DC 3rd Class Test EXAM Questions and
Answers with complete solution2025(Graded
A+)
The component in which liquid vapor by absorbing heat is called? - CORRECT ANSWERS
evaporator
the best answer for an electrical grounding method? - CORRECT ANSWERS Metal stake drive 8
foot into the ground.
A _____ valve should be used for throttling purposes? - CORRECT ANSWERS Globe
What is the acceptable range for residual sodium sulfite in the boiler maintain? - CORRECT ANSWERS
30-70
What is the BTU content of a gallon of #4 fuel oil? - CORRECT ANSWERS 146,000
What does a zeolite water softener system use as a means of regeneration? - CORRECT ANSWERS
brine
What are the 4 steps for a Zeolite Rejuvenation water softener process? - CORRECT ANSWERS
Backwash, Brine, Rinse, Service
Where medium temperature liquid found? - CORRECT ANSWERS Condenser
Where is high temperature vapor found? - CORRECT ANSWERS At the discharge of the
compressor or condenser
,What stays are used to support the burner chamber in a scotch marine boiler? - CORRECT ANSWERS
Diagonal Stays
What type of safety valve is this? - CORRECT ANSWERS ( Full) Crosby nozzle-type safety valve.
Page 365 BOG
Where do you get superheat reading? - CORRECT ANSWERS Take suction line pressure
Name the wire that connects all component of a system to a physical ground or water pipe? - CORRECT
ANSWERS Grounding electrode conductor
Where do you get sub-cooling reading? - CORRECT ANSWERS Take liquid line pressure
Cross reference to temperature using a P/T Chart
Get liquid line temperature
Subtract actual temperature from cross referenced temperature
Result is Sub cooling
On the boilers that have both Quick opening and Screw type blow down valves, the Quick opening valve
must be located? - CORRECT ANSWERS closest to the boiler and followed by the screw-type valve
High pressure boilers equipped with Quick opening and Screw type valves are blown down how? -
CORRECT ANSWERS By opening the Quick opening valve first and closing it Last.
ASME Code defines a slow opening valve as what? - CORRECT ANSWERS One requiring at least 5
full 360 degree turns between full open and close position.
, A 300 Horsepower boiler operating at 100psi has an average load of 75% with 80% condensate return
and 5% blow down. The treatment provides a chemical which costs $8.75 per gallon, and will treat 600
gallon. Find the amount of the chemical needed for the day period, and the cost of the chemical for a 30
days period? - CORRECT ANSWERS Water In = Water Out
Makeup + Condensate Return = Evaporator + Blow Down
Average Evaporator Rate = 300 x 34.5 pph x .75% load = 7762, 50 pph
1 Month + .8( 7762.50 pph) = 7762.50 pph + 0500 m
1 Month + 6210 pph = 7762.50 pph + .0500 m
-6210 -6210
1 Month = 1552.5 pph + .0500
.9500 m = 1552.5 pph
.9500m .9500
1Month = 1,634.21 pph
Gallons per Month = 1634..33 x 24 x 30 = 141, 252.24 gallons per month
Chemical needed = 141,252.24 gallon / 600 gallon = 235, 40 gallon
Cost per month = 235, 40 gallon x 8.75 = $2,059.75
During a 24 hours operation how often should you check the water level? - CORRECT ANSWERS
once per shift
Answers with complete solution2025(Graded
A+)
The component in which liquid vapor by absorbing heat is called? - CORRECT ANSWERS
evaporator
the best answer for an electrical grounding method? - CORRECT ANSWERS Metal stake drive 8
foot into the ground.
A _____ valve should be used for throttling purposes? - CORRECT ANSWERS Globe
What is the acceptable range for residual sodium sulfite in the boiler maintain? - CORRECT ANSWERS
30-70
What is the BTU content of a gallon of #4 fuel oil? - CORRECT ANSWERS 146,000
What does a zeolite water softener system use as a means of regeneration? - CORRECT ANSWERS
brine
What are the 4 steps for a Zeolite Rejuvenation water softener process? - CORRECT ANSWERS
Backwash, Brine, Rinse, Service
Where medium temperature liquid found? - CORRECT ANSWERS Condenser
Where is high temperature vapor found? - CORRECT ANSWERS At the discharge of the
compressor or condenser
,What stays are used to support the burner chamber in a scotch marine boiler? - CORRECT ANSWERS
Diagonal Stays
What type of safety valve is this? - CORRECT ANSWERS ( Full) Crosby nozzle-type safety valve.
Page 365 BOG
Where do you get superheat reading? - CORRECT ANSWERS Take suction line pressure
Name the wire that connects all component of a system to a physical ground or water pipe? - CORRECT
ANSWERS Grounding electrode conductor
Where do you get sub-cooling reading? - CORRECT ANSWERS Take liquid line pressure
Cross reference to temperature using a P/T Chart
Get liquid line temperature
Subtract actual temperature from cross referenced temperature
Result is Sub cooling
On the boilers that have both Quick opening and Screw type blow down valves, the Quick opening valve
must be located? - CORRECT ANSWERS closest to the boiler and followed by the screw-type valve
High pressure boilers equipped with Quick opening and Screw type valves are blown down how? -
CORRECT ANSWERS By opening the Quick opening valve first and closing it Last.
ASME Code defines a slow opening valve as what? - CORRECT ANSWERS One requiring at least 5
full 360 degree turns between full open and close position.
, A 300 Horsepower boiler operating at 100psi has an average load of 75% with 80% condensate return
and 5% blow down. The treatment provides a chemical which costs $8.75 per gallon, and will treat 600
gallon. Find the amount of the chemical needed for the day period, and the cost of the chemical for a 30
days period? - CORRECT ANSWERS Water In = Water Out
Makeup + Condensate Return = Evaporator + Blow Down
Average Evaporator Rate = 300 x 34.5 pph x .75% load = 7762, 50 pph
1 Month + .8( 7762.50 pph) = 7762.50 pph + 0500 m
1 Month + 6210 pph = 7762.50 pph + .0500 m
-6210 -6210
1 Month = 1552.5 pph + .0500
.9500 m = 1552.5 pph
.9500m .9500
1Month = 1,634.21 pph
Gallons per Month = 1634..33 x 24 x 30 = 141, 252.24 gallons per month
Chemical needed = 141,252.24 gallon / 600 gallon = 235, 40 gallon
Cost per month = 235, 40 gallon x 8.75 = $2,059.75
During a 24 hours operation how often should you check the water level? - CORRECT ANSWERS
once per shift
