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DC Boiler Exam Prep 2024-

questions with correct answers

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. 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. Charles' First Law - correct answer -Volume1 / Pressure1 = Volume2 / Pressure Charles' Second Law - correct answer -Pressure1 / Temperature1 = Pressure2 / Temperature Boyle's Law - correct answer -Pressure1 x Volume1 = Pressure2 x Volume General Gas Law - correct answer -(Pres1 x Vol1)/ Temp1 = (Pres2 x Vol2)/Temp 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. Hs = Enthalpy of steam tfw = temperature of feed water Latent Heat of Vaporization for Water - correct answer -970.3 Btu/lb Latent Heat of Fusion for Water - correct answer -144 Btu/lb 1 Boiler Horsepower = x lbs of steam generator per hour - correct answer -34.5 lbs/hr 1 Boiler Horsepower = x Btu/hr - correct answer -33,475 Btu/hr

1 BHP = x ft² of heating surface (general) - correct answer -10 ft² heating surface Volume of water increases by x percent when it flashes to steam - correct answer -x 1600 Thermal Efficiency (TE) = - correct 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) = - correct answer -= (Pounds of Steam per hour (Ws) x FE) ÷ 34. Ws = Lbs of steam per hour FE = Factor of Evaporation Maximum Allowable Working Pressure (MAWP) - correct 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) - correct 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 = - correct 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 = - correct answer -= (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 - correct answer -231 cu.in. weight of 1 gallon of water - correct answer -8.33 lbs weight of water (head) - correct answer -.433 psi / ft 2.31 ft = 1 psi Fuel oil correction = - correct answer -1-[(Temp of fuel delivered - 60°) x .000345] x gallons of fuel Thermal Efficiency (TE) - correct answer -= 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) - correct answer -Ws ÷ Wf Ws = Steam flow in lbs / hr Wf = Fuel flow in lbs / hour or therms / hour

Specific Gravity of Mercury (Hg) - correct answer -13. equivalent psi of water of 1" of Mercury - correct answer -.491 psi Atmospheric pressure in psi - correct answer -14.7 psi Atmospheric pressure in in.Hg. - correct answer -29.29 in.HG Lbs of air required to burn 1 lb of fuel - correct answer -15 lbs % of oxygen in air - correct answer -21% Lbs of air required to burn 1 lb of carbon - correct answer -11.53 lbs Percentage of condensate return (Rc) - correct answer -= [Mc-Fc)/(Mc - CC)] x 100 Mc = Make-up conductivity Fc = Feedwater conductivity Cc = Condensate conductivity Conversion factor for grains per gallon to parts per million - correct answer -17. Weight of column of mercury in psi = - correct answer -= 13.57 x .433 x Height Formula for the horsepower requirement for a pump = - correct answer -(Q x 8.33 x H x sp.gr. ) / 33, 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. Target pH for condensate = - correct answer -8. 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, #6 fuel oil contains approximately _____ Btu/gal - correct answer -155, 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 - 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 What effect does temperature and pressure have on the activity of oxygen entrained in boiler feedwater? - correct answer -Oxygen is less active with high temperatures and pressures Define titration - correct answer -A procedure of neutralizing an unknown solution with a reagent of a known quantity The three basic classifications of impurities found in natural water are? - correct answer -dissolved solids, dissolved gasses, suspended solids What is the condition in which boiler metal becomes too brittle because of crystalline cracking? - correct answer -Caustic embrittlement Temporary hardness of water can be reduced by ____ the water. - correct answer -heating The ____ layup method is used for long term boiler storage. - correct answer -Dry An anion is an atom with a ____ electrical charge? - correct answer -negative The order in which a sodium zeolite water softener regenerates is - correct answer -Backwash, brine, rinse A _____ test is a test that determines the concentration of a specific dissolved substance. - correct answer -Titration Hardness of water is the measurement in ppm of ____ and ____ in the water. - correct answer -Calcium, magnesium As water is heated, the solubility of oxygen_____. - correct answer -decreases

Natural water generally has a pH of ____ to ____. - correct answer -6.5 to 7. A ____ amine is injected into a boiler during operation to raise the pH of the condensate. - correct answer -Neutralizing Two testing instruments used to determine the quantity of dissolved iron in a water sample are the ____ and ____. - correct answer -Color wheel comparator and spectrophotometer ______ cause hardness particles in boiler water to precipitate as heavy sludge that is removed through the bottom blow. - correct answer -Phosphates _____ keeps the hardness in boiler water in solution so that it cannot settle out on the heating surfaces.

