DC 3rd Class Boiler Exam Prep: Essential Formulas and Constants for Success

DC 3rd Class Boiler Exam Prep: Essential Formulas and Constants for Success Length x Width - Area of a rectangle .7854 x Diameter² - Area of a Circle Length x Width x Height - Volume of a Box .7854 x Diameter² x Length - Volume of a Cylinder π x Diameter - Circumference of a Circle Pound (lb) - Unit of Force Pressure ÷ Area - Formula for Force in-lb or ft-lb - Unit of Work Force x Distance - Formula for Work ft-lb/min - Unit of Power = Work ÷ Time or (Force x Distance) ÷ Time - Formula for Power = Power ÷ 33,000 ft-lb/min - Formula for Mechanical Horsepower °C = (°F - 32) ÷ 1.8 - Fahrenheit to Celsius °F = (1.8 x °C) - 32 - Celsius to Fahrenheit °R = °F + 460 - Fahrenheit to Rankine K = °C +273.15 - Celsius to Kelvin Volume1 / Pressure1 = Volume2 / Pressure2 - Charles' First Law Pressure1 / Temperature1 = Pressure2 / Temperature2 - Charles' Second Law Pressure1 x Volume1 = Pressure2 x Volume2 - Boyle's Law (Pres1 x Vol1)/ Temp1 = (Pres2 x Vol2)/Temp2 - General Gas Law Resistance x DistanceR = Effort x DistanceE - Formula for Levers Force x Length = Resistance x Height - Formula for Inclined Planes Force x DistanceF = Resistance x DistanceR - Formula for Wheel & Axel Force x Radius - Torque (Area of Staybolt x Stress Constant of Staybolt) ÷ Area Covered by Staybolt or = (a x C) ÷ A - Safe Working Pressure of a Riveted Boiler (SWP) = Pitch x Pitch - Area Covered by Staybolt (P x D x L) / 2t P = Pressure D = Diameter L = Length t = thickness of steel - Longitudinal Stress = 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 - Boiler Heating Surface (tubes) = 746 Watts - Watts per Boiler Horsepower = ft-lb/min ÷ 33000 ft-lb/min - Horsepower formula = gpm x 8.33 x head (ft) - ft-lb formula for a pump = [Hs - (tfw-32)] ÷ 970.3 Hs = Enthalpy of steam tfw = temperature of feed water - Factor of Evaporation (FE) = 970.3 Btu/lb - Latent Heat of Vaporization for Water 144 Btu/lb - Latent Heat of Fusion for Water 34.5 lbs/hr - 1 Boiler Horsepower = x lbs of steam generator per hour 33,475 Btu/hr - 1 Boiler Horsepower = x Btu/hr 10 ft² heating surface - 1 BHP = x ft² of heating surface (general) x 1600 - Volume of water increases by x percent when it flashes to steam = 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 - Thermal Efficiency (TE) = = (Pounds of Steam per hour (Ws) x FE) ÷ 34.5 Ws = Lbs of steam per hour FE = Factor of Evaporation - Developed Boiler Horsepower (DBHP) = = (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 - Maximum Allowable Working Pressure (MAWP) = (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 - Bursting Pressure (BP) = L x Cle x (T1 - T2) x 12 L = Length of pipe Cle = Coefficient of linear expansion T = Temperature - Expansion (E) of Piping = = (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 - Capacity of a Reciprocating Pump in gpm = 231 . - No. of cubic inches per gallon of water 8.33 lbs - weight of 1 gallon of water .433 psi / ft 2.31 ft = 1 psi - weight of water (head) 1-[(Temp of fuel delivered - 60°) x .000345] x gallons of fuel - Fuel oil correction = = 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 - Thermal Efficiency (TE) Ws ÷ Wf Ws = Steam flow in lbs / hr Wf = Fuel flow in lbs / hour or therms / hour - Evaporation Rate (Where feedwater heat content of setam are constant) 13.57 - Specific Gravity of Mercury (Hg) .491 psi - equivalent psi of water of 1" of Mercury 14.7 psi - Atmospheric pressure in psi 29.29 in.HG - Atmospheric pressure in in.Hg. 15 lbs - Lbs of air required to burn 1 lb of fuel 21% - % of oxygen in air 11.53 lbs - Lbs of air required to burn 1 lb of carbon = [Mc-Fc)/(Mc - CC)] x 100 Mc = Make-up conductivity Fc = Feedwater conductivity Cc = Condensate conductivity - Percentage of condensate return (Rc) 17.1 - Conversion factor for grains per gallon to parts per million = 13.57 x .433 x Height - Weight of column of mercury in psi = (Q x 8.33 x H x . ) / 33,000 x n Q = flow rate in gpm H = total head . = specific gravity of fluid being pumped n = Pump efficiency - Formula for the horsepower requirement for a pump = 120 ppm - 1 lb of chemical to 1000 gallons of water = x ppm 10.5 - 11.0 - Target pH for boiler water 8.3 - Target pH for condensate = micromhos - Target for Total Dissolved Solids (TDS) in steam boiler water 3500 micromhos - Target