DIESEL FUELS & DIESEL FUEL SYSTEMS

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ContentsDiesel Fuels......................................................................... 1Common Diesel Fuel ......................................................... 2Diesel Fuel Grades ........................................................ 2Low Grade............................................................... 2High Grade .............................................................. 2American Society for Testing and Materials (ASTM) ...... 2Diesel Fuel Types ......................................................... 3Crude Oil................................................................. 3Residual Oil or Blended Heavy Fuel Oil (HFO)................ 3Distillate Fuel ........................................................... 3Marine Diesel Oil ...................................................... 3Aircraft Jet Fuels and Kerosene Type Fuels .................. 4Biodiesel.................................................................. 4Ultra Low Sulfur Diesel (ULSD) ................................... 4Diesel Fuel Characteristics ............................................. 5Diesel Fuel Selection......................................................... 6Diesel Fuel Systems ............................................................. 7Basic Fuel System ............................................................ 8MUI Fuel System ...................................................... 8MEUI Fuel System .................................................... 8HEUI Fuel System..................................................... 9Common Rail Fuel System ......................................... 9ACERT Technology ................................................. 10weindex.info

Diesel Fuel System Design Considerations ......................... 12Fuel Storage Systems ................................................. 12Main Fuel Tank....................................................... 12Auxiliary Fuel Tanks................................................ 13Fuel Head Limiting Tank .......................................... 16Base Mounted Tanks............................................... 16Fuel Tank Design Considerations .................................. 17Fuel Tank Sizing ..................................................... 17Fuel Tank Material .................................................. 17Fuel Tank Installation .............................................. 17Fuel Tank Drains..................................................... 17Fuel Tank Grounding ............................................... 18Fuel Tank Maintenance............................................ 18Fuel Transfer Systems................................................. 18Fuel Transfer Pumps ............................................... 20Fuel Piping Design Considerations................................. 21Fuel Supply Piping .................................................. 21Fuel Return Piping................................................... 22Purging ................................................................. 22Siphoning & Check Valves ....................................... 22Material................................................................. 22Sizing.................................................................... 23Routing ................................................................. 23Fuel Filtration Systems ................................................ 23Filter Micron Ratings ............................................... 24weindex.info

Primary Fuel Filter Element Specification .................... 25Duplex Fuel Filters .................................................. 25Water Separation.................................................... 26Miscellaneous Fuel System Considerations......................... 30Fuel Temperature ....................................................... 30Fuel Coolers............................................................... 30Fuel Heaters .............................................................. 31Partial Load Operation ................................................. 33Burning Used Crankcase Oil ......................................... 33Continuous Blending ............................................... 34Fuel Conservation Practices ............................................. 36Appendix 1 ....................................................................... 37Day Tank Sizing (When Day Tank Serves as a Heat Sink) .... 37Day Tank Calculations................................................. 37Day Tank Thermal Capacity Calculation ..................... 38Useful Fuel Formulas and Data ................................. 47Appendix 2 ....................................................................... 49Crude Oil Fuel................................................................ 49Pretreatment of Crude Oils........................................... 49Crude Oil Maintenance Intervals ................................... 51Crude Oil Settling Tanks.............................................. 51Reference Material ............................................................. 54weindex.info

ForewordThis section of the Application and Installation Guide generally describesDiesel Fuels and Diesel Fuel Systems for Caterpillar® engines listed on thecover of this section. Additional engine systems, components and dynamicsare addressed in other sections of this Application and Installation Guide.Engine-specific information and data are available from a variety ofsources. Refer to the Introduction section of this guide for additionalreferences.Systems and components described in this guide may not be available orapplicable for every engine.Information contained in this publication may be considered confidential.Discretion is recommended when distributing. Materials and specificationsare subject to change without notice.CAT, CATERPILLAR, their respective logos and “Caterpillar Yellow”, as wellas corporate and product identity used herein, are trademarks of Caterpillarand may not be used without permission.©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsDiesel FuelsDiesel fuel quality is an important factor in satisfactory engine life andperformance. Fuels must provide adequate combustion without producingexcess contaminates that can harm the engine. Additionally, fuel selectioninvolves economic and environmental considerations. The availability ofcertain grades of diesel fuels may be cost prohibitive or inappropriate forvarious applications. This Application and Installation Guide providesinformation on the various diesel fuel oil types and how they relate toCaterpillar engine installations.SECTION CONTENTSCommon Diesel Fuel............. 2• Diesel Fuel Grades• Diesel Fuel Types• Diesel Fuel CharacteristicsDiesel Fuel Selection .............6©2005 Caterpillar®All rights reserved. Page 1

