2014 update DC Third testing Questions And
Answers
The component in which liquid vapor by absorbing heat is called? - (correct answer) -Evaporator
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Select the best answer electrical grounding method? - (correct answer) -Metal stake drive 8 foot into
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the ground.
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A _____ valve should be used for throttling purpose? - (correct answer) -Globe
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What is the acceptable range for residual sodium sulfite in the boiler maintain? - (correct answer) -30-
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70
What is the BTU content of a gallon of #4? - (correct answer) -146,000
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What does a zeolite water softener system use as a means of regeneration? - (correct answer) -Brine
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What are the 4 steps for a Zeolite Rejuvenation water softener process? - (correct answer) -Back wash
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hi Backwash, brine, rinse, service hi hi hi
Where is medium temperature is liquid found? - (correct answer) -Condenser
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Where is high temperature vapor found? - (correct answer) -At the discharge of the compressor or
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condenser
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What stays are used to support the burner chamber in a scotch marine boiler? - (correct answer) -
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Diagonal Stays hi
What type of safety valve is this? - (correct answer) -( Full) Crosby nozzle-type safety valve. Page 365
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BOG
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What type of safety valve is this? - (correct answer) -( Full) Crosby nozzle-type safety valve. Page 365
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BOG
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Where do you found superheat reading? - (correct answer) -Take suction line pressure
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hi Cross reference using a P/T Chart
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hi Get tail coil Temperature
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,hi Subtract cross references temperature from tail coil temperature
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hi Result will be superheat hi hi hi
Name the wire that connects all component of a system to a physical ground or water pipe? - (correct
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answer) -Grounding Electrode Conductor
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Where do get sub-cooling reading? - (correct answer) -Take liquid line pressure
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hi Cross reference to temperature using a P/T Chart
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hi Get liquid line temperature
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Subtract actual temperature from cross referenced temperature
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hi Result is sub-cooling hi hi
On the boilers that have both Quick opening and Screw type blow down valves, the Quick opening
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valve must be located? - (correct answer) -Closest to the boiler and followed by the screw type valve
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High pressure boilers equipped with Quick opening and Screw type valves are blown down how? -
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(correct answer) -By opening the Quick opening valve first and closing it Last. Page 403 BOG
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ASME Code defines a slow opening valve as what? - (correct answer) -One requiring at least 5 full 360
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degree turns between full open and close position. Page 374
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A 300 Horsepower boiler operating at 100psi has an average load of 75% with 80% condensate return
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and 5% blow down. The treatment provides a chemical which costs $8.75 per gallon, and will treat
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600 gallon. Find the amount of the chemical needed for the day period, and the cost of the chemical
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for a 30 days period? - (correct answer) -Water In = Water Out
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Makeup + Condensate Return = Evaporator + Blow Downhi hi hi hi hi hi hi hi
Average Evaporator Rate = 300 x 34.5 pph x .75% load = 7762, 50 pph
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1 Month + .8( 7762.50 pph) = 7762.50 pph + 0500 m
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1 Month + 6210 pph = 7762.50 pph + .0500 m
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hi -6210 -6210 hi
1 Month = 1552.5 pph + .0500
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, .9500 m = 1552.5 pph hi hi hi hi
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1Month = 1,634.21 pph hi hi hi
Gallons per Month = 1634..33 x 24 x 30 = 141, 252.24 gallons per month
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Chemical needed = 141,252.24 gallon / 600 gallon = 235, 40 gallon
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Cost per month = 235, 40 gallon x 8.75 = $2,059.75
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During a 24 hours operation how often should you check the water level? - (correct answer) -Once per
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shift
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A 15 psi steam boiler produces 8000 pound of steam per hour. The
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hi Minimum pipe size for the pipe leaving the boiler is___12__inches.
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hi (Density is 0.037 lbs/ft3) hi hi hi
hi Equation: - (correct answer) -D = 12 (C/d/h /.7854) hi hi hi hi hi hi hi hi
hi D = 12 (.037/60) = 3,603.60
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hi D = .ft = 3,927
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hi D = 3.603.,927 = 0.917647058
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hi D = 0.957938963 * 12
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hi D = 11.49 OR 12 "pipe
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The boiler steam line is 350 Feet long. During start-up the pipe is heated
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hi From 60 F to 350 F. The 350 F. The pipe wills expand__7.92__inches
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hi Due to the change in temperature
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hi Equation: - (correct answer) -(T 1 - T2) x L x .0000065
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hi (350 - 60) x 350 x .0000065
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