UTB12 Refrigeration Flashcards
What term is used for the heat absorbed or given off by a substance while it is changing its physical state?
Latent heat
Which expansion valve controls the liquid refrigerant flow where a flooded evaporator is used?
Low side float expansion valve
Which accessory device consists of a low-pressure bellows or a low-pressure diaphragm connected by a small diagram tube to the compressor?
Compressor-motor control
Which refrigerant has become a replacement for R-12 because it is noncorrosive, nonflammable, practically nontoxic, and has a boiling point of -50°F at atmospheric pressure?
R-502
In what year was the Montreal Protocol amended to establish a schedule for the phase-out of HCFCs?
1992
How often should you weigh a refrigerant cylinder?
Every time refrigerant is discharged
(True or False) Goggles are not required when working with refrigerants.
False
What type of refrigerator has a manual defrost that requires the unit to be turned off to melt the frost buildup on the evaporator?
Single-door fresh food
(True or False) The two basic designs for water coolers, wall mounted and floor mounted, are very different when it comes to construction and operation.
False
What type of acid is formed when refrigerant is mixed with water?
Hydrochloric
U-traps or oil separators should be installed on multiple compressor systems when the condensers are how many feet above the compressor?
10 feet
When transferring refrigerant, the amount of refrigerant that may be placed in a cylinder is what percentage of the tare-weight?
85%
What is the best leak detector to use when trying to detect a halogen refrigerant leak?
Halide leak detector
What unit valve is considered to be obstructed when the unit runs continuously?
Suction valve
What can cause the unit’s compressor to become stuck or tight?
Poor reassembly
(True or False). The coupling on the shaft of direct drive motors should be
realigned after any repair or replacement.
True
Manually defrosting is normally required on refrigeration units that operate at what temperature?
35°F and lower
What does this formula do?
C = (F-32) ÷ 1.8
Formula used to change a Fahrenheit heat reading to a Celsius reading
What type of heat changes the temperature of a substance, but not its physical state?
Sensible
What is the process called, that changes a vapor into a liquid?
Condensation
(True or False) The components of a refrigeration system consist of a compressor, liquid receiver, evaporator, and control devices.
True
What type of refrigeration system compressor is bolted together, has a crankshaft that extends through the crankcase, and is driven by a flywheel and belt?
External drive
or
Open type
Which expansion valve is used to maintain a constant pressure in direct drive and dry type evaporators?
Automatic expansion valve
Which refrigerant is an azeotropic that can only be used with reciprocating compressors?
R-502
Which refrigerant has a boiling point of -55.3°F at atmospheric pressure, and is used to replace R-502 refrigerant?
R-125
(True or False) When storing refrigerants in a cylinder, it is acceptable to use the same regulator for different types of refrigerants.
False
(True or False) Refrigerant cylinders should never be exposed to continuous dampness or salt water.
True
Which type of refrigerator has a storage capacity of 15 cubic feet or greater, and is used at Navy installations to store perishable foods in galleys and messes?
Reach-in
Which type of refrigerator is the most popular and is frost free?
Two-door refrigerator-freezer
(True or False) A common practice is the parallel operation of two or more reciprocating compressors for refrigeration system.
False
(True or False) Using two equalizer lines between the crankcase, on above the normal oil level and one below, is a method of piping that maintains proper oil level in two or more compressors.
True
What size refrigerant shutoff valve, in inches, should be used when transferring refrigerant from the storage cylinder to the service cylinder?
1/4
What is the most sensitive type of leak detector?
Electronic type
(True or False) The first step to follow when disassembling a compressor because of knocking is to expose the top of the piston by removing the cylinder head and valve plate.
True
(True or False) Fan troubles are very hard to locate and correct during compressor inspections.
False
What type of chemical is used in a unit dehydrator to absorb moisture from the refrigerant as it passes through the dehydrator?
Desiccant
Which action should be taken to any loose hinge pins that are found on a unit’s door hinge?
Braiding
(True or False) Operation and maintenance logs should not be used for spotting troubles in refrigeration equipment.
False
(True or False) Maintenance logs can be used to figure future maintenance cost requirements.
True
