DC 3rd Class Test questions and answers with solutions
.
1. The component in which liquid vapor by absorbing heat is called?:
evaporator
2. the best answer for an electrical grounding method?: Metal stake drive 8
foot into the ground.
3. A _____ valve should be used for throttling purposes?: Globe
4. What is the acceptable range for residual sodium sulfite in the boiler
maintain?: 30-70
5. What is the BTU content of a gallon of #4 fuel oil?: 146,000
6. What does a zeolite water softener system use as a means of
regeneration?: brine
7. What are the 4 steps for a Zeolite Rejuvenation water softener process?: -
Backwash, Brine, Rinse, Service
8. Where medium temperature liquid found?: Condenser
9. Where is high temperature vapor found?: At the discharge of the compressor
or condenser
10. What stays are used to support the burner chamber in a scotch marine
boiler?: Diagonal Stays
11. What type of safety valve is this?: ( Full) Crosby nozzle-type safety valve.
Page
365 BOG
12. Where do you get superheat reading?: Take suction line pressure
13. Name the wire that connects all component of a system to a physical
ground or water pipe?: Grounding electrode conductor
14. Where do you get sub-cooling reading?: 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?: 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?: By opening the Quick opening valve first and closing it
Last. 17. ASME Code defines a slow opening valve as what?: One requiring
at least 5 full 360 degree turns between full open and close position.
, DC 3rd Class Test
.
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?: 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?:
once per shift
20. How often do you check the high limit switch?: Annually
21. What is the recommended time for a complete external inspection of a
boiler?: once per shift
22. What is the first thing to do when shutting down a boiler?: To turn off the
fire
23. A flow control should be blown down when?: once per shift
24. How often should you check the Low Water Fuel Cut off?: once per shift
25. Why is oil added to the refrigerant?: lubrication of the compressor
Keep refrigerant migrating
, DC 3rd Class Test
.
.
26. Recycled and filtered refrigerant can be used where?: By the same owner
in the same type of equipment
27. Data printed on the equipment nameplate would include manufacturer,
model, and serial number and________________?: Stamp of approval from
commissioning authority
28. How many BTU's does it take to raise 10 lbs of steam from 40 to 41
degrees?: 1 BTU
29. When working on a boiler, permits should be required?: For every shift
30 How many things do safety controls protect against?: Over pressure Over
Heating
Fire side explosions
31. What chemical compounds in water cause permanent hardness?:
Calcium Sulfate and Magnesium Silicate
32. What chemicals are used to combat corrosion?: sodium sulfite and
hydrazine
33. You have boiler water that is found to have a PH of 5. What compound
do you add to neutralize?: bases
34. What produces soft scale?: calcium carbonate and magnesium carbonate
35. With normal oxygen and low alkalinity, what is added to boiler water?:
Neutralizing Amines
36. What is hard forming scale?: silica
37. Which chemicals are used to combat scale?: Combined Phosphate
Treatment
38. Which compound is not heat produce?: Nitrogen
39. What takes no actual action in combustion?: Nitrogen
40. With hydroxide present & normal oxygen levels; which chemical will
cause problems?: Chlorine
41. What mechanical device is used to remove scale from Fire Tubes?: A Tube
Rattler or Vibrator is used
42. Who can make Adjustments or repairs on a Safety Valve?: Qualify person
from Manufacturer or Representative
43. What mechanical device is used to remove scale from water Tubes?: A
Tube Turbine is used
44. In a duct air handling system, space thermostat control building
temperatures by?: Mixing the air from hot & cold duct in a mixing box serving
.
1. The component in which liquid vapor by absorbing heat is called?:
evaporator
2. the best answer for an electrical grounding method?: Metal stake drive 8
foot into the ground.
3. A _____ valve should be used for throttling purposes?: Globe
4. What is the acceptable range for residual sodium sulfite in the boiler
maintain?: 30-70
5. What is the BTU content of a gallon of #4 fuel oil?: 146,000
6. What does a zeolite water softener system use as a means of
regeneration?: brine
7. What are the 4 steps for a Zeolite Rejuvenation water softener process?: -
Backwash, Brine, Rinse, Service
8. Where medium temperature liquid found?: Condenser
9. Where is high temperature vapor found?: At the discharge of the compressor
or condenser
10. What stays are used to support the burner chamber in a scotch marine
boiler?: Diagonal Stays
11. What type of safety valve is this?: ( Full) Crosby nozzle-type safety valve.
Page
365 BOG
12. Where do you get superheat reading?: Take suction line pressure
13. Name the wire that connects all component of a system to a physical
ground or water pipe?: Grounding electrode conductor
14. Where do you get sub-cooling reading?: 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?: 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?: By opening the Quick opening valve first and closing it
Last. 17. ASME Code defines a slow opening valve as what?: One requiring
at least 5 full 360 degree turns between full open and close position.
, DC 3rd Class Test
.
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?: 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?:
once per shift
20. How often do you check the high limit switch?: Annually
21. What is the recommended time for a complete external inspection of a
boiler?: once per shift
22. What is the first thing to do when shutting down a boiler?: To turn off the
fire
23. A flow control should be blown down when?: once per shift
24. How often should you check the Low Water Fuel Cut off?: once per shift
25. Why is oil added to the refrigerant?: lubrication of the compressor
Keep refrigerant migrating
, DC 3rd Class Test
.
.
26. Recycled and filtered refrigerant can be used where?: By the same owner
in the same type of equipment
27. Data printed on the equipment nameplate would include manufacturer,
model, and serial number and________________?: Stamp of approval from
commissioning authority
28. How many BTU's does it take to raise 10 lbs of steam from 40 to 41
degrees?: 1 BTU
29. When working on a boiler, permits should be required?: For every shift
30 How many things do safety controls protect against?: Over pressure Over
Heating
Fire side explosions
31. What chemical compounds in water cause permanent hardness?:
Calcium Sulfate and Magnesium Silicate
32. What chemicals are used to combat corrosion?: sodium sulfite and
hydrazine
33. You have boiler water that is found to have a PH of 5. What compound
do you add to neutralize?: bases
34. What produces soft scale?: calcium carbonate and magnesium carbonate
35. With normal oxygen and low alkalinity, what is added to boiler water?:
Neutralizing Amines
36. What is hard forming scale?: silica
37. Which chemicals are used to combat scale?: Combined Phosphate
Treatment
38. Which compound is not heat produce?: Nitrogen
39. What takes no actual action in combustion?: Nitrogen
40. With hydroxide present & normal oxygen levels; which chemical will
cause problems?: Chlorine
41. What mechanical device is used to remove scale from Fire Tubes?: A Tube
Rattler or Vibrator is used
42. Who can make Adjustments or repairs on a Safety Valve?: Qualify person
from Manufacturer or Representative
43. What mechanical device is used to remove scale from water Tubes?: A
Tube Turbine is used
44. In a duct air handling system, space thermostat control building
temperatures by?: Mixing the air from hot & cold duct in a mixing box serving
