DC BOILER 1ST UPDATD EXAM SCRIPT QUESTIONS AND
ANSWERS GRADED A+
✔✔Factor of Evaporation (FE) = - ✔✔= [Hs - (tfw-32)] ÷ 970.3
Hs = Enthalpy of steam
tfw = temperature of feed water
✔✔Latent Heat of Vaporization for Water - ✔✔970.3 Btu/lb
✔✔Latent Heat of Fusion for Water - ✔✔144 Btu/lb
✔✔1 Boiler Horsepower = x lbs of steam generator per hour - ✔✔34.5 lbs/hr
✔✔1 Boiler Horsepower = x Btu/hr - ✔✔33,475 Btu/hr
✔✔1 BHP = x ft² of heating surface (general) - ✔✔10 ft² heating surface
✔✔Volume of water increases by x percent when it flashes to steam - ✔✔x 1600
✔✔Thermal Efficiency (TE) = - ✔✔= Lbs Steam per hour [Hs -(fwt° -32)] ÷ Units of Fuel
per hour x Btu content per unit of fuel
Hs = Btu content of steam
fwt = feed water temperature
✔✔Developed Boiler Horsepower (DBHP) = - ✔✔= (Pounds of Steam per hour (Ws) x
FE) ÷ 34.5
Ws = Lbs of steam per hour
FE = Factor of Evaporation
✔✔Maximum Allowable Working Pressure (MAWP) - ✔✔= (TS x t x E) / FS x r
TS = Tensile Strength of steel
t = thickness of steel
E = Efficiency of joint
FS = Factor of Safety
r = radius of boiler drum
✔✔Bursting Pressure (BP) - ✔✔= (TS x t x E) / r
TS = Tensile Strength of steel
t = thickness of boiler plate
E = efficiency of joint
r = radius of boiler shell
✔✔Expansion (E) of Piping = - ✔✔= L x Cle x (T1 - T2) x 12
L = Length of pipe
, Cle = Coefficient of linear expansion
T = Temperature
✔✔Capacity of a Reciprocating Pump in gpm = - ✔✔= (L x A x N x E ) / 231
L = Length of stroke
A = Area of water piston
N = Number of strokes per minute
E = Pump Efficiency
231 = number of cubic inches per gallon of water
✔✔No. of cubic inches per gallon of water - ✔✔231 cu.in.
✔✔weight of 1 gallon of water - ✔✔8.33 lbs
✔✔weight of water (head) - ✔✔.433 psi / ft
2.31 ft = 1 psi
✔✔Fuel oil correction = - ✔✔1-[(Temp of fuel delivered - 60°) x .000345] x gallons of
fuel
✔✔Thermal Efficiency (TE) - ✔✔= Ws x [Hs -(fwt - 32)] / Wf x C
Ws = Weight of steam in lbs
Hs = Entalpy of steam
fwt = feed water temp.
Wf = Weight of fuel
C = Heat content per unit of fuel
✔✔Evaporation Rate (Where feedwater heat content of setam are constant) - ✔✔Ws ÷
Wf
Ws = Steam flow in lbs / hr
Wf = Fuel flow in lbs / hour or therms / hour
✔✔Specific Gravity of Mercury (Hg) - ✔✔13.57
✔✔equivalent psi of water of 1" of Mercury - ✔✔.491 psi
✔✔Atmospheric pressure in psi - ✔✔14.7 psi
✔✔Atmospheric pressure in in.Hg. - ✔✔29.29 in.HG
✔✔Lbs of air required to burn 1 lb of fuel - ✔✔15 lbs
✔✔% of oxygen in air - ✔✔21%
ANSWERS GRADED A+
✔✔Factor of Evaporation (FE) = - ✔✔= [Hs - (tfw-32)] ÷ 970.3
Hs = Enthalpy of steam
tfw = temperature of feed water
✔✔Latent Heat of Vaporization for Water - ✔✔970.3 Btu/lb
✔✔Latent Heat of Fusion for Water - ✔✔144 Btu/lb
✔✔1 Boiler Horsepower = x lbs of steam generator per hour - ✔✔34.5 lbs/hr
✔✔1 Boiler Horsepower = x Btu/hr - ✔✔33,475 Btu/hr
✔✔1 BHP = x ft² of heating surface (general) - ✔✔10 ft² heating surface
✔✔Volume of water increases by x percent when it flashes to steam - ✔✔x 1600
✔✔Thermal Efficiency (TE) = - ✔✔= Lbs Steam per hour [Hs -(fwt° -32)] ÷ Units of Fuel
per hour x Btu content per unit of fuel
Hs = Btu content of steam
fwt = feed water temperature
✔✔Developed Boiler Horsepower (DBHP) = - ✔✔= (Pounds of Steam per hour (Ws) x
FE) ÷ 34.5
Ws = Lbs of steam per hour
FE = Factor of Evaporation
✔✔Maximum Allowable Working Pressure (MAWP) - ✔✔= (TS x t x E) / FS x r
TS = Tensile Strength of steel
t = thickness of steel
E = Efficiency of joint
FS = Factor of Safety
r = radius of boiler drum
✔✔Bursting Pressure (BP) - ✔✔= (TS x t x E) / r
TS = Tensile Strength of steel
t = thickness of boiler plate
E = efficiency of joint
r = radius of boiler shell
✔✔Expansion (E) of Piping = - ✔✔= L x Cle x (T1 - T2) x 12
L = Length of pipe
, Cle = Coefficient of linear expansion
T = Temperature
✔✔Capacity of a Reciprocating Pump in gpm = - ✔✔= (L x A x N x E ) / 231
L = Length of stroke
A = Area of water piston
N = Number of strokes per minute
E = Pump Efficiency
231 = number of cubic inches per gallon of water
✔✔No. of cubic inches per gallon of water - ✔✔231 cu.in.
✔✔weight of 1 gallon of water - ✔✔8.33 lbs
✔✔weight of water (head) - ✔✔.433 psi / ft
2.31 ft = 1 psi
✔✔Fuel oil correction = - ✔✔1-[(Temp of fuel delivered - 60°) x .000345] x gallons of
fuel
✔✔Thermal Efficiency (TE) - ✔✔= Ws x [Hs -(fwt - 32)] / Wf x C
Ws = Weight of steam in lbs
Hs = Entalpy of steam
fwt = feed water temp.
Wf = Weight of fuel
C = Heat content per unit of fuel
✔✔Evaporation Rate (Where feedwater heat content of setam are constant) - ✔✔Ws ÷
Wf
Ws = Steam flow in lbs / hr
Wf = Fuel flow in lbs / hour or therms / hour
✔✔Specific Gravity of Mercury (Hg) - ✔✔13.57
✔✔equivalent psi of water of 1" of Mercury - ✔✔.491 psi
✔✔Atmospheric pressure in psi - ✔✔14.7 psi
✔✔Atmospheric pressure in in.Hg. - ✔✔29.29 in.HG
✔✔Lbs of air required to burn 1 lb of fuel - ✔✔15 lbs
✔✔% of oxygen in air - ✔✔21%
