Chap. 117, 118, 119, 120, 121, 122,123 & 124 Flashcards by Ivan Arizaga

The two types of evaporators, dry evaporators and flooded evaporators differ principally in what respect?

a) the dry evaporator cannot cool liquids
b) method of refrigerant circulation
c) type of refrigerant used
d) size of the evaporator
e) field maintenance availability of the types

b) method of refrigerant circulation

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An evaporator that contains only a small amount of liquid refrigerant at any time is what type of evaporator?

a) Dry evaporator
b) Flooded evaporator
c) Wet evaporator
d) All of the above
e) None of the above

a) Dry evaporator

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Refrigerant evaporators:

a) are only used in ammonia systems
b) are part of the high side of the system
c) are used to transfer oil
d) are only used with very high pressure refrigeration systems
e) are used to transfer heat

e) are used to transfer heat

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The evaporator which increases heat exchange by crimping thin metal plates to its form is which type of evaporator?

a) Plate surface
b) Bare tube
c) Shell and tube
d) Finned tube
e) none of the above

d) Finned tube

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An evaporator which can easily be cleaned and defrosted manually without interrupting the cooling process is which type of evaporator?

a) Bare finned
b) Finned
c) Plate surface
d) Shell and tube
e) None of the above

c) Plate surface

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Which of the following statements about the shell and tube evaporator type is false?
a) It is also known as a chiller.
b) This type of evaporator cools mainly liquids.
c) The refrigerant is circulating in the shell in the
flooded operation.
d) Refrigerant vapour is drawn out of the evaporator by the compressor.
e) The liquid to be cooled circulates through the tubes in the direct-expansion operation

e) The liquid to be cooled circulates through the tubes in the direct-expansion operation

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Air-cooled condensers of large capacity are found mainly in which of the following locations?

a) roof tops
b) closed rooms with low air circulation
c) warm dry rooms
d) cold rooms with low air circulation
e) any of the above

a) roof tops

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Which of the following statements about double tube
condensers is true?
a) It consists of two separate tubes side by side.
b) It cannot be used with air cooled condensers.
c) Water flow in the inner tube is in the opposite direction of the flow of refrigerant.
d) It has the highest efficiency of the water-cooled
condensers.
e) It is a small condenser for a large capacity system

c) Water flow in the inner tube is in the opposite direction of the flow of refrigerant

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The condenser which is very expensive to clean and requires the tubes to be cleaned with acid and neutralized is the:

a) shell and tube condenser
b) shell and coil condenser
c) double tube condenser
d) evaporative condensers
e) baffle condensers

b) shell and coil condenser

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The amount of water used in an evaporative condenser is only a small percentage of that used in a water condenser of the same capacity. This is due primarily to what?
a) Evaporating condensers also use air to cool the
refrigerant.
b) The evaporating condensers spray refrigerated water onto condensing coil.
c) Water evaporating requires a large amount of latent heat.
d) Water being recirculated.
e) None of the above

c) Water evaporating requires a large amount of latent heat.

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The common types of water-cooled condensers used in refrigeration systems are:

the shell and tube
the shell and coil
the double tube
the plate surface
a) 1, 2, 3
b) 1, 3, 4
c) 2, 3, 4
d) 1, 2, 4
e) 3, 4

a) 1, 2, 3

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Defective condenser operation is a result of the presence of all of the following except

a) scale forming chemicals
b) dirty cooling water
c) noncondensible gases
d) low coolant circulation
e) compressor lubricating oil

e) compressor lubricating oil

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The purpose of a condenser in a refrigeration system is:

a) to remove the sensible heat from the refrigerant
b) to remove the latent heat from the refrigerant
c) to cool the liquid refrigerant
d) to vaporize the liquid refrigerant
e) to reduce the pressure in the evaporator

b) to remove the latent heat from the refrigerant

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Starting, stopping or unloading of the compressor is usually done by all of the following operating controls except:
a) temperature actuated control
b) viscosity activated control
c) pressure activated control
d) humidity activated control
e) All of the above can control the starting, stopping or
unloading of the compressor

b) viscosity activated control

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The operating control which uses a bimetal element is a:

a) fluid expansion actuating control
b) pressure actuated control
c) humidity actuated control
d) temperature actuated control
e) solenoid actuated control

