rd
DC 3 CLASS TEST
QUESTIONS AND CORRECT
ANSWERS LATEST
GUIDE 2026
GRADED A+ .
,1. The component in which liquid vapor by absorbing heat is called?✔✔ CORRECT ANSWER evaporator
2. the best answer for an electrical grounding method?✔✔ CORRECT ANSWER Metal stake drive 8 foot into the ground.
3. A valve should be used for throttling purposes?✔✔ CORRECT ANSWER Globe
4. What is the acceptable range for residual sodium sulfite in the boiler main- tain?✔✔ CORRECT ANSWER
30-70
5. What is the BTU content of a gallon of #4 fuel oil?✔✔ CORRECT ANSWER 146,000
6. What does a zeolite water softener system use as a means of regeneration?-
✔✔ CORRECT ANSWER brine
7. What are the 4 steps for a Zeolite Rejuvenation water softener process?✔✔ CORRECT ANSWER Back- wash, Brine,
Rinse, Service
8. Where medium temperature liquid found?✔✔ CORRECT ANSWER Condenser
9. Where is high temperature vapor found?✔✔ CORRECT ANSWER At the discharge of the compressor or condenser
10. What stays are used to support the burner chamber in a scotch marine boiler?✔✔ CORRECT ANSWER
Diagonal Stays
11. What type of safety valve is this?✔✔ CORRECT ANSWER ( Full) Crosby nozzle-type safety valve. Page 365 BOG
12. Where do you get superheat reading?✔✔ CORRECT ANSWER Take suction line pressure
13. Name the wire that connects all component of a system to a physical ground or water pipe?✔✔ CORRECT ANSWER
Grounding electrode conductor
14. Where do you get sub-cooling reading?✔✔ CORRECT ANSWER 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
15. On the boilers that have both Quick opening and Screw type blow down valves, the Quick opening valve must be
located?✔✔ CORRECT ANSWER closest to the boiler and followed by the screw-type valve
16. High pressure boilers equipped with Quick opening and Screw type valves are blown down how?✔✔ CORRECT
ANSWER By opening the Quick opening valve first and closing it Last.
17. ASME Code defines a slow opening valve as what?✔✔ CORRECT ANSWER Onerequiringatleast5full360degree turns between full
open and close position.
, 18. 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
ANSWER 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
19. During a 24 hours operation how often should you check the water level?✔✔ CORRECT ANSWER once per shift
20. How often do you check the high limit switch?✔✔ CORRECT ANSWER Annually
21. What is the recommended time for a complete external inspection of a boiler?✔✔ CORRECT ANSWER
once per shift
22. What is the first thing to do when shutting down a boiler?✔✔ CORRECT ANSWER To turn ott the fire
23. A flow control should be blown down when?✔✔ CORRECT ANSWER once per shift
DC 3 CLASS TEST
QUESTIONS AND CORRECT
ANSWERS LATEST
GUIDE 2026
GRADED A+ .
,1. The component in which liquid vapor by absorbing heat is called?✔✔ CORRECT ANSWER evaporator
2. the best answer for an electrical grounding method?✔✔ CORRECT ANSWER Metal stake drive 8 foot into the ground.
3. A valve should be used for throttling purposes?✔✔ CORRECT ANSWER Globe
4. What is the acceptable range for residual sodium sulfite in the boiler main- tain?✔✔ CORRECT ANSWER
30-70
5. What is the BTU content of a gallon of #4 fuel oil?✔✔ CORRECT ANSWER 146,000
6. What does a zeolite water softener system use as a means of regeneration?-
✔✔ CORRECT ANSWER brine
7. What are the 4 steps for a Zeolite Rejuvenation water softener process?✔✔ CORRECT ANSWER Back- wash, Brine,
Rinse, Service
8. Where medium temperature liquid found?✔✔ CORRECT ANSWER Condenser
9. Where is high temperature vapor found?✔✔ CORRECT ANSWER At the discharge of the compressor or condenser
10. What stays are used to support the burner chamber in a scotch marine boiler?✔✔ CORRECT ANSWER
Diagonal Stays
11. What type of safety valve is this?✔✔ CORRECT ANSWER ( Full) Crosby nozzle-type safety valve. Page 365 BOG
12. Where do you get superheat reading?✔✔ CORRECT ANSWER Take suction line pressure
13. Name the wire that connects all component of a system to a physical ground or water pipe?✔✔ CORRECT ANSWER
Grounding electrode conductor
14. Where do you get sub-cooling reading?✔✔ CORRECT ANSWER 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
15. On the boilers that have both Quick opening and Screw type blow down valves, the Quick opening valve must be
located?✔✔ CORRECT ANSWER closest to the boiler and followed by the screw-type valve
16. High pressure boilers equipped with Quick opening and Screw type valves are blown down how?✔✔ CORRECT
ANSWER By opening the Quick opening valve first and closing it Last.
17. ASME Code defines a slow opening valve as what?✔✔ CORRECT ANSWER Onerequiringatleast5full360degree turns between full
open and close position.
, 18. 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
ANSWER 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
19. During a 24 hours operation how often should you check the water level?✔✔ CORRECT ANSWER once per shift
20. How often do you check the high limit switch?✔✔ CORRECT ANSWER Annually
21. What is the recommended time for a complete external inspection of a boiler?✔✔ CORRECT ANSWER
once per shift
22. What is the first thing to do when shutting down a boiler?✔✔ CORRECT ANSWER To turn ott the fire
23. A flow control should be blown down when?✔✔ CORRECT ANSWER once per shift
