B-09: Basic Concepts Of Compression And Absorption

Question 1

(4-118-1.2) The refrigeration compressors operating control that uses a bimetal element is a:

A. Fluid expansion actuating control
B. Pressurestat
C. Humidistat
D. Temperature actuated control

Answer 1

D. Temperature actuated control

Question 2

Which of the following statements is true about oil pots?

A. Oil pots are pressure vessels that trap oil
B. Oil pots are atmospheric vessels that trap oil
C. Oil pots feature an increasing frost line as the accumulate refrigerant from the system
D. Oil pots feature a decreasing front line as they accumulate oil from the system

Answer 2

A. Oil pots are pressure vessels that trap oil

Question 3

(4-117-2-4) The refrigeration condenser design that requires chemical cleaning, because it cannot be mechanically cleaned, is the:

A. Shell and tube condenser
B. Shell and coil condenser
C. Air-cooled condenser
D. Evaporative condenser

Answer 3

B. Shell and coil condenser

Question 4

During manual pump down of a refrigeration system, why is the low-side pressure rarely reduced below atmospheric pressure ?

A. Air may be drawn in and damage components
B. Cooling water has to be kept running on the condenser
C. Compound gauges cannot indicate below atmospheric pressure
D. Refrigerant may escape into surrounding areas

Answer 4

A. Air may be drawn in and damage components

Question 5

(4-113-2.1) The function of the condenser in a refrigeration system is to:

A. Lower the temperature of the liquid refrigerant
B. Change high pressure refrigerant vapour to liquid
C. Lower the temperature of the refrigerant vapour
D. Lower the liquid refrigerant pressure

Answer 5

B. Change high pressure refrigerant vapour to liquid

Question 6

(4-114-1.11) The refrigerant R-134A belongs to the following safety group:

A. A2
B. B1
C. A3
D. A1

Answer 6

D. A1

Question 7

Which type of refrigeration system has the evaporator surface in direct contact with the material or space being refrigerated ?

A. Industrial refrigerator
B. Direct
C. House refrigerator
D. Indirect

Answer 7

B. Direct

Question 8

The presence of ammonia in the brine system is an indication of:

A. A refrigerant that is suitable for temperatures above 0 degrees Celsius
B. A leak in the primary refrigerant piping
C. A weak brine concentration; more calcium chloride should be added
D. A refrigerant that is suitable for temperature below 0 degrees Celsius

Answer 8

B. A leak in the primary refrigerant piping

Question 9

(4-116-1.4) The safety head of a refrigeration compressor is designed to:

A. Unload cylinders if over-loaded
B. Relieve pressure due to liquid in the cylinder
C. Prevent damage due to freeze-up
D. Take the place of a safety relief valve

Answer 9

B. Relieve pressure due to liquid in the cylinder

Question 10

What is used to raise the refrigerant vapour pressure in an absorption refrigeration system?

A. Compressor
B. Evaporator
C. Absorber
D. Generator

Answer 10

D. Generator

Question 11

(4-122-2.3) If the chilled water temperature drops approximately 2.5-3 Degrees C below the chilled water temperature set point, the chilled water low temperature cut out will:

A. Start the compressor
B. Shut down the compressor
C. Stop the chilled water pumps
D. Start the condenser pump

Answer 11

B. Shut down the compressor

Question 12

(4-113-1.8) Refrigerants will evaporate when the:

A. Pressure is increased
B. Temperature is increased to saturation temperature
C. Temperature is reduced below saturation temperature
D. Heat is removed from them

Answer 12

B. Temperature is increased to saturation temperature

Question 13

(4-113-1.2) Heat that causes an increase in temperature, is called _____ heat:

A. Radiant
B. Sensible
C. Latent
D. Convective

Answer 13

B. Sensible

Question 14

The major building occupancy classes include all of the following, except:

A. Industrial
B. Educational
C. Commercial
D. Institutional

Answer 14

B. Educational

Question 15

(4-123-2.1) Absorption refrigeration systems may use waste heat in order to:

A. Pressurize the system
B. Evaporate water from the weak lithium bromide
C. Decrease the evaporation point of the refrigerant
D. Maintain a minimum load on the system, during periods of low cooling demand
E. Increase the lithium boiling point

Answer 15

B. Evaporate water from the weak lithium bromide

Question 16

(4-113-1.9) The two major types of compression refrigeration systems are:

A. Frosting and non-frosting
B. Commercial and residential
C. Indirect and direct
D. High pressure and low pressure

Answer 16

C. Indirect and direct

Question 17

What does the pH of brine indicate ?

A. Potential corrosion problems
B. Air leak into the system
C. High concentration of solids
D. Strength of the brine

Answer 17

A. Potential corrosion problems

Question 18

(4-123-2.3) In order to lower the boiling point of the refrigerant in the lithium bromide refrigeration system, it is important that the system maintain:

A. An extremely high vacuum
B. Very high pressure
C. Very low temperatures
D. High absorbent circulation rates

Answer 18

A. An extremely high vacuum

Question 19

What must be located outside a Class T machinery room?

A. Spare flashlights
B. Light switches
C. Disposable coveralls
D. Machinery shut off switch

Answer 19

D. Machinery shut off switch

Question 20

Which of the following is NOT an optional component of a refrigeration system?

A. A condenser cooling fan
B. An evaporator fan
C. A liquid receiver
D. An evaporator

Answer 20

D. An evaporator