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideCommon Diesel FuelDiesel Fuel GradesA variety of fuel oils, also knownas middle distillates, is marketed foruse in diesel engines. Theirproperties and performance dependupon the refining practices employedand the nature of the crude oils fromwhich they are produced. Becauseof constituents in the oil, somecrude oils are naturally suited forrefinement into high-grade fuelswhile others are best used for lowergradefuels. Similarly, high-gradefuels, low-grade fuels and thevarious grades between themprovide choices for the most suitablefuel for any given installation.Note: The use of very high-grade orvery low-grade fuel oils oftenrequires modification to the fuelsystem and special consideration ofadditional costs that may beencountered. Contact yourCaterpillar dealer for informationregarding the use of these fueltypes.Low GradeLow-grade fuels produce a higherheat value which translates intomore engine power, but they alsoproduce more contaminates thatcould negatively impact engine-life.Additionally, the use of low-gradefuel oil in diesel engines oftenproduces darker exhaust and a morepronounced odor. These attributesmay be objectionable in hospital,office, commercial or urban settingsand require the use of a higher-gradefuel.Page 2The high sulfur content oftenfound in low-grade fuels causescorrosion, wear and deposits in theengine. Fuels that are not volatileenough or don’t ignite rapidly mayleave harmful deposits in the engineand may cause poor starting orrunning under adverse operatingconditions. The use of low-gradefuels may require the use of highpriced, higher detergent lubricatingoils and more frequent oil changes toyield appropriate performance andengine life.High GradeHigh-grade fuels burn cleaner, buthave a lower heat value, whichyields slightly less power. Aviationjet fuels and kerosene are consideredhigh-grade fuels and seldomcontribute to the formation ofharmful engine deposits andcorrosion. Other attributes of highgradefuels include the benefits offaster engine starting and lessfrequent overhauls, and thedrawback of reduced lubricity.American Society for Testing andMaterials (ASTM)Due to the different engineapplications, designs and sizes,standards for the limits of fuelproperties have been set by theAmerican Society for Testing andMaterials (ASTM). Utilizing thecorrect fuel for the engine willminimize wear of the injectionsystem, allowing easier starting andimprove component service life.Experience has proven thatdistillate fuels meeting basic©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systemsspecifications will result in optimumengine performance and durability.Depending on fuel costs andavailability, the proper use ofalternative fuels such as crude oil,blended oil or residual oil can alsoprovide cost competitive engineoperation.Diesel Fuel TypesCrude OilThe term crude oil is used todescribe petroleum-based oils/fuelsthat are not yet refined. They areessentially in the same state aswhen they were pumped from theearth.Certain types of crude oils can beburned in Caterpillar Engines. Insome cases, crude oil is a practicaland economical fuel for dieselengines. Crude oils are evaluatedindividually and special equipmentmay be needed to condition the fuel.Minimum guidelines have beenestablished to determine thesuitability of crude oils as shown inAppendix 2.Residual Oil or Blended Heavy FuelOil (HFO)Residual fuel (which resembles tarand contains abrasive and corrosivesubstances) is composed of theremaining elements from crude oilafter the crude has been refined intodiesel fuel, gasoline, or lubricatingoil.After the more desirable productshave been refined, residual fuel canbe combined or diluted with a lighterfuel to produce a mixture that canflow. This mixture is called blendedor heavy fuel. Heavy fuels tend tocreate more combustion chamberdeposit formations which can causeincreased cylinder and ring wear.Blending may improve fuel density;however, adding alcohol (ethanol,methanol) or gasoline causes anexplosive atmosphere in the tankand is not recommended.Caterpillar 3600 diesel engines, ingeneral EPG applications only, canbe modified to run on blended fuels,but extreme PREVENTIVEMEASURES MUST BE TAKEN,including following a thoroughmaintenance program and use ofhigh quality fuel treatmentequipment. For any otherapplications including marine,petroleum, industrial, etc. thatrequire the burning of blended fuels,MAK Engines should be considered.Blended fuel can lower fuel cost,but there are often significant tradeoffs.Fuel price must be weighedagainst the following.• Fuel containment effects• Reduced engine componentlife• Higher maintenance andpersonnel costs• Reduced warrantyDistillate FuelDistillate fuels are refined fromcrude oil and are commonly referredto as diesel fuel, furnace oil, gas oil,or kerosene.Marine Diesel OilMany different names are used formarine diesel fuels, which can oftencause a misunderstanding. Fourtypes of marine diesel fuel aregenerally recognized and available at©2005 Caterpillar®All rights reserved. Page 3