for Total Dissolved Solids (TDS) in a hot water boiler = (Q x H) / 3960 Q = flow rate in gpm H = Head - Water Horsepower = = (3960 x WHP) / H Q = flow rate WHP = water horsepower H = Head - Flow rate of a pump (Q) = = (3960 x WHP) / Q WHP = water horsepower Q = flow rate - Solve for total head for a pump = = WHP / BHP WHP = water horsepower BHP = brake horsepower - Solve for pump efficiency (n) = = 100QH) / 3960n Q = flow rate H = Head n = pump efficiency - Pump brake horsepower (BHP) 3206 psia @ 705°F - Critical pressure and temperature of steam 250°F & 160 psi - Above ____°F & ______ psi a hot water boiler is considered "high pressure" 250-350 psi - Max pressure for a fire tube boiler 750-1000 HP - Max horsepower of a fire tube boiler Through stay - If a stay bolt is longer than 8", then it is considered a ____ 1% - A 10°F rise in feed water temperature results in a ____ increase in efficiency 7.5 galons - There are ___ gallons in a cubic foot of water 600 psi - Pop type safety valves work up to ___ psi 6 % - During an accumulation test the pressure in the boiler cannot exceed the MAWP by more than ___% 30-40 ppm - The target residual value for sodium sulfite is _____ 20-30 minutes supply - A dearator stores how much feedwater? water level - A single element feedwater heater responds to ____ water level & steam flow - A two element feedwater heater responds to ____ water level, steam flow, & feedwater flow - A three element feedwater heater responds to ____ 141,000 - #2 fuel oil contains approximately ______ Btu/gal 155,000 - #6 fuel oil contains approximately _____ Btu/gal 8 lbs - Fuel oil weighs approximately ___ lbs/gal 21, 79 - Air is approximately ___% oxygen and ___ % nitrogen (E x I x PF x 1.732) ÷ 1000 - Formula for three phase kW E = I x R - Ohm's Law 778 - I Btu = ____ ft-lb True - T /F - Dissolved Oxygen can be converted to free oxygen in a dearator True - T/F - The three major types of dearators are the tray, spray, and combination True - T/F - Boiler feedwater can be heated above 212°F in a vented heater True - T/F - Condensate will absorb oxygen and carbon dioxide as it cools High - A demineralizer is usually used with ____ pressure boilers At light loads - When is bottom blowdown most effective? During heavy steaming - When is continuous blowdown most effective? By the use of chemicals or distillation - How can permanent hardness of water be reduced? Condensate system - Where does dissolved CO2 in the boiler feedwater cause corrosion? Carbonic acid - Dissolved CO2 in boiler feedwater forms what compound that causes corrosion? Converts scale forming salts to non-adhering sludge - Why add phosphates to boiler water? Improper operation of the dearating feedwater tank - Excess oxygen present bin the boiler water would be a direct indication of? Convert calcium, magnesium, and iron to non-adhering sludge - Cheleants do what when added to boiler water? Sodium sulfite & Hydrazine - What two compounds are used as oxygen scavengers in boilers? Localized pitting - Entrained oxygen in feedwater entering the boiler will cause ___? oil & grease - What type of waterside deposits are removed by boiling out a boiler? Oxygen and Carbon Dioxide - What are the most common gases which become dissolved in the boiler water and will cause corrosion in the internals of the boiler? Oxygen is less active with high temperatures and pressures - What effect does temperature and pressure have on the activity of oxygen entrained in boiler feedwater? A procedure of neutralizing an unknown solution with a reagent of a known quantity - Define titration dissolved solids, dissolved gasses, suspended solids - The three basic classifications of impurities found in natural water are? Caustic embrittlement - What is the condition in which boiler metal becomes too brittle because of crystalline cracking? heating - Temporary hardness of water can be reduced by ____ the water. Dry - The ____ layup method is used for long term boiler storage. negative - An anion is an atom with a ____ electrical charge? Backwash, brine, rinse - The order in which a sodium zeolite water softener regenerates is Titration - A _____ test is a test that determines the concentration of a specific dissolved substance. Calcium, magnesium - Hardness of water is the measurement in ppm of ____ and ____ in the water. decreases - As water is heated, the solubility of oxygen_____. 