Formulas and Constants for DC Boiler Exam Preparation, Exams of Mathematics

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DC Boiler Exam Prep 2024 (Formulas And Constants Used For The Dc 3rd Class Boiler Exam) – Q&A Area of a rectangle - Correct answer -Length x Width Area of a Circle - Correct answer -.7854 x Diameter² Volume of a Box - Correct answer -Length x Width x Height Volume of a Cylinder - Correct answer -.7854 x Diameter² x Length Circumference of a Circle - Correct answer -π x Diameter Unit of Force - Correct answer -Pound (lb) Formula for Force - Correct answer -Pressure ÷ Area Unit of Work - Correct answer -in-lb or ft-lb Formula for Work - Correct answer -Force x Distance Unit of Power - Correct answer -ft-lb/min Formula for Power - Correct answer -= Work ÷ Time or (Force x Distance) ÷ Time Formula for Mechanical Horsepower - Correct answer -= Power ÷ 33,000 ft-lb/min Fahrenheit to Celsius - Correct answer -°C = (°F - 32) ÷ 1.8 Celsius to Fahrenheit - Correct answer -°F = (1.8 x °C) - 32 Fahrenheit to Rankine - Correct answer -°R = °F + 460 Celsius to Kelvin - Correct answer -K = °C +273.15 Charles' First Law - Correct answer -Volume1 / Pressure1 = Volume2 / Pressure2 Charles' Second Law - Correct answer -Pressure1 / Temperature1 = Pressure2 / Temperature2 Boyle's Law - Correct answer -Pressure1 x Volume1 = Pressure2 x Volume2 General Gas Law - Correct answer -(Pres1 x Vol1)/ Temp1 = (Pres2 x Vol2)/Temp2 Formula for Levers - Correct answer -Resistance x DistanceR = Effort x DistanceE Formula for Inclined Planes - Correct answer -Force x Length = Resistance x Height Formula for Wheel & Axel - Correct answer -Force x DistanceF = Resistance x DistanceR Torque - Correct answer -Force x Radius Safe Working Pressure of a Riveted Boiler (SWP) - Correct answer -(Area of Staybolt x Stress Constant of Staybolt) ÷ Area Covered by Staybolt or = (a x C) ÷ A Area Covered by Staybolt - Correct answer -= Pitch x Pitch Longitudinal Stress - Correct answer -(P x D x L) / 2t P = Pressure D = Diameter L = Length t = thickness of steel Boiler Heating Surface (tubes) = - Correct 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 - Correct answer -746 Watts Horsepower formula - Correct answer -= ft-lb/min ÷ 33000 ft-lb/min ft-lb formula for a pump - Correct answer -= gpm x 8.33 x head (ft) Factor of Evaporation (FE) = - Correct answer -= [Hs - (tfw-32)] ÷ 970.3 Hs = Enthalpy of steam tfw = temperature of feed water Latent Heat of Vaporization for Water - Correct answer -970.3 Btu/lb Formula for the horsepower requirement for a pump = - Correct answer -(Q x 8.33 x H x sp.gr. ) / 33,000 x n Q = flow rate in gpm H = total head sp.gr. = specific gravity of fluid being pumped n = Pump efficiency 1 lb of chemical to 1000 gallons of water = x ppm - Correct answer -120 ppm Target pH for boiler water - Correct answer -10.5 - 11.0 Target pH for condensate = - Correct answer -8.3 Target for Total Dissolved Solids (TDS) in steam boiler water - Correct answer -2000 - 2500 micromhos Target for Total Dissolved Solids (TDS) in a hot water boiler - Correct answer -3500 micromhos Water Horsepower = - Correct answer -= (Q x H) / 3960 Q = flow rate in gpm H = Head Flow rate of a pump (Q) = - Correct answer -= (3960 x WHP) / H Q = flow rate WHP = water horsepower H = Head Solve for total head for a pump = - Correct answer -= (3960 x WHP) / Q WHP = water horsepower Q = flow rate Solve for pump efficiency (n) = - Correct answer -= WHP / BHP WHP = water horsepower BHP = brake horsepower Pump brake horsepower (BHP) - Correct answer -= 100QH) / 3960n Q = flow rate H = Head n = pump efficiency Critical pressure and temperature of steam - Correct answer -3206 psia @ 705°F Above ____°F & ______ psi a hot water boiler is considered "high pressure" - Correct answer -250°F & 160 psi Max pressure for a fire tube boiler - Correct answer -250-350 psi Max horsepower of a fire tube boiler - Correct answer -750-1000 HP If a stay bolt is longer than 8", then it is considered a ____ - Correct answer -Through stay A 10°F rise in feed water temperature results in a ____ increase in efficiency - Correct answer -1% There are ___ gallons in a cubic foot of