DC 3RD CLASS TEST QUESTIONS AND ANSWERS
The component in which liquid vapor by absorbing heat is called? - Answers-
evaporator
the best answer for an electrical grounding method? - Answers- Metal stake drive 8 foot
into the ground.
A _____ valve should be used for throttling purposes? - Answers- Globe
What is the acceptable range for residual sodium sulfite in the boiler maintain? -
Answers- 30-70
What is the BTU content of a gallon of #4 fuel oil? - Answers- 146,000
What does a zeolite water softener system use as a means of regeneration? -
Answers- brine
What are the 4 steps for a Zeolite Rejuvenation water softener process? - Answers-
Backwash, Brine, Rinse, Service
Where medium temperature liquid found? - Answers- Condenser
Where is high temperature vapor found? - Answers- At the discharge of the compressor
or condenser
What stays are used to support the burner chamber in a scotch marine boiler? -
Answers- Diagonal Stays
On the boilers that have both Quick opening and Screw type blow down valves, the
Quick opening valve must be located? - 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? - Answers- By opening the Quick opening valve first and closing it Last.
ASME Code defines a slow opening valve as what? - 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? - 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? - Answers-
once per shift
How often do you check the high limit switch? - Answers- Annually
What type of safety valve is this? - Answers- ( Full) Crosby nozzle-type safety valve.
Page 365 BOG
Where do you get superheat reading? - Answers- Take suction line pressure
Name the wire that connects all component of a system to a physical ground or water
pipe? - Answers- Grounding electrode conductor
Where do you get sub-cooling reading? - 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
What is the recommended time for a complete external inspection of a boiler? -
Answers- once per shift
What is the first thing to do when shutting down a boiler? - Answers- To turn off the fire
A flow control should be blown down when? - Answers- once per shift
How often should you check the Low Water Fuel Cut off? - Answers- once per shift
, Why is oil added to the refrigerant? - Answers- lubrication of the compressor
Keep refrigerant migrating
Recycled and filtered refrigerant can be used where? - Answers- By the same owner in
the same type of equipment
Data printed on the equipment nameplate would include manufacturer, model, and
serial number and________________? - Answers- Stamp of approval from
commissioning authority
How many BTU's does it take to raise 10 lbs of steam from 40 to 41 degrees? -
Answers- 1 BTU
When working on a boiler, permits should be required? - Answers- For every shift
How many things do safety controls protect against? - Answers- Over pressure
Over Heating
Fire side explosions
What chemical compounds in water cause permanent hardness? - Answers- Calcium
Sulfate and Magnesium Silicate
What chemicals are used to combat corrosion? - Answers- sodium sulfite and
hydrazine
You have boiler water that is found to have a PH of 5. What compound do you add to
neutralize? - Answers- bases
What produces soft scale? - Answers- calcium carbonate and magnesium carbonate
With normal oxygen and low alkalinity, what is added to boiler water? - Answers-
Neutralizing Amines
What is hard forming scale? - Answers- silica
Which chemicals are used to combat scale? - Answers- Combined Phosphate
Treatment
Which compound is not heat produce? - Answers- Nitrogen
What takes no actual action in combustion? - Answers- Nitrogen
With hydroxide present & normal oxygen levels; which chemical will cause problems? -
Answers- Chlorine
The component in which liquid vapor by absorbing heat is called? - Answers-
evaporator
the best answer for an electrical grounding method? - Answers- Metal stake drive 8 foot
into the ground.
A _____ valve should be used for throttling purposes? - Answers- Globe
What is the acceptable range for residual sodium sulfite in the boiler maintain? -
Answers- 30-70
What is the BTU content of a gallon of #4 fuel oil? - Answers- 146,000
What does a zeolite water softener system use as a means of regeneration? -
Answers- brine
What are the 4 steps for a Zeolite Rejuvenation water softener process? - Answers-
Backwash, Brine, Rinse, Service
Where medium temperature liquid found? - Answers- Condenser
Where is high temperature vapor found? - Answers- At the discharge of the compressor
or condenser
What stays are used to support the burner chamber in a scotch marine boiler? -
Answers- Diagonal Stays
On the boilers that have both Quick opening and Screw type blow down valves, the
Quick opening valve must be located? - 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? - Answers- By opening the Quick opening valve first and closing it Last.
ASME Code defines a slow opening valve as what? - 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? - 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? - Answers-
once per shift
How often do you check the high limit switch? - Answers- Annually
What type of safety valve is this? - Answers- ( Full) Crosby nozzle-type safety valve.
Page 365 BOG
Where do you get superheat reading? - Answers- Take suction line pressure
Name the wire that connects all component of a system to a physical ground or water
pipe? - Answers- Grounding electrode conductor
Where do you get sub-cooling reading? - 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
What is the recommended time for a complete external inspection of a boiler? -
Answers- once per shift
What is the first thing to do when shutting down a boiler? - Answers- To turn off the fire
A flow control should be blown down when? - Answers- once per shift
How often should you check the Low Water Fuel Cut off? - Answers- once per shift
, Why is oil added to the refrigerant? - Answers- lubrication of the compressor
Keep refrigerant migrating
Recycled and filtered refrigerant can be used where? - Answers- By the same owner in
the same type of equipment
Data printed on the equipment nameplate would include manufacturer, model, and
serial number and________________? - Answers- Stamp of approval from
commissioning authority
How many BTU's does it take to raise 10 lbs of steam from 40 to 41 degrees? -
Answers- 1 BTU
When working on a boiler, permits should be required? - Answers- For every shift
How many things do safety controls protect against? - Answers- Over pressure
Over Heating
Fire side explosions
What chemical compounds in water cause permanent hardness? - Answers- Calcium
Sulfate and Magnesium Silicate
What chemicals are used to combat corrosion? - Answers- sodium sulfite and
hydrazine
You have boiler water that is found to have a PH of 5. What compound do you add to
neutralize? - Answers- bases
What produces soft scale? - Answers- calcium carbonate and magnesium carbonate
With normal oxygen and low alkalinity, what is added to boiler water? - Answers-
Neutralizing Amines
What is hard forming scale? - Answers- silica
Which chemicals are used to combat scale? - Answers- Combined Phosphate
Treatment
Which compound is not heat produce? - Answers- Nitrogen
What takes no actual action in combustion? - Answers- Nitrogen
With hydroxide present & normal oxygen levels; which chemical will cause problems? -
Answers- Chlorine
