Massachusetts Refrigeration Tech/Contractors practice quiz
Refrigeration RT/RC Prep Quiz
Topics: All categories in the pool
1: An electrical circuit has a 208V power supply and draws 47 amps total, What would be the wattage of the circuit
9,776 watts
.9776 watts
977.6 watts
9.776 watts
2: The level of voltage caused by back electromagnetic force that opens the contacts of a potential relay in order to take the start capacitor out of the circuit is
pick-up voltage
run voltage
boost voltage
lift voltage
3: If the compression ratio on a centrifugal compressor rises too high, the compressor will stop pumping and make a loud sound commonly referred to as a
surge
purge
splurge
merge
4: According to ASHRAE Standard-15 9.8 Positive Displacement Compressor Protection, the pressure-relief device discharge into
the low-pressure side of the system
the high side of the system
the liquid receiver
both a and c are correct
5: What is the purpose of a trap in a vertical discharge line with an upward flow?
start the flow of oil throughout the system
ensure proper oil return to the compressor
Installing a vertical discharge line with an upward flow is prohibited by code
None of the above
6: The main cause of enacting the "no vending rule" of July 1st 1992 was
global warming potential
ozone depletion
both a & b
None of the above
7: Doors communicating with outside from a mechanical room must be?
Self-closing, wooden, fire door
Self-closing, approved, fire door
Self-closing, aligned, fire door
Steel, approved, weather-stripped
8: Fusible plugs must have what marked on them?
Melting temperature in F
Melting temperature in C
Opening pressure
All of the above
9: "I" represents ____ in the Ohm's law formula.
voltage.
resistance
capacitance
amperage
10: How many gallons of water per pound of ammonia do you need?
1
15
5
20
11: If an oil’s floc point is too high, which of the following could occur?
high suction pressure
low head pressure
plugged expansion valve
compressor burn out
12: Class 3 refrigerants are
toxic
non-flammable
highly flammable
non-toxic
13: In a system designed for sub-zero ambient temperatures, what must be added?
Booster compressor
Infrared dye for leak identification
Low-ambient kit
Nitrogen
14: In an ammonia refrigerating system, how is oil pressure adjusted?
Outlet of pump
Inlet of pump
Spring tension of a pressure regulating valve
Both a & b are correct
15: Setting a pressure relief device shall not exceed ___ of the design pressure
80%
90%
75%
100%
16: The first step in mechanical refrigeration is
evaporation
compression
expansion
condensation
17: If the spring is adjusted to increase the superheat, this new setting will
shorten the frost line
have no effect on the frost line
allow more liquid into the evaporator
lengthen the frost line
18: In a motor, an internal overload might open if
there's an excess current draw through the motor
there's a direct short
there was a high pressure refrigerant was used for a low pressure system.
there's an open start winding
19: Pressure relief devices are marked with a ____________ signifying compliance with the ASME Boiler & Pressure Vessel Code.
UL and UM
UM or UL
UL and UR
UV or UR
20: What is not a requirement of a class T machine room?
tight fitting doors
self-closing doors
fire hose connection to the building fire protection system
automatic ventilation
21: A compressor in which the increase in vapor pressure is attained without changing the internal volume of the compression chamber is called
non-volumetric displacement compressor
non-positive displacement compressor
negative displacement compressor
neutral chamber-type compressor
22: A low oil switch is typically
time-delay auto reset
manual reset
automatic reset
non used on semi-hermetic compressors over 10 ton capacity
23: What is the voltage of each leg to ground of a three-phase motor with a 460v supply voltage?
120v
240v
277v
208v
24: What is R-290?
Drop-in replacement for R-134a
Methyl Chloride
Propane
Butane
25: The leaving chilled water set point for comfort cooling is typically?