water - Correct answer -7.5 galons Pop type safety valves work up to ___ psi - Correct answer -600 psi During an accumulation test the pressure in the boiler cannot exceed the MAWP by more than ___% - Correct answer -6 % The target residual value for sodium sulfite is _____ - Correct answer -30-40 ppm A dearator stores how much feedwater? - Correct answer -20-30 minutes supply A single element feedwater heater responds to ____ - Correct answer -water level A two element feedwater heater responds to ____ - Correct answer -water level & steam flow A three element feedwater heater responds to ____ - Correct answer -water level, steam flow, & feedwater flow #2 fuel oil contains approximately ______ Btu/gal - Correct answer -141,000 #6 fuel oil contains approximately _____ Btu/gal - Correct answer -155,000 Fuel oil weighs approximately ___ lbs/gal - Correct answer -8 lbs Air is approximately ___% oxygen and ___ % nitrogen - Correct answer -21, 79 Formula for three phase kW - Correct answer -(E x I x PF x 1.732) ÷ 1000 Ohm's Law - Correct answer -E = I x R I Btu = ____ ft-lb - Correct answer -778 T /F - Dissolved Oxygen can be converted to free oxygen in a dearator - Correct answer -True T/F - The three major types of dearators are the tray, spray, and combination - Correct answer -True T/F - Boiler feedwater can be heated above 212°F in a vented heater - Correct answer - True T/F - Condensate will absorb oxygen and carbon dioxide as it cools - Correct answer - True A demineralizer is usually used with ____ pressure boilers - Correct answer -High When is bottom blowdown most effective? - Correct answer -At light loads When is continuous blowdown most effective? - Correct answer -During heavy steaming How can permanent hardness of water be reduced? - Correct answer -By the use of chemicals or distillation Where does dissolved CO2 in the boiler feedwater cause corrosion? - Correct answer - Condensate system Dissolved CO2 in boiler feedwater forms what compound that causes corrosion? - Correct answer -Carbonic acid Why add phosphates to boiler water? - Correct answer -Converts scale forming salts to non-adhering sludge Excess oxygen present bin the boiler water would be a direct indication of? - Correct answer -Improper operation of the dearating feedwater tank Cheleants do what when added to boiler water? - Correct answer -Convert calcium, magnesium, and iron to non-adhering sludge What two compounds are used as oxygen scavengers in boilers? - Correct answer - Sodium sulfite & Hydrazine Entrained oxygen in feedwater entering the boiler will cause ___? - Correct answer - Localized pitting What type of waterside deposits are removed by boiling out a boiler? - Correct answer - oil & grease What are the most common gases which become dissolved in the boiler water and will cause corrosion in the internals of the boiler? - Correct answer -Oxygen and Carbon Dioxide A(n) _____ analysis is used to determine the percentage of various elements contained in coal, including carbon, oxygen, nitrogen, hydrogen, sulphur, and ash. - Correct answer -ultimate A steam pressure gauge can be calibrated with a _____. - Correct answer -deadweight tester Electrostatic precipitators are used to ____. - Correct answer -remove flyash and soot from boiler exhaust The total pressure of a confined mixture of gases is the sum of the pressures of each of the gases in the mixture is known as ______. - Correct answer -Dalton's law Type L copper tubing is sized by - Correct answer -Inside diameter ACR tubing is sized by - Correct answer -Outside diameter When moisture is present in a refrigeration system it will react with the refrigerant and oil to form ____. - Correct answer -Acid The difference between system overshoot and system lag is called _______. - Correct answer -Temperature swing Typical superheat for an evaporator operating under normal conditions - Correct answer -8-12 degrees Water columns and gauge glasses should be blown down ____. - Correct answer -At least once per shift According to ASME code, the maximum size of the boiler bottom blowdown line is _____. - Correct answer -2-1/2" If the steam valve to the gauge glass is closed or the top line is clogged, the gauge glass will be ______. - Correct answer -Full Anthracite coal has a ________ content. - Correct answer -High fixed carbon An evaporation test should be performed _____ to check the low water fuel cut off control. - Correct answer -Monthly Boiler waterwalls should be blown down ______. - Correct answer -when the firebox is cool but the boiler has pressure Safety valves should not be tested unless the boiler pressure is at least ___% of the set pressure. - Correct answer -75% The Btu content of natural gas is ____ Btu per ____. - Correct answer -100,000; therm Fuel oil with a low flash point is - Correct answer -dangerous to handle The bypass damper on an air heater _____. - Correct answer -prevents corrosion at low rating by preventing the stack temperature from dropping below the dew point of the air. Steam at 100psi has a corresponding temperature of _____. - Correct answer -337.9°F According to ASME Code, a boiler pressure gauge should have a range of - Correct answer -1-1/2 - 2 times the safety valve setting A flash tank____ - Correct answer -Recovers low pressure steam In a balanced draft system, the pressure in the furnace is approximately ____. - Correct answer -atmospheric pressure or -0.1 iwc What compound is a major cause of air pollution and is caused by burning fuel oil? - Correct answer -Sulfur dioxide What coal has a high volatile content? - Correct answer -Bituminous What does a pyrometer measure? - Correct answer -Heat What type of flame scanner sensor senses visible light? - Correct answer -Photocell What type of flame scanner sensor is sensitive to infrared light? - Correct answer -Lead sulfide According to ASME Code, when warming up a boiler during cold plant startup, the boiler vent should remain open until the steam pressure reaches approximately ____ psi. - Correct answer -25 psi Where is the feedwater element located? - Correct answer -At the NOWL What should the boiler operator do if steam comes out of the bottom trycock when testing it? - Correct answer -Secure the fires to the boiler, allow the boiler to cool slowly, and notify the chief engineer On what type of coal stoker is an ignition arch used? - Correct answer -chain grate In which type of boiler are staybolts most commonly used? - Correct answer -firetube boiler Where does sludge and sediment from the mud drum get discharged to when blowing down a watertube boiler? - Correct answer -Blowdown tank A reciprocating pump is a ___ type pump. - Correct answer -positive displacement What type of test is used to test the density of smoke leaving a boiler? - Correct answer -Ringlemann test Water polluted with foreign matter or oil will cause an increase in ____. - Correct answer -surface tension What establishes flow through a superheater during boiler start up? - Correct answer - the superheater drain What is the lowest temperature at which fuel will flow called? - Correct answer -pour point The lowest temperature at which fuel oil will burn continuously is the_____. - Correct answer -fire point According to ASME Code how often should a boiler be blown down when no boiler water analysis is done? - Correct answer -every 24 hours Boiler CO2 readings of 12.5% over fire, 11.5% in the second pass, and 8% at the damper indicate____? - Correct answer -leaks through the boiler side wall How much pressure is applied to a boiler during a hydrostatic test? - Correct answer -1- 1/2 times the MAWP The size of the bottom blowdown lines can be reduced when ______. - Correct answer - the boiler has less than 100 ft² of heating surface What four things are required for complete combustion of fuel? - Correct answer - mixture, atomization, temperature, and time What compound when found in the flue gas is a sign of incomplete combustion? - Correct answer -Carbon Monoxide What device is used to check boiler combustion efficiency? - Correct answer -Orsat analyzer What type of valve is best used for throttling service? - Correct answer -Globe valve What is necessary to burn the volatile matter in coal more efficiently? - Correct answer - overfire air What is required to burn pulverized coal efficiently? - Correct answer -a high furnace temperature