Compression Refrigeration System Prestart-Up Procedures

Front 1

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

Back 1

B

Front 2

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.

Back 2

D

Front 3

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.

Back 3

E

Front 4

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

Back 4

C

Front 5

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

Back 5

D

Front 6

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

Back 6

C

Front 7

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.

Back 7

D

Front 8

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

Back 8

B

Front 9

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

Back 9

E

Front 10

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

Back 10

A

Front 11

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

Back 11

C

Front 12

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

Back 12

D

Front 13

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

Back 13

B

Front 14

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

Back 14

E

Front 15

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

Back 15

B

Front 16

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

Back 16

E

Front 17

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.

Back 17

A

Front 18

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.

Back 18

C

Front 19

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

Back 19

B