d) temperature actuated control

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Which of the following statements about pressure stats is false?
a) The control is connected to the suction line of the
compressor.
b) The control consists of a switch actuated through a
linkage arrangement connected to a bellows or diaphragm.
c) A pressure-stat can be used in conjunction with an
automatic expansion valve.
d) When the pressure drops to the minimum allowable the
switch acts opposite to a thermostat and opens.
e) A pressure-stat cannot be used with a capillary tube

c) A pressure-stat can be used in conjunction with an

automatic expansion valve

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The operating control which consists of a hygroscopic element made of material similar to multiple strands of human hair is called a:

a) humidistat
b) thermostat
c) fluid expansion regulator
d) pressure-stat
e) bimetal element

a) humidistat

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Which of the following actuating control valves is
electromagnetically operated?
a) Thermostat valve
b) Fluid expansion regulator valve
c) Evaporator pressure regulating valve
d) Condenser cooling water regulating valve
e) Solenoid valve

e) Solenoid valve

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In many cases evaporator pressure must not be allowed to drop below a certain level to prevent which of the following results?

a) frosting of coils
b) evaporator valve lock
c) tubing implosion
d) overheating of the evaporator
e) overheating of the compressor

a) frosting of coils

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Safety controls serve what function?

a) They stop operation if the temperature gets too high.
b) They stop operation when the pressure gets too high.
c) They stop operation when the pressure is too low.
d) They stop operation when the temperature is too low.
e) All of the above

e) All of the above

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Which of the following statements about flow switches is false?
a) They are used on chilled water.
b) They are used as lockout switches when flow is
insufficient.
c) They are operated by the force exerted on a flexible vane
immersed in the liquid flowing in the line.
d) They can only be used to regulate liquid flow (i.e. not air flow).
e) They can be used to close flow indicator circuits

d) They can only be used to regulate liquid flow (i.e. not air flow)

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The safety control which uses a current transformer with a resistor in the motor circuit is known as

a) high motor temperature cutup
b) low oil sump temperature protection
c) motor overload protection
d) solenoid valve
e) high oil temperature cutout

c) motor overload protection

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Oil pressure failure switches are used to perform which of the following functions?
a) Keep oil from freezing at low pressure.
b) Prevent compressor startup if the oil heater fails.
c) Separate refrigerant dissolved in the oil from the
lubricant.
d) Shut down the compressor when the oil pressure drops below the minimum.
e) Keep the oil pressure at a level where the oil will
not freeze

d) Shut down the compressor when the oil pressure drops below the minimum.

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The most widely used refrigerant control which consists of a bellows or a diaphragm chamber connected to a temperature sensing bulb by means of a small capillary tube is a/an

a) thermostatic expansion valve
b) automatic expansion valve
c) low pressure float valve
d) hand operated expansion valve
e) high pressure float valve

a) thermostatic expansion valve

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Which of the statements about automatic expansion valves is false? a) The valve maintains constant pressure in the evaporator during compressor operation regardless of the load. b) When the compressor stops the valve automatically shuts off. c) A spring exerting a downward force on the diaphragm tends to open the valve. d) The spring force is countered by evaporator pressure acting downward against the diaphragm which closes the valve. e) The control may be used with multiple cooling coils connected to the same compressor

e) The control may be used with multiple cooling coils | connected to the same compressor

Which control is used to maintain a constant level of liquid refrigerant in a flooded evaporator in the liquid reserve tank? a) thermostatic expansion valve b) automatic expansion valve c) low pressure float valve d) hand operated expansion valve e) high pressure float valve

c) low pressure float valve

The simple control which restricts the flow of liquid from the condenser to the evaporator and maintains a pressure difference between the two units by using a considerable pressure drop resulting from resistance between the devices length and small bore is called a) a high pressure float valve b) a low pressure float valve c) a bypass line d) a capillary tube e) an external float chamber

d) a capillary tube

In a system controlled by a high pressure float valve insufficient liquid will cause which of the following results? a) automatic system shut down b) boosting the compressors pressure c) liquid being carried over to the compressor with the vapour d) starving the evaporator and reducing the capacity of the system e) all of the above

d) starving the evaporator and reducing the capacity of the system

One method of controlling the capacity of reciprocatingcompressors is to bypass the discharge from one or morecylinders back to the suction side of the compressor. The control is called a) compressor unloading b) dampering c) suction throttling d) cylinder bypass e) sectional evaporating

d) cylinder bypass

Sectional evaporators control the capacity of the evaporator by which of the following means? a) Varying the quantity of air being cooled passing over the evaporator coils. b) Intermittent operation of the compressor. c) Divided multipart evaporators which have refrigerant control valves which can be shut off independently as the load decreases. d) Switching gears in the compressor. e) Decreasing suction in the compressor

c) Divided multipart evaporators which have refrigerant control valves which can be shut off independently as the load decreases.

