DC Boiler/Stationary Exam Questions and Answers: 2024-2025, Exams of Public Health

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DC BOILER/STATIONARY EXAM 2024-2025 QUESTIONS AND CORRECTVERIFIED ANSWERS /100% PASS SOLUTION / ALREADY GRADED A+

Which element does not take an actual action in the combustion process? - ANSWER-nitrogen Immediately after a repair to a refrigeration system what is used to remove moisture From thesystem? - ANSWER-vacuum pump

The boiler steam line is 450 feet long. During start up the pipe is heated from 70F to360F. how many inches the pipe will expand? - ANSWER-Formula: Exp in = (T1 - T2) x L x 0.0000065= 360 - 70 x (450x12) x 0. = 290 x 5400 x 0.0000065 = 10.18?

What would you add to a boiler, if you are needed to the protect the refractory from Excessheat and to increase the capacity of the boiler? - ANSWER-Riser tubes

A condensate tank has a lot of steam existing from its vent it is registering 20 F higher Thannormal. What could be the reason? - ANSWER-Steam trap failing open What kind of valve allows a boiler to be "cut in online" when the main isolation valve is Open orclosed?

• ANSWER-Stop check valve In a siphon, what is the water seal between the boiler and the pressure controls called? -ANSWER- Condensate

What is the formula to find a volume of cylinder? - ANSWER-Formula or equation is: V = Area ofa circle X High or Length. Where V: volumeArea of a circle is: A = (D² X 0.7854) For example: What is the volume of a cylinder tank that has a 15" diameter and 30" high? V = (15x15x0.7854)x 30 V = 176.715 x 30V = 5301.45 in³ " 15 To get gallonsG = 5301.45 ÷ 231 G = 22.9530"

How many cubic inches are in a gallon? - ANSWER-There are 231 cu in. of water in a gallon. Toconvert cubic inches to gallons, divide cubic Inches by 231. To convert gallons to cubic inches, multiply gallons by 231. For example: What isthe volume of a rectangle tank that is 30 inches base, 24 inches high, and 60 Inches deep. Andwhat is the capacity in gallons? Formula to find volume of rectangle is: V = Base X High X Length V = 30 X 24 X 60

V = 43,200 cu in³Where 231 in³ = 1 gallon 43200 ÷ 231 = 187.01 gallons 60 in There is an example. How calculate a boiler horsepower. - ANSWER-A boiler has an output. Theboiler horsepower of a boiler generating 18,000 lbs of

What is the area of a triangle with a base of 45" and a height of 26"? - ANSWER-A = ½ x Base xHeight A = ½ x 45 x 26 A = 585 in² What is the volume of a cylindrical tank that has a 60" diameter and a 72" Length? - ANSWER-Formula = V = Area of a circle x Length V = 60 x 60 x 0.7854 x 72 V = 203,575.68 in³ What is the volume of a cylindrical tank that has a 24" diameter and a 48" Length? - ANSWER-Formula = V = Area of a circle x Length V = 24 x 24 x 0.7854 x 48 V = 21,714.74 in³ What is the total force acting on a 2" pressure relief valve with a popping Pressure of 125 psi? -ANSWER-Formula = TF = P x A TF = P x (d x d x 0.7854) TF = 125 x (2 x 2 x 0.7854) TF = 392.7 lbs What is the total force acting on a 4½" pressure relief valve with a popping Pressure of 500 psi?- ANSWER-Formula = TF = P x A TF = P x (d x d x 0.7854)

TF = 500 x (4½ x 4½ x 0.7854) TF = 7,952.17 lbs At what pressure will a 3" pressure relief valve lift with a 1500-pound spring? - ANSWER-Formula = P = TF ÷ A P = 1500 ÷ (3 x 3 x 0.7854)P = 1500 ÷ 7.07 P = 212.20 psi At what pressure will a 2½" pressure relief valve lift with a 6500-pound spring? - ANSWER-Formula = P = TF ÷ A

P = 6500 ÷ (2½ x 2½ x 0.7854) P = 6500 ÷ 4.91P = 1,324.17 psi

92°C =? - ANSWER-°F = (°C x 1.8) + 32 F = (92 x 1.8) + 32F = 197.6°F

31°C =? - ANSWER-°F F = (°C x 1.8) + 32F = (31 x 1.8) + 32 F = 55.8 + 32 F = 87.8°F 60°F =?°C - ANSWER-C = (°F - 32) ÷ 1.8 C = (60 - 32) ÷ 1.8C = 28 ÷ 1.