6.5 to 7.5 - Natural water generally has a pH of ____ to ____. Neutralizing - A ____ amine is injected into a boiler during operation to raise the pH of the condensate. Color wheel comparator and spectrophotometer - Two testing instruments used to determine the quantity of dissolved iron in a water sample are the ____ and ____. Phosphates - ______ cause hardness particles in boiler water to precipitate as heavy sludge that is removed through the bottom blow. Chelants - _____ keeps the hardness in boiler water in solution so that it cannot settle out on the heating surfaces. High Alkalinity - _______ in boiler water contributes to the formation of CO2. Tubercles - Pits of holes in iron or steel caused by excessive oxygen are called ____. acid corrosion - Rusty water in the gauge glass is a sign of _____ At the steam and water interface on the shell and on the outside of the tubes - Where does hard scale form in a firetube steam boiler? Throttling calorimeter - What instrument is used to determine the amount of heat in steam? Water is carried over with the steam - Priming occurs when ______. 150, 5 - Discharge limits of a boiler blowdown tank are ______°F & _____ psi. Lower - Superheater safety valves are set at a pressure ____ than the boiler drum safety valves. 1-1/2 times the safety valve setting - A steam pressure gauge should have a range at least _____. Total heat (hg) - latent heat (Hfs) - In steam tables, heat in liquid (h) equals _____. = (Feet of Head x Pounds water/min) ÷ 33,000 - Equation for determining theoretical water HP of a centrifugal pump 1.34 - One kW = ____ HP 1" - The minimum size connection between the gauge glass and water column is ____. Smoky fire - Too little excess air can cause _____. Evaporation - 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. testing and grading of oils - A saybolt viscometer is used for _____. ultimate - A(n) _____ analysis is used to determine the percentage of various elements contained in coal, including carbon, oxygen, nitrogen, hydrogen, sulphur, and ash. deadweight tester - A steam pressure gauge can be calibrated with a _____. remove flyash and soot from boiler exhaust - Electrostatic precipitators are used to ____. Dalton's law - 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 ______. Inside diameter - Type L copper tubing is sized by Outside diameter - ACR tubing is sized by Acid - When moisture is present in a refrigeration system it will react with the refrigerant and oil to form ____. Temperature swing - The difference between system overshoot and system lag is called _______. 8-12 degrees - Typical superheat for an evaporator operating under normal conditions At least once per shift - Water columns and gauge glasses should be blown down ____. 2-1/2" - According to ASME code, the maximum size of the boiler bottom blowdown line is _____. Full - If the steam valve to the gauge glass is closed or the top line is clogged, the gauge glass will be ______. High fixed carbon - Anthracite coal has a ________ content. Monthly - An evaporation test should be performed _____ to check the low water fuel cut off control. when the firebox is cool but the boiler has pressure - Boiler waterwalls should be blown down ______. 75% - Safety valves should not be tested unless the boiler pressure is at least ___% of the set pressure. 100,000; therm - The Btu content of natural gas is ____ Btu per ____. dangerous to handle - Fuel oil with a low flash point is prevents corrosion at low rating by preventing the stack temperature from dropping below the dew point of the air. - The bypass damper on an air heater _____. 337.9°F - Steam at 100psi has a corresponding temperature of _____. 1-1/2 - 2 times the safety valve setting - According to ASME Code, a boiler pressure gauge should have a range of Recovers low pressure steam - A flash tank____ atmospheric pressure or -0.1 iwc - In a balanced draft system, the pressure in the furnace is approximately ____. Sulfur dioxide - What compound is a major cause of air pollution and is caused by burning fuel oil? Bituminous - What coal has a high volatile content? Heat - What does a pyrometer measure? Photocell - What type of flame scanner sensor senses visible light? Lead sulfide - What type of flame scanner sensor is sensitive to infrared light? 