Which of the following statements about evaporator dampers is true? a) These dampers decrease the resistance to the passage of air. b) When the damper is closed the quantity of air passing over the evaporator coils is at a maximum. c) Depending on the damper position the quantity of air passing through the duct varies widely. d) Multispeed blowers cannot be used in combination with evaporator dampers. e) None of the above

e) None of the above

The type of operation which stops the compressor when the desired low temperature of the substance to be cooled is reached and starts the compressor up again when the temperature rises to a set level is called: a) intermittent operation b) continuous operation with reduced output c) cylinder bypass operation d) unloading operation e) variable guide operation

a) intermittent operation

The control which is replacing suction throttling and operates by swirling the refrigerant in the same direction as the compressor impeller, resulting in a reduction of power required by the compressor is which of the following controls? a) Hot gas bypass b) Cylinder bypass c) Variable Inlet Guide Vanes d) Damper control e) Compressor unloader

c) Variable Inlet Guide Vanes

A simple trap located in the suction line before the compressor that collects liquid, where it evaporates and returns to the compressor as a gas, is called a) an oil separator b) a strainer-drier c) a distributor d) an accumulator e) a stop valve

d) an accumulator

Which of the following statements about strainers is false? a) The strainer is installed in the suction line. b) Piping must be disconnected to clean the strainer. c) Hermetic type compressors are equipped with a built-in suction strainer. d) Strainers typically consist of a fine mesh screen basket. e) Strainers prevent foreign particles from damaging compressor valves

b) Piping must be disconnected to clean the strainer.

A chemical dot placed under the glass lens of a sight glass which is exposed to the liquid serves what function? a) To monitor liquid flow b) To monitor refrigerant levels c) To monitor the presence of moisture d) To monitor the presence of foreign particles e) To monitor the pressure levels

c) To monitor the presence of moisture

The function of vibration absorbers is to: a) lower noise levels b) reduce pipe hammer c) increase longevity of the system d) insulate piping and make the system more efficient e) allow the load on the system to increase dramatically

a) lower noise levels

Which of the following pipe joints should be used for high pressure 1 1/4 inch or smaller piping? a) welded b) screwed c) soldered d) flared e) none of the above

b) screwed

Moisture in a system can result in which of the following? a) formation of ice b) acid formation c) corrosion d) deterioration of motor insulation e) all of the above

e) all of the above

The accessory which maintains efficient heat transfer by collecting oil that coats the tubes of the condenser is called: a) a strainer b) a strainer-drier c) an oil scrubber d) a filter e) an oil separator

e) an oil separator

Which of the following statements about pressure gages is true? a) They indicate pressures and corresponding temperatures in a system. b) Dials on refrigeration pressure gages do not indicate saturation temperature. c) Only one pressure gage is required for each system. d) The pressure gage will not work if the system is equipped with pulsation dampeners. e) None of the above.

a) They indicate pressures and corresponding temperatures in a system.

A direct expansion type evaporator that has more than 1 refrigerant circuit in it requires what to have even refrigerant flow in each circuit? a) A stop valve b) A purge valve c) A distributor d) A purge valve e) A thermal regulator

c) A distributor

Emergency discharge is used to counter which of the following problems? a) Dangerously low system pressures b) Toxic refrigerant leaks c) Combustion of flammable refrigerants d) Dangerously high system pressures e) All of the above

d) Dangerously high system pressures

The emergency discharge line in a refrigeration system: a) is located only on the condenser b) should have a shut-off valve outside the building c) is required on all sizes of refrigerating units d) is located on the evaporator e) is a vented sewer line

b) should have a shut-off valve outside the building

Higher than normal head pressure is undesirable for all of the following reasons except: a) it increases power consumption b) it decreases condenser capacity c) it reduces compressor capacity d) it overstresses compressor parts e) it is detrimental to compressor lubrication

b) it decreases condenser capacity

Which of the following statements about Manual Purging Systems is false? a) They must be operated on a regular schedule. b) The receiver and condenser should be purged separately. c) Purging rids the system of noncondensable gases. d) Refrigerant vapour in the purger is always expelled with the noncondensable gases. e) Gas being vented into the atmosphere must pass through a water beaker.

d) Refrigerant vapour in the purger is always expelled with the noncondensable gases.