C = 15.55°C 185°F =?°C - ANSWER-C = (°F - 32) ÷ 1.8 C = (185 - 32) ÷ 1.8C = 153 ÷ 1.8 C = 85°C 85°F =? °Rankin - ANSWER-R = °F + 460 R = 85 + 460R = 545°

A pump moving 250 gpm of water to a height of 75 feet with an operatingEfficiency of 96% will require how many horsepower? - ANSWER-HP = GPM x 8.33 x Height 33000 x Eғғ

GPM = 32868.99 231

GPM = 142.29 gpm. 162.5% slip. What is the capacity of the pump? - ANSWER-GPM = LANE 231 A duplex reciprocating pump runs at 200 rpm. The pump is a 15 x 8 x 20, Operating with GPM = 20 x (8 x 8 x 0.7854) x 200 x 2 x (1 - 0.05) 231

GPM = 382018.56 231

GPM = 1,653.76 gpm 163.develop when operating with 75-psi steam? - ANSWER-Pw = Ps x As What is the maximum pressure that a 12 x 5 x 15 duplex reciprocating pump Can Aw Pw = 75 x (12 x 12 x 0.7854)(5 x 5 x 0.7854)

Pw = 8482.3219.

Pw = 432 psi. What is the maximum pressure that a 15 x 9 x 10 duplex reciprocating pump Can develop whenoperating with 125-psi steam? - ANSWER-Pw = Ps x As Aw Pw = 125 x (15 x 15 x 0.7854)(9 x 9 x 0.7854)

Pw = 22089.3863.

Pw = 347.22 psi.

165. What is the flow rate, in gallons per minute, of water flowing through a 4' pipe

At a velocity of 12 feet per second? - ANSWER-GPM = V X D² 0. GPM = 12 x (4 x 4)0.

A 12" pipe filled with water to a height of 250 feet will have a pressure of 250 feet / 2.31 = 108.22at the bottom of the pipe? - ANSWER-Equation: P = FT / 2. A 15 psi steam boiler produces 8000 pound of steam per hour. The Minimum pipe size for thepipe leaving the boiler is 12 inches. (Density is 0.037 lbs/ft3) Equation: - ANSWER-D = 12 (C/d/h /.7854) D = 12 (8000 / 0.037/60) = 3,603.60D = .7854 / 5000ft = 3, D = 3.603.60 / 3,927 = 0.917647058D = 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: - ANSWER-(T 1 - T2) x L x .0000065 (350 - 60) x 350 x .0000065290 x 350 x 12 x .0000065 = 7.

A water analysis determines that there is 75 ppm calcium, and 42 ppm Magnesium, The totalhardness as equivalent ppm of calcium carbonate Would be ppm. - ANSWER-Equation:

TH = Total HardnessTH = (C x 2.5) + (M x 4.1) TH = 75 x 2.5 + 42 x 4. TH = 187.5 + 172.2 TH = 359.7 TH

What is the normal sodium sulfite in a boiler? - ANSWER-20- Where is the cooling tower bleed line? - ANSWER-Drain line Plume discharges from the cooling tower shall not less than? - ANSWER-5 feet How is fire tube in a boiler secured? - ANSWER-To the tube sheet What kind of steam trap has a simple float/disc that lifts? - ANSWER-Inverted bucket A test on a 2" ID size pipe showed that the flow velocity was 140 feet Per second, as measuredby an orifice plate. What is the gallon per Minute flow rate? - ANSWER-GPM = 2" x 2" x .7854 x 140ft/sec x 12in / ft x60 sec / min 231cubic inches / gallon GPM = 1370.88 GPM If a pump has an efficiency of 70%, and delivers 1500 gpm of water From ground level against atotal head of 1000 feet, what is the Required motor horsepower? - ANSWER-Horsepower = GPM x 8.33 x Height x Specific Gravity33,000 x Efficiency Horsepower = 1500 x 8.33 x 1000

33,000 x .70Horsepower = 540.

