DC Boiler Exam Prep 2023 (Formulas and constants used for the DC 3rd
class boiler exam) QUESTIONS WITH COMPLETE SOLUTIONS
1. Area of a rectangle - (correct answer) -Length x Width
fi fi fi fi fi fi fi fi fi
2. Area of a Circle - (correct answer) -.7854 x Diameter²
fi fi fi fi fi fi fi fi fi
3. Volume of a Box - (correct answer) -Length x Width x Height
fi fi fi fi fi fi fi fi fi fi fi
4. Volume of a Cylinder - (correct answer) -.7854 x Diameter² x
fi fi fi fi fi fi fi fi fi fi
Length
fi
5. Circumference of a Circle - (correct answer) -π x Diameter fi fi fi fi fi fi fi fi fi
6. Unit of Force - (correct answer) -Pound (lb)
fi fi fi fi fi fi fi
7. Formula for Force - (correct answer) -Pressure ÷ Area fi fi fi fi fi fi fi fi
8. Unit of Work - (correct answer) -in-lb or ft-lb
fi fi fi fi fi fi fi fi
9. Formula for Work - (correct answer) -Force x Distance fi fi fi fi fi fi fi fi
10. Unit of Power - (correct answer) -ft-lb/min
fi fi fi fi fi fi
11. Formula for Power - (correct answer) -= Work ÷ Time fi fi fi fi fi fi fi fi fi fi
12. or (Force x Distance) ÷ Time
fi fi fi fi fi
13. Formula for Mechanical Horsepower - (correct answer) -= fi fi fi fi fi fi fi
Power ÷ 33,000 ft-lb/min
fi fi fi fi
14. Fahrenheit to Celsius - (correct answer) -°C = (°F - 32) ÷ 1.8 fi fi fi fi fi fi fi fi fi fi fi fi
15. Celsius to Fahrenheit - (correct answer) -°F = (1.8 x °C) - 32
fi fi fi fi fi fi fi fi fi fi fi fi
16. Fahrenheit to Rankine - (correct answer) -°R = °F + 460 fi fi fi fi fi fi fi fi fi fi
17. Celsius to Kelvin - (correct answer) -K = °C +273.15
fi fi fi fi fi fi fi fi fi
18. Charles' First Law - (correct answer) -Volume1 / Pressure1 =
fi fi fi fi fi fi fi fi fi
Volume2 / Pressure2
fi fi fi
19. Charles' Second Law - (correct answer) -Pressure1 / fi fi fi fi fi fi fi
Temperature1 = Pressure2 / Temperature2
fi fi fi fi fi
20. Boyle's Law - (correct answer) -Pressure1 x Volume1 =
fi fi fi fi fi fi fi fi
Pressure2 x Volume2
fi fi fi
21. General Gas Law - (correct answer) -(Pres1 x Vol1)/ Temp1 =
fi fi fi fi fi fi fi fi fi fi
(Pres2 x Vol2)/Temp2
fi fi fi
22. Formula for Levers - (correct answer) -Resistance x fi fi fi fi fi fi fi
DistanceR = Effort x DistanceE
fi fi fi fi fi
23. Formula for Inclined Planes - (correct answer) -Force x fi fi fi fi fi fi fi fi
Length = Resistance x Height
fi fi fi fi fi
24. Formula for Wheel & Axel - (correct answer) -Force x fi fi fi fi fi fi fi fi fi
1 / fifi
17
fifi
,
DC Boiler Exam Prep 2023 (Formulas and constants used for the DC 3rd
class boiler exam) QUESTIONS WITH COMPLETE SOLUTIONS
DistanceF = Resistance x DistanceR
fi fi fi fi fi
25. Torque - (correct answer) -Force x Radius fi fi fi fi fi fi
26. Safe Working Pressure of a Riveted Boiler (SWP) - (correct
fi fi fi fi fi fi fi fi fi
answer) -(Area of Staybolt x Stress Constant of Staybolt) ÷
fi fi fi fi fi fi fi fi fi fi
Area Covered by Staybolt or = (a x C) ÷ A
fi fi fi fi fi fi fi fi fi fi fi
27. Area Covered by Staybolt - (correct answer) -= Pitch x Pitch
fi fi fi fi fi fi fi fi fi fi
28. Longitudinal Stress - (correct answer) -(P x D x L) / 2t fi fi fi fi fi fi fi fi fi fi fi
29. P = Pressurefi fi
30. D = Diameter fi fi
31. L = Length fi fi
32. t = thickness of steel