The chilling coil in an automatic purger has a primary function to: a) lower the operating temperature of the purger b) keep the system cooling while being purged c) increase the efficiency of the system d) keep discharge through the coil at the lowest available suction pressure e) separate refrigerant vapour from the noncondensable gases to be purged

e) separate refrigerant vapour from the noncondensable gases to be purged

When using lighted sulphur candles to test for ammonia leaks in a refrigeration system, the presence of ammonia will be indicated by: a) a cloud of yellow smoke b) light brown smoke c) heavy white smoke d) heavy black smoke e) light red smoke

c) heavy white smoke

Leak testing for tightness under pressure of a refrigeration system: a) is done by the manufacturer b) is done with oxygen c) is done with ammonia d) is done with an inert gas e) is done with softened water

d) is done with an inert gas

Leak testing on a refrigeration system: a) is done with a sulphur stick for freon refrigerant b) is done with litmus paper for freon c) is done with a sulphur candle for ammonia d) must be done with the compressor running e) is done with a vacuum on the system

c) is done with a sulphur candle for ammonia

Which of the following is not a recommended step for the procedure in which dry nitrogen is used for a system leak test? a) Remove controls and relief valves which may be damaged by the test pressure. b) Connect the nitrogen cylinder to the system charging valve. c) Close the liquid line shut-off valve. d) Open the liquid line shut-off valve. e) Set the pressure reducing valve for the minimum design pressure of the high side.

d) Open the liquid line shut-off valve.

A sulphur candle is a test for: a) freon leaks b) ammonia leaks c) air leaks d) vacuum seal e) CFC leaks

b) ammonia leaks

Before charging a system which of the following needs to be done? a) Interlocks need to be tested b) Controls need to be set c) Controls need to be set d) Required valves need to be opened e) All of the above

e) All of the above

The initial refrigerant charge is given where on the system? a) The high side of the system b) The low side of the system c) The evaporator d) The expansion valve e) The heat exchanger

a) The high side of the system

Frost formation on the suction line indicates what? a) Moisture in the system b) "Copper-Plating" on the bearings and compressor exhaust valve c) Overcharging the system d) Thermostat controlled solenoid deterioration e) Inadequate levels of refrigerant in the system

c) Overcharging the system

The liquid line shutoff valve is: a) used when purging the system b) a regulating valve c) used to relieve pressure d) required to be closed when charging the system e) on top of the receiver

d) required to be closed when charging the system

Charging a refrigeration system: a) is done with the expansion valve closed b) is done by adding refrigerant between the liquid shutoff valve and the expansion valve c) is done with the compressor shut down d) is done between the condenser and the receiver e) is done between the suction valve and the compressor

b) is done by adding refrigerant between the liquid shutoff valve and the expansion valve

When charging a refrigeration system it: a) should be done to the condenser b) should be done with the cooling water shut off c) should be done to the receiver d) should be done with the compressor off e) should be done with the liquid line shutoff valve closed

e) should be done with the liquid line shutoff valve closed

When initially charging a refrigeration system a) it must be done with the liquid line shutoff valve open: b) it is done with a liquid refrigerant c) it must be done after the unit is shut down d) it must be done at the compressor suction e) water should be added to dilute the refrigerant

b) it is done with a liquid refrigerant

What can cause a high discharge pressure with refrigeration systems? a) low evaporator level b) too much cooling water to the condenser c) over-purging the unit d) when unit runs continuously e) unit over-charged with refrigerant

e) unit over-charged with refrigerant

Which of the following statements about adding oil to a system is true? a) Oil is added by charging it into the crankcase. b) Because the crankcase is pressurized it is not possible for air to get in the system when adding oil. c) Oil cannot be added while the compressor is in operation. d) The system must be recharged, purged and repressurized after the oil has been added. e) None of the above

a) Oil is added by charging it into the crankcase.

It is very important to open oil drain valves and plugs in the crankcase for which of the following reasons? a) The oil is very hot. b) The oil is very cold. c) Residual pressure in the crankcase may blow refrigerant vapour and oil out. d) Old oil is contaminated with refrigerant and may be very acidic. e) Oil can never be drained below the critical minimum level.

c) Residual pressure in the crankcase may blow refrigerant vapour and oil out

Oil added to refrigeration compressors: a) is done when the compressor discharge valve is closed b) is done with a vacuum on the crankcase c) is done with the equalizing valve closed d) is done with the charging line open e) must be preheated

b) is done with a vacuum on the crankcase

Which of the following steps is not a step in the startup of a reciprocating or rotary compressor refrigerating system? a) Check oil level in the compressor, it should be at or above the centre of the sight glass. b) Check the setting of high and low pressure cutout switches. c) Open all shutoff valves in the system except bypass valves used elsewhere in the system. d) Valves in lines connecting suction gages should be closed. e) Check oil level in the compressor; it should be below the centre of the sight glass

d) Valves in lines connecting suction gages should be | closed

To avoid liquid slugging in a direct expansion evaporator after shutting down a reciprocating or rotary compressor refrigerating system which of the following measures needs to be taken? a) Pump down the evaporator b) Fill the compressor with liquid refrigerant c) Fill the evaporator with refrigerant vapour d) Open all the suction valves on the connecting condenser line e) Discharge all the condenser refrigerant into the evaporator

a) Pump down the evaporator

Which of the following steps is NOT part of the startup procedure of centrifugal compressor refrigerating systems. a) Check the refrigerant levels. b) Open the stop valves in the chilled water system. c) Open the main circuit breakers. d) Open the makeup water valve. e) Operate the oil pump for at least 10 minutes before starting the compressor

c) Open the main circuit breakers.

A centrifugal compressor refrigerating system can be stopped simply by pressing the stop button unless which of the following circumstances is true? a) The system is automatically controlled. b) The system's auxiliary equipment is not electrically interlocked. c) The system's auxiliary equipment can be stopped simultaneously. d) The compressor can be shut down at the same time as the other equipment. e) None of the above

b) The system's auxiliary equipment is not electrically | interlocked.

The safety control in a centrifugal compressor which ensures the compressor to only be started under a no-load condition is called a) low oil pressure cutout switch b) condenser high pressure cutout c) chilled water flow switch d) motor demand limiter e) vane closed switch

e) vane closed switch

``` If a compressor fails to start but the motor is running, which of the following could be a cause? a) The control circuit is open b) The compressor is seized c) The coupling is sheared or broken d) The motor is burned out e) The starter is defective ```

c) The coupling is sheared or broken

A system of regularly scheduled inspections and lubrications along with the adjustments, minor parts replacement and minor repairs necessary to keep the refrigerating plant and equipment in good operating condition is defined as: a) preventative maintenance b) safety controls c) routing operation d) regular maintenance e) none of the above

a) preventative maintenance

Checking the condition of electrical starters and contactors is categorised under which of the following maintenance schedules? a) Daily maintenance b) Weekly maintenance c) Monthly maintenance d) Semi-annual Maintenance e) Annual maintenance

e) Annual maintenance

``` In an Ammonia Absorption System what is used as the absorbent? a) Ammonia b) Air c) Lithium Bromide d) Water e) Freon ```

d) Wate

Which of the following is not found on the low side of an ammonia system? a) Evaporator b) Generator c) Absorber d) Cooling water e) Low pressure ammonia vapour

b) Generator

Ammonia systems are seldom used for air conditioning purposes in large buildings mainly because: a) ammonia systems require too much maintenance b) ammonia systems are too expensive c) ammonia is too toxic d) ammonia does not provide sufficient cooling power for large operations e) ammonia systems require a separate power supply not available in most large buildings

c) ammonia is too toxic

In comparing absorption and compression systems which of the following comparisons is true? a) Pumps in absorption systems require more electrical power. b) Absorption systems require less space than compression systems. c) Cooling water requirements are larger for an absorption system than for a compression system. d) More equipment and piping are required for a compression system. e) Slugs of liquid carried over from the evaporator do not damage the compression system but can ruin an absorption system.

c) Cooling water requirements are larger for an absorption system than for a compression system.

In a Lithium Bromide System which of the following is the refrigerant? a) Lithium Bromide b) Ammonia c) Freon-22 d) Water e) None of the above

d) Water

In order to lower the boiling point of the refrigerant it is important that the system maintain: a) an extremely high vacuum b) very high pressure c) very low temperatures d) very fast refrigerant flow e) high absorbent circulation

a) an extremely high vacuum

Which of the following statements about Lithium bromide systems is false? a) Lithium bromide solution has the ability to absorb water vapour readily. b) The operating cycle in the system is continuous. c) Evacuating the system lowers the boiling point of water. d) As water vapour is absorbed by the Lithium Bromide the vacuum decreases. e) System efficiency is increased by forcing water through a spray header.

d) As water vapour is absorbed by the Lithium Bromide the vacuum decreases.

The absorber is equipped with a pump for which of the following reasons? a) To force water into a finely divided state b) To keep the cycle pressure constant c) To decrease the refrigerant evaporation point d) To speed the absorption of water vapour e) To decrease contact between absorbent and refrigerant

d) To speed the absorption of water vapour

What is the function of the concentrator (generator)? a) To cool the refrigerant vapour b) To increase the absorbency potential of used LithiumBromide c) To speed up the evaporation of the refrigerant d) To cool the concentrated absorbent e) To exchange heat between the high temperature refrigerant vapour and the atmosphere

b) To increase the absorbency potential of used LithiumBromide

Most absorbency systems are put in place where there is cheap excess or waste heat available. What is this heat primarily used for? a) To pressurize the system b) To maintain the continuous vacuum c) To decrease the evaporation point of the refrigerant d) To run the pumps which force the water through the sprayers e) To evaporate the water out of the weak Lithium Bromide

e) To evaporate the water out of the weak Lithium Bromide

This occurs when the temperature of a strong but still unsaturated solution is lowered so far that its salt concentration exceeds the maximum concentration possible at the lower temperature. a) Ionization b) Dissociation c) Crystallization d) Vapourization e) Neutralization

c) Crystallization

When the temperature of a solution increases, which of the following statements is true? a) The vapour pressure is high b) Less water molecules leave the solution c) The solubility of the salt decreases d) The concentration decreases e) The equilibrium constant decreases

a) The vapour pressure is high

The concentration of Lithium Bromide in an absorption refrigerating system will change during which of the following steps? a) Going through the expansion valve b) Going through the suction valve c) Cooling through the heat exchanger d) Absorbing water vapour in the absorber e) None of the above

d) Absorbing water vapour in the absorber

Concentration of the Lithium Bromide can be most easily controlled by which of the following means? a) Controlling the volume of water sprayed into the absorber. b) Controlling the temperature in the cooling tower. c) Controlling the amount of weak Lithium Bromide pumped into the generator. d) Controlling the pressure in the vacuum between the evaporator and the absorber. e) Controlling the temperature in the generator

e) Controlling the temperature in the generator

Which of the following is NOT a result of having noncondensable gases in the absorption systems? a) Corrosion b) Oxidation of Lithium Bromide c) Lower than normal temperatures of the chilled water leaving the evaporator d) Reduction in capacity of the system e) Crystallization in the heat exchanger

c) Lower than normal temperatures of the chilled water | leaving the evaporator

``` Which of the following are elements of a mechanical purging system? i) purge pickup tube ii) purge chamber iii) manual shutoff valve iv) safety solenoid valve v) oil trap vi) vacuum pump a) i and ii only b) i, ii, and v only c) iv and vi only d) i, iii, and v only Which of the following are elements of a mechanical purging system? i) purge pickup tube ii) purge chamber iii) manual shutoff valve iv) safety solenoid valve v) oil trap vi) vacuum pump a) i and ii only b) i, ii, and v only c) iv and vi only d) i, iii, and v only e) all of the elements ```

e) all of the elements

Which of the following is not a step in the seasonal prestart service? a) clean all cooling and chilled water strainers b) add water treatment chemicals c) turn on energy sources d) check the purge pump e) check the magnetic strainers

c) turn on energy sources

During seasonal startup, when should the purge pump be started? a) Simultaneously with the absorption unit b) One half hour before the absorption unit is started c) At least 24 hours after the compressor is started d) About one half hour after the absorption unit is started e) Only when noncondensables are detected in the system

d) About one half hour after the absorption unit is started

When shutting down the refrigeration system for a weekend or less which of the following is a correct shutdown procedure? a) Drain the cooling water circuit b) Close the manual steam or hot water supply valve c) Service the purge pump d) Open all disconnect switches e) Turn off the air supply to the pneumatic control system

b) Close the manual steam or hot water supply valve

``` If there is a crystallization upon shutdown a possible corrective action is to: a) add octyl alcohol charge b) purge the system c) adjust cooling tower control d) check pump operation e) reduce steam pressure ```

d) check pump operation