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DC Third Testing 2023 Update – Questions & Correct Answers
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DC Third Testing 2023 Update – Questions &Correct Answers
The component in which liquid vapor by absorbing heat is called? ✔️Ans -
Evaporator
Select the best answer electrical grounding method? ✔️Ans - Metal stake
drive 8 foot into the ground.
A _____ valve should be used for throttling purpose? ✔️Ans - Globe
What is the acceptable range for residual sodium sulfite in the boiler
maintain? ✔️Ans - 30-70
What is the BTU content of a gallon of #4? ✔️Ans - 146,000
What does a zeolite water softener system use as a means of regeneration?
✔️Ans - Brine
What are the 4 steps for a Zeolite Rejuvenation water softener process?
✔️Ans - Back wash
Backwash, brine, rinse, service
Where is medium temperature is liquid found? ✔️Ans - Condenser
Where is high temperature vapor found? ✔️Ans - At the discharge of the
compressor or condenser
What stays are used to support the burner chamber in a scotch marine boiler?
✔️Ans - Diagonal Stays
What type of safety valve is this? ✔️Ans - ( Full) Crosby nozzle-type
safety valve. Page 365 BOG
What type of safety valve is this? ✔️Ans - ( Full) Crosby nozzle-type
safety valve. Page 365 BOG
,Where do you found superheat reading? ✔️Ans - Take suction line
pressure
Cross reference using a P/T Chart
Get tail coil Temperature
Subtract cross references temperature from tail coil temperature
Result will be superheat
Name the wire that connects all component of a system to a physical ground
or water pipe? ✔️Ans - Grounding Electrode Conductor
Where do get sub-cooling reading? ✔️Ans - 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? ✔️Ans - 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? ✔️Ans - By opening the Quick opening valve first and
closing it Last. Page 403 BOG
ASME Code defines a slow opening valve as what? ✔️Ans - One requiring
at least 5 full 360 degree turns between full open and close position. Page 374
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? ✔️Ans - 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?
✔️Ans - Once per shift
A 15 psi steam boiler produces 8000 pound of steam per hour. The
Minimum pipe size for the pipe leaving the boiler is___12__inches.
(Density is 0.037 lbs/ft3)
Equation: ✔️Ans - D = 12 (C/d/h /.7854)
D = 12 (.037/60) = 3,603.60
D = .ft = 3,927
D = 3.603.,927 = 0.917647058
D = 0.957938963 * 12
D = 11.49 OR 12 "pipe
The boiler steam line is 350 Feet long. During start-up the pipe is heated
From 60 F to 350 F. The 350 F. The pipe wills expand__7.92__inches
Due to the change in temperature
Equation: ✔️Ans - (T 1 - T2) x L x .0000065
(350 - 60) x 350 x .0000065
290 x 350 x 12 x .0000065 = 7.92
A 12" pipe filled with water to a height of 250 feet will have a pressure of
_________at the bottom of the pipe?
Equation:
P = FT / 2.31 ✔️Ans - 250 feet / 2.31 = 108.22
A "5" pipe filled with water to a height of 75 feet will have a pressure of
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