25 psi - 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. At the NOWL - Where is the feedwater element located? Secure the fires to the boiler, allow the boiler to cool slowly, and notify the chief engineer - What should the boiler operator do if steam comes out of the bottom trycock when testing it? chain grate - On what type of coal stoker is an ignition arch used? firetube boiler - In which type of boiler are staybolts most commonly used? Blowdown tank - Where does sludge and sediment from the mud drum get discharged to when blowing down a watertube boiler? positive displacement - A reciprocating pump is a ___ type pump. Ringlemann test - What type of test is used to test the density of smoke leaving a boiler? surface tension - Water polluted with foreign matter or oil will cause an increase in ____. the superheater drain - What establishes flow through a superheater during boiler start up? pour point - What is the lowest temperature at which fuel will flow called? fire point - The lowest temperature at which fuel oil will burn continuously is the_____. every 24 hours - According to ASME Code how often should a boiler be blown down when no boiler water analysis is done? leaks through the boiler side wall - Boiler CO2 readings of 12.5% over fire, 11.5% in the second pass, and 8% at the damper indicate____? 1-1/2 times the MAWP - How much pressure is applied to a boiler during a hydrostatic test? the boiler has less than 100 ft² of heating surface - The size of the bottom blowdown lines can be reduced when ______. mixture, atomization, temperature, and time - What four things are required for complete combustion of fuel? Carbon Monoxide - What compound when found in the flue gas is a sign of incomplete combustion? Orsat analyzer - What device is used to check boiler combustion efficiency? Globe valve - What type of valve is best used for throttling service? overfire air - What is necessary to burn the volatile matter in coal more efficiently? a high furnace temperature - What is required to burn pulverized coal efficiently? a broken baffle - A sudden increase in stack temperature without a corresponding increase n steam demand indicates what? 4% - What percentage of steam generated in a boiler is used for the steam atomizing burner? weight of moisture, fixed carbon, volatile matter, and ash content - What does a proximate analysis of coal determine? 250 psi - Try cocks are not effective above what steam pressure? accumulation test - What test determines if the safety valve(s) of a steam boiler have sufficient relieving capacity? complete combustion - Carbon dioxide in flue gas is an indication of what? feedwater - An economizer is used to heat? both the pilot and the main flame - The scanner must be mounted on the front of the burner so that it sights_____? monthly - How often should an evaporation test be performed to check the low water fuel cut off safety? two or more safety valves - According to ASME Code, what must a boiler with more than 500 ft² of heating surface have? slightly lower than the line pressure - 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 _______. crack open the steam valve and warm the glass - After replacing the gauge glass but before placing it in service, it is necessary to _____. a siphon - What protects a steam pressure gauge from the high temperature of the steam? 11" x 15" - What is the minimum size of a manhole on a boiler? O2 - The amount of excess air in gases of combustion is normally determined by the analysis of ____. Ws x FE Ws = weight of steam in lbs/hr FE = Factor of evaporation - Equivalent evaporation = To direct the gases of combustion for better contact with the shell of the boiler. - What is the purpose of a bridge wall in the furnace of an HRT boiler? wet-top and dry-top - What are the two classifications of vertical firetube boilers? Radiation, Convection, and Conduction - What are the three types of heat transfer? 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 - The badge plate on a boiler will contain what information? Compression, Tension, and Shear - What are the three types of stress Lug-and-roller or overhead suspension - Hopw are the shells of HRT boilers suspended? 4" X 5" - What is the size of handholes? 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 - Theoretical natural draft 7.49 gal - One cubic foot of water is equal to ____ gallons