fi fi fi fi
33. Boiler Heating Surface (tubes) = - (correct answer) -= C x L x fi fi fi fi fi fi fi fi fi fi fi fi
#
fi
34. C = Circumference of tubes
fi fi fi fi
35. L = Length of tubes
fi fi fi fi
36. # = Number of tubes
fi fi fi fi
37. HS = π x Diameter x Length x Number of Tubes
fi fi fi fi fi fi fi fi fi fi
38. Watts per Boiler Horsepower - (correct answer) -746 Watts fi fi fi fi fi fi fi fi
39. Horsepower formula - (correct answer) -= ft-lb/min ÷ 33000 fi fi fi fi fi fi fi fi
ft-lb/min
fi
40. ft-lb formula for a pump - (correct answer) -= gpm x 8.33 x
fi fi fi fi fi fi fi fi fi fi fi fi
head (ft)
fi fi
41. Factor of Evaporation (FE) = - (correct answer) -= [Hs - (tfw- fi fi fi fi fi fi fi fi fi fi fi
32)] ÷ 970.3
fi fi
42. Hs = Enthalpy of steam fi fi fi fi
43. tfw = temperature of feed water fi fi fi fi fi
44. Latent Heat of Vaporization for Water - (correct answer) - fi fi fi fi fi fi fi fi fi
970.3 Btu/lb fi
45. Latent Heat of Fusion for Water - (correct answer) -144 fi fi fi fi fi fi fi fi fi
Btu/lb
fi
46. 1 Boiler Horsepower = x lbs of steam generator per hour -
fi fi fi fi fi fi fi fi fi fi fi
(correct answer) -34.5 lbs/hr
fi fi fi fi
2 / fifi
17
fifi
,
DC Boiler Exam Prep 2023 (Formulas and constants used for the DC 3rd
class boiler exam) QUESTIONS WITH COMPLETE SOLUTIONS
47. 1 Boiler Horsepower = x Btu/hr - (correct answer) -33,475
fi fi fi fi fi fi fi fi fi
Btu/hr
fi
48. 1 BHP = x ft² of heating surface (general) - (correct answer)
fi fi fi fi fi fi fi fi fi fi fi
-10 ft² heating surface
fi fi fi fi
49. Volume of water increases by x percent when it flashes to fi fi fi fi fi fi fi fi fi fi
steam - (correct answer) -x 1600
fi fi fi fi fi fi
50. Thermal Efficiency (TE) = - (correct answer) -= Lbs Steam fi fi fi fi fi fi fi fi fi
per hour [Hs -(fwt° -32)] ÷ Units of Fuel per hour x Btu content
fi fi fi fi fi fi fi fi fi fi fi fi fi fi
per unit of fuel
fi fi fi fi
51. Hs = Btu content of steam fi fi fi fi fi
52. fwt = feed water temperature fi fi fi fi
53. Developed Boiler Horsepower (DBHP) = - (correct answer) - fi fi fi fi fi fi fi fi
= (Pounds of Steam per hour (Ws) x FE) ÷ 34.5
fi fi fi fi fi fi fi fi fi fi fi
54. Ws = Lbs of steam per hour fi fi fi fi fi fi
55. FE = Factor of Evaporation fi fi fi fi
56. Maximum Allowable Working Pressure (MAWP) - (correct fi fi fi fi fi fi
answer) -= (TS x t x E) / FS x r
fi fi fi fi fi fi fi fi fi fi fi
57. TS = Tensile Strength of steel
fi fi fi fi fi
58. t = thickness of steel
fi fi fi fi
59. E = Efficiency of jointfi fi fi fi
60. FS = Factor of Safety fi fi fi fi
61. r = radius of boiler drum
fi fi fi fi fi
62. Bursting Pressure (BP) - (correct answer) -= (TS x t x E) / r fi fi fi fi fi fi fi fi fi fi fi fi fi
63. TS = Tensile Strength of steel
fi fi fi fi fi
64. t = thickness of boiler plate
fi fi fi fi fi
65. E = efficiency of jointfi fi fi fi
66. r = radius of boiler shell
fi fi fi fi fi
67. Expansion (E) of Piping = - (correct answer) -= L x Cle x (T1 - fi fi fi fi fi fi fi fi fi fi fi fi fi fi
T2) x 12
fi fi fi
68. L = Length of pipe fi fi fi fi
69. Cle = Coefficient of linear expansion fi fi fi fi fi
70. T = Temperature fi fi
3 / fifi
17
fifi
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