What jumper is used to connect the neutral and ground? - ANSWER-Main Bonding Jumper Every discharge pipe on a safety valve should be at least? - ANSWER-Every discharge pipe on asafety valve should be at least?6 feet high

What is pump slip? - ANSWER-The difference the pumps theoretical and actual pumpdisplacement

What is Shear = is the exertion of equal forces in opposite direction in the same plane. -ANSWER-189. Page 159 BOG

190. Page 628 BOG # 185°C =? °Kelvin - ANSWER-K = C + 273 K = 185 + 273K = 458° The component in which liquid vapor by absorbing heat is called? - ANSWER-Evaporator Select the best answer electrical grounding method? - ANSWER-Metal stake drive 8 foot intothe ground.

A valve should be used for throttling purpose? - ANSWER-Globe What is the acceptable range for residual sodium sulfite in the boiler maintain? - ANSWER-30- 70

What is the BTU content of a gallon of #4? - ANSWER-146, What does a zeolite water softener system use as a means of regeneration? - ANSWER-Brine What are the 4 steps for a Zeolite Rejuvenation water softener process? - ANSWER-Back washBackwash, brine, rinse, service Where is medium temperature is liquid found? - ANSWER-Condenser Where is high temperature vapor found? - ANSWER-At the discharge of the compressor orcondenser

What stays are used to support the burner chamber in a scotch marine boiler? - ANSWER-Diagonal Stays

What type of safety valve is this? - ANSWER-( Full) Crosby nozzle-type safety valve. Page 365BOG

What type of safety valve is this? - ANSWER-( Full) Crosby nozzle-type safety valve. Page 365BOG

Where do you found superheat reading? - ANSWER-Take suction line pressure Cross referenceusing a P/T Chart Get tail coil Temperature

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 - 1 Month = 1552.5 pph +. .9500 m = 1552.5 pph.9500m.

1Month = 1,634.21 pph Gallons per Month = 1634.21 / 8.33 x 24 x 30 = 141, 252.24 gallons per monthChemical needed = 141,252.24 gallon / 600 gallon = 235, 40 gallon

Cost per month = 235, 40 gallon x 8.75 = $2,059. During a 24 hours operation how often should you check the water level? - ANSWER-Once pershift

A 15 psi steam boiler produces 8000 pound of steam per hour. The Minimum pipe size for thepipe leaving the boiler is 12 inches. (Density is 0.037 lbs/ft3)

Equation: - ANSWER-D = 12 (C/d/h /.7854) D = 12 (8000 / 0.037/60) = 3,603.60D = .7854 / 5000ft = 3,

D = 3.603.60 / 3,927 = 0.917647058D = 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: - ANSWER-(T 1 - T2) x L x .0000065 (350 - 60) x 350 x .0000065290 x 350 x 12 x .0000065 = 7.

A 12" pipe filled with water to a height of 250 feet will have a pressure of P = FT / 2.31 - ANSWER-250 feet / 2.31 = 108.22at the bottom of the pipe? Equation: A "5" pipe filled with water to a height of 75 feet will have a pressure of The bottom of the pipe?at Equation:P = FT / 2.31 - ANSWER-75 feet / 2.31 = 32.

GPM = 470.01 gpm What is the maximum pressure that a 15 x 9 x 10 duplex reciprocating pump Can develop whenoperating with 125-psi steam? - ANSWER-Pw = Ps x As Aw Pw = 125 x (15 x 15 x 0.7854)(9 x 9 x 0.7854)

Pw = 22089.

Pw = 347.22 psi. During a 24 hours operation how often should you check the water level? - ANSWER-Once pershift

How often you checking the high limit switch? - ANSWER-Annually What is the recommended time for a complete external inspection of a boiler? - ANSWER-Onceper shift

What is the first thing to do when shutting down a boiler? - ANSWER-Turn of the fire A flow control should be blown down when? - ANSWER-Once per shift How often should you check the Low Water Fuel Cut off? - ANSWER-Once per shift Why is oil added to the refrigerant? - ANSWER-To lubrication of the compressor Keeprefrigerant migrating Recycled and filtered refrigerant can be used where? - ANSWER-By the same owner in the sametype of equipment

Data printed on the equipment nameplate would include manufacturer, model, and serialnumber and? - ANSWER-Stamp of approval from commissioning authority

How many BTU does it take to raise 10 lbs of steam from 40 to 41 degrees? - ANSWER-1 BTU When working on a boiler permits should be required? - ANSWER-For every shift

How many things do safety controls protect against? - ANSWER-Over pressure Over HeatingFire side explosions