Diesel Fuels & Diesel Fuel SystemsApplication and Installation Guidebunkering ports around the world.However, not all of the types areavailable at every station.Gas OilThis is a light distillate fuel whichdoes not contain any residual fuel.Gas oil is approximately ASTM No. 1diesel fuel.Marine DieselThis is a distillate fuel that boils ata higher temperature than gas oil.The fuel varies from ASTM No. 2diesel fuel to ASTM No. 4 dieselfuel. The composition can varywithin the following range: ASTMNo. 2 diesel fuel, No. 2 that iscontaminated with heavier fuel inthe bottom of the tanker, and No. 2that is blended with as much as 20% residual fuel.Blended Fuel OilThis is a blend of distillate andresidual fuel. This fuel is blended tothe viscosity that is requested by theoperator or the engine manufacturer.Blended fuel is not recommended foruse in Caterpillar engines that areconfigured to use distillate fuel.Residual FuelThis is residue from the distillationof crude oil in a refinery. DO NOTuse residual fuel in Caterpillarengines that are configured to usedistillate fuel.Aircraft Jet Fuels and Kerosene TypeFuelsAircraft jet fuels and kerosene typefuels may be used as a diesel enginefuel provided they meet acceptablelimits. Adequate viscosity,particularly with kerosene type fuelsis a major concern. For Caterpillarengine fuel systems, a minimumviscosity of 1.4 cSt at 38°C(100°F) is required at the enginetransfer pump to properly lubricatefuel system components. Kerosenetype fuels have lower energycontent than diesel fuels andtherefore will produce less peakpower output and/or will requiremore fuel volume to do anequivalent amount of work.BiodieselBiodiesel is a fuel that can be madefrom a variety of sources. Soybeanoil and rapeseed oil are the primarysources, but alternate base stocksmay include animal tallow, wastecooking oil, or a variety of otherfeedstocks.In original forms, these oils are notsuitable for use as a fuel incompression engines; they must firstbe esterified. Without esterification,these oils will gel in the crankcaseand the fuel tank.Ultra Low Sulfur Diesel (ULSD)Ultra low sulfur diesel representsdistillate fuels with ≤15 ppm sulfur.It has been developed to reduceparticulate engine emissions.Page 4©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsDiesel Fuel CharacteristicsThe following informationdescribes the basic fuelcharacteristics and their relation toengine performance.• Cetane Number: Index ofignition quality determined bycomparing with fuels used asstandards for high and lowcetane numbers. The higherthe cetane number is theshorter the ignition delayperiod which affects warmup,combustion, cold start andexhaust smoke density.• Sulfur: Sulfur is an elementthat occurs naturally in allcrude oils, and when burnