to :

Select one of the following:

  • Increase compressor capacity

  • Hold system to a constant load

  • Restrict flow of refrigerant from the high side to low side

  • Shed load as load increases

Explanation

Question 64 of 89

1

Regardless of safety classification of the refrigerant in use, in the event of refrigerant escape, the RMO should be aware of :

Select one of the following:

  • A refrigerant fire

  • Refrigerant poisioning

  • Oxygen deprivation

  • Atmospheric superheating

Explanation

Question 65 of 89

1

The refrigeration unit which you have been assigned to is being taken out of service for major repairs. You have been assigned to withdraw refrigerant for storage in suitable containers. According to the NYC fire law handbook you must ensure that containers :

Select one of the following:

  • Are approved by the US department of transportation

  • Are approved by the facilities manager

  • Do not weigh more than 200lbs when filled

  • Do not exceed 55 gallon capacity

Explanation

Question 66 of 89

1

An operator confirms that a chiller water pump in a refrigeration system employing R123 is cavitating, of the following, the most likely cause for this condition is :

Select one of the following:

  • Malfunctioning of the water makeup float valve

  • Too much time in between pump servicing

  • Operating at sustained high loads

  • Lowering the chilled water temperature

Explanation

Question 67 of 89

1

An RMO is logging readings from a reciprocating compressor-refrigerating unit. The crankcase and compressor discharge temp have dropped significantly and suction line pressure is high. Of the following the one that may cause this set of conditions is:

Select one of the following:

  • Compressor cycling

  • An expansion valve which is closed too much

  • An expansion valve which is open too wide

  • Faulty compressor valves

Explanation

Question 68 of 89

1

The Ratio of actual pressure of water vapor in the atmosphere to the saturation pressure / temp is called :

Select one of the following:

  • Absolute humidity

  • Humidity effect

  • Partial pressue

  • Relative humidity

Explanation

Question 69 of 89

1

The dividing line between the high and low sides of the refrigeration system is :

Select one of the following:

  • The connection between the compressor and condenser

  • Needle valve mechanism

  • Compressor outlet and the orifice of the metering device

  • Center plate of the refrigeration mechanism

Explanation

Question 70 of 89

1

An RMO verifies that a condenser water pump is cavitating in a refrigeration system employing R22 refrigerant. Of the following the most likely cause for this condition is:

Select one of the following:

  • Air leaks through the pump packing

  • Operating at sustained high loads

  • Faulty cooling tower water level controller

  • Too long a period between pump servicing

Explanation

Question 71 of 89

1

An operator notices that a centrifugal pump operates satisfactorily when delivering at full discharge, but loses water flow if throttled. The operator would most accurately assume that this condition is due to:

Select one of the following:

  • Water hammer

  • Clogged strainer in pump inlet

  • Poor bearing lubrication

  • Air leaks in the pump

Explanation

Question 72 of 89

1

Assuming that a refrigeration plant uses a horizontal shell and tube condenser with the water in the tubes and the refrigerant in the shell. In controlling the operation of the condenser, the operator should take into account that most likely the heat transfer rate BTU/per sq ft per second in the condenser will :

Select one of the following:

  • Show the least benefit for descaling tubes at high water velocity

  • Increase with the velocity of water in the tubes

  • Increase with lower log mean temperature difference

  • Show only a small increase if the tubes are descaled

Explanation

Question 73 of 89

1

Electric devices may be used to provide built in defrosting of refrigeration machine evaporator units. These devices are classified as:

Select one of the following:

  • Relays

  • Induction coils

  • Capacitors

  • Resistors

Explanation

Question 74 of 89

1

Latent heat and refrigeration effect are usually listed as refrigerant properties. The refrigerating effect is also always a lower value than the latent heat because the :

Select one of the following:

  • Heat required to cool the refrigerant from compressor discharge to evaporative temp is subtracted from the latent heat

  • Refrigerant latent heat is divided by specific gravity of the refrigerant

  • Refrigerant critical temperature is factored into the calculation of the refrigerating effect

  • Refrigerant latent heat is divided by the refrigerant circulation rate

Explanation

Question 75 of 89

1

Superheated vapor flowing into a reciprocating compressor protects the compressor parts against liquid intake. Of the following, one of the problems associated with superheat is that:

Select one of the following:

  • Non-condensables are more prone to collect in the system

  • Frost may develop in the suction line

  • It will decrease the capacity of the compressor and the refrigeration machine

  • The compressor head pressure drops too low

Explanation

Question 76 of 89

1

An operator observes a reading of 60c on a refrigerating unit. The same reading in F scale would be closer to: (x1.8+32)