• correct answer -Chelants _______ in boiler water contributes to the formation of CO2. - correct answer -High Alkalinity Pits of holes in iron or steel caused by excessive oxygen are called ____. - correct answer -Tubercles Rusty water in the gauge glass is a sign of _____ - correct answer -acid corrosion Where does hard scale form in a firetube steam boiler? - correct answer -At the steam and water interface on the shell and on the outside of the tubes What instrument is used to determine the amount of heat in steam? - correct answer -Throttling calorimeter Priming occurs when ______. - correct answer -Water is carried over with the steam Discharge limits of a boiler blowdown tank are ______°F & _____ psi. - correct answer -150, 5

Superheater safety valves are set at a pressure ____ than the boiler drum safety valves. - correct answer -Lower A steam pressure gauge should have a range at least _____. - correct answer -1-1/2 times the safety valve setting In steam tables, heat in liquid (h) equals _____. - correct answer -Total heat (hg) - latent heat (Hfs) Equation for determining theoretical water HP of a centrifugal pump - correct answer -= (Feet of Head x Pounds water/min) ÷ 33, One kW = ____ HP - correct answer -1. The minimum size connection between the gauge glass and water column is ____. - correct answer -1" Too little excess air can cause _____. - correct answer -Smoky fire A(n) _____ test is performed on a boiler to check the operation of the low water fuel cutoff by allowing the water level in the boiler to drop slowly. - correct answer -Evaporation A saybolt viscometer is used for _____. - correct answer -testing and grading of oils 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 A sudden increase in stack temperature without a corresponding increase n steam demand indicates what? - correct answer -a broken baffle What percentage of steam generated in a boiler is used for the steam atomizing burner? - correct answer -4%

What does a proximate analysis of coal determine? - correct answer -weight of moisture, fixed carbon, volatile matter, and ash content Try cocks are not effective above what steam pressure? - correct answer -250 psi What test determines if the safety valve(s) of a steam boiler have sufficient relieving capacity? - correct answer -accumulation test Carbon dioxide in flue gas is an indication of what? - correct answer -complete combustion An economizer is used to heat? - correct answer -feedwater The scanner must be mounted on the front of the burner so that it sights_____? - correct answer -both the pilot and the main flame How often should an evaporation test be performed to check the low water fuel cut off safety? - correct answer -monthly According to ASME Code, what must a boiler with more than 500 ft² of heating surface have? - correct answer -two or more safety valves To cut a boiler on line that is equipped with hand operated main steam stop valves, the steam pressure on the incoming boiler should be _______. - correct answer -slightly lower than the line pressure After replacing the gauge glass but before placing it in service, it is necessary to _____. - correct answer - crack open the steam valve and warm the glass What protects a steam pressure gauge from the high temperature of the steam? - correct answer -a siphon What is the minimum size of a manhole on a boiler? - correct answer -11" x 15"

The amount of excess air in gases of combustion is normally determined by the analysis of ____. - correct answer -O Equivalent evaporation = - correct answer -Ws x FE Ws = weight of steam in lbs/hr FE = Factor of evaporation What is the purpose of a bridge wall in the furnace of an HRT boiler? - correct answer -To direct the gases of combustion for better contact with the shell of the boiler. What are the two classifications of vertical firetube boilers? - correct answer -wet-top and dry-top What are the three types of heat transfer? - correct answer -Radiation, Convection, and Conduction The badge plate on a boiler will contain what information? - correct answer -Date built, ASME Symbol Stamp, Model Number, Heating Surface, Serial Number, MAWP, Burner Design Fuels, National Board of Boiler & Pressure Vessel Inspector's Registration Number, Burner Rating in Btu input What are the three types of stress - correct answer -Compression, Tension, and Shear Hopw are the shells of HRT boilers suspended? - correct answer -Lug-and-roller or overhead suspension What is the size of handholes? - correct answer -4" X 5" Theoretical natural draft - correct answer -D=0.52HP(1/T1-1/T2) D = Draft at base of chimney H = Height of chimney P = atmospheric pressure (normally 14.7 psia) T1 = Outside air temperature in °Rankin T2 = Stack temperature in °Rankin

One cubic foot of water is equal to ____ gallons - correct answer -7.49 gal