DC Boiler Exam Prep//Formulas and constants used for the DC 3rd class boiler exam 2023//2024

DC Boiler Exam Prep//Formulas and constants used for the DC 3rd class boiler exam 2023//2024 Area of a rectangle - ANSWER Length x Width Area of a Circle - ANSWER .7854 x Diameter² Volume of a Box - ANSWER Length x Width x Height Volume of a Cylinder - ANSWER .7854 x Diameter² x Length Circumference of a Circle - ANSWER π x Diameter Unit of Force - ANSWER Pound (lb) Formula for Force - ANSWER Pressure ÷ Area Unit of Work - ANSWER in-lb or ft-lb Formula for Work - ANSWER Force x Distance Unit of Power - ANSWER ft-lb/min Formula for Power - ANSWER = Work ÷ Time or (Force x Distance) ÷ Time Formula for Mechanical Horsepower - ANSWER = Power ÷ 33,000 ft-lb/min Fahrenheit to Celsius - ANSWER °C = (°F - 32) ÷ 1.8 Celsius to Fahrenheit - ANSWER °F = (1.8 x °C) - 32 Fahrenheit to Rankine - ANSWER °R = °F + 460 Celsius to Kelvin - ANSWER K = °C +273.15 Charles' First Law - ANSWER Volume1 / Pressure1 = Volume2 / Pressure2 Charles' Second Law - ANSWER Pressure1 / Temperature1 = Pressure2 / Temperature2 Boyle's Law - ANSWER Pressure1 x Volume1 = Pressure2 x Volume2 General Gas Law - ANSWER (Pres1 x Vol1)/ Temp1 = (Pres2 x Vol2)/Temp2 Formula for Levers - ANSWER Resistance x DistanceR = Effort x DistanceE Formula for Inclined Planes - ANSWER Force x Length = Resistance x Height Formula for Wheel & Axel - ANSWER Force x DistanceF = Resistance x DistanceR Torque - ANSWER Force x Radius Safe Working Pressure of a Riveted Boiler (SWP) - ANSWER (Area of Staybolt x Stress Constant of Staybolt) ÷ Area Covered by Staybolt or = (a x C) ÷ A Area Covered by Staybolt - ANSWER = Pitch x Pitch Longitudinal Stress - ANSWER (P x D x L) / 2t P = Pressure D = Diameter L = Length t = thickness of steel Boiler Heating Surface (tubes) = - ANSWER = C x L x # C = Circumference of tubes L = Length of tubes # = Number of tubes HS = π x Diameter x Length x Number of Tubes Watts per Boiler Horsepower - ANSWER 746 Watts Horsepower formula - ANSWER = ft-lb/min ÷ 33000 ft-lb/min ft-lb formula for a pump - ANSWER = gpm x 8.33 x head (ft) Factor of Evaporation (FE) = - ANSWER = [Hs - (tfw-32)] ÷ 970.3 Hs = Enthalpy of steam tfw = temperature of feed water Latent Heat of Vaporization for Water - ANSWER 970.3 Btu/lb Latent Heat of Fusion for Water - ANSWER 144 Btu/lb 1 Boiler Horsepower = x lbs of steam generator per hour - ANSWER 34.5 lbs/hr 1 Boiler Horsepower = x Btu/hr - ANSWER 33,475 Btu/hr 1 BHP = x ft² of heating surface (general) - ANSWER 10 ft² heating surface Volume of water increases by x percent when it flashes to steam - ANSWER x 1600 Thermal Efficiency (TE) = - ANSWER = 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) = - ANSWER = (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) - ANSWER = (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) - ANSWER = (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 = - ANSWER = 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 = - ANSWER = (L x A x N x E ) / 231 L = Length of stroke