Select one of the following:

  • 140

  • 185

  • 155

  • 170

Explanation

Question 77 of 89

1

What is the state of refrigerant as it leaves the compressor and as it leaves the condenser:

Select one of the following:

  • Superheated vapor and superheated liquid

  • Superheated vapor and warm subcooled liquid

  • Saturated Vapor and cold sub cooled liquid

  • Saturated vapor and warm sub cooled liquid

Explanation

Question 78 of 89

1

Clearance volume:

Select one of the following:

  • Affects compressor capacity

  • Is the space that traps liquid refrigerant

  • Varies, depending on compressor speed

  • Is the same on all compressors

Explanation

Question 79 of 89

1

A Thermal is attached to the suction pipe between the evaporator coil and the compressor covered by an insulating line. Assuming the machine room is 85F unraveling of the insulation would result in:

Select one of the following:

  • Adequate superheat

  • Starved evaporator

  • Excessive superheat

  • Flooded Evaporator

Explanation

Question 80 of 89

1

Of the following one of the primary reasons for the insulation of a crankcase breather line is :

Select one of the following:

  • Increase the compressor efficency

  • To prevent oil slugging in the compressor

  • Keep the shaft packing lubricated

  • To prevent refrigerant from entering the compressor suction

Explanation

Question 81 of 89

1

A RMO notices excessive cycling of the temp control for a reciprocating compressor refrigeration unit. The crankcase temp is high, the compressor discharge temp is low and the suction line is high, of the following the one that may be causing this set of conditions is:

Select one of the following:

  • Purge unit operation

  • An expansion valve that is open too wide

  • Faulty compressor valves

  • Condenser operation, dirty tubes, or cooling water control

Explanation

Question 82 of 89

1

A reciprocating system using an evaporative condenser, the muffler is installed between:

Select one of the following:

  • Evaporator and Compressor

  • Receiver and expansion valve

  • Compressor and evaporative condenser

  • Receiver and condenser

Explanation

Question 83 of 89

1

While operating an R12 reciprocating system, the RMO noticed the oil foaming the in the crankcase. This condition most likely would have been caused by:

Select one of the following:

  • Addition of liquid freon

  • Sudden drop in oil Temp

  • Sudden drop in crankcase pressure

  • Addition of oil to the crankcase

Explanation

Question 84 of 89

1

Assume that a new valve plate has been installed while they are repairing a reciprocating compressor in a refrigeration plant. The installation of a new valve plate will require the replacement of:

Select one of the following:

  • All valve plates, springs and some valve seats

  • All valve and valve seats

  • Valve seats only

  • Suction Valves only

Explanation

Question 85 of 89

1

During a hot weekend, RMO is instructed to start additional reciprocating machine. The sequence of actions on startup would most likely be:

Select one of the following:

  • check compressor oil, start cooling towers, check valves are in correct position, turn on machine, start chiller and condenser water pumps

  • start chiller and condenser water pumps, start cooling water tower fans, check compressor oil levels, check that valves are in correct position, turn machine on

  • turn machine on, check valves are in correct position, start tower fans, check compressor oil levels, start chiller and condenser water pumps

  • check valves are in correct position, start cooling water tower fans, start machine, start chiller and condenser water pumps, check compressor oil levels

Explanation

Question 86 of 89

1

While doing a routine inspection, the RMO noticed the bulb of the TEV on the floor, the operator should attach the bulb at:

Select one of the following:

  • center of the coil

  • expansion valve outlet

  • end of coil

  • 3/4 away towards the end of the coil

Explanation

Question 87 of 89

1

When operating a reciprocating refrigeration system with a belt driven compressor, an RMO notices that one of the 4 belts is broken. Of the following, the most advisable course of action for the RMO would be to:

Select one of the following:

  • Put more grease on the remaining belts

  • Replace all 4 belts with a new set

  • Replace the broken belt only

  • Operate with the remaining 3 belts

Explanation

Question 88 of 89

1

An operator reads the valve tag on a pressure relief valve and notices that the valve is set to unseat at an evaporator pressure of 15 psi, The corresponding set pressure in inches of HG is :

Select one of the following:

  • 18

  • 14

  • 20

  • 30.3

Explanation

Question 89 of 89

1

What is the maximum percentage that a refrigerant can be stored in a cylinder?

Select one of the following:

  • 75%

  • 80%

  • 90%

  • 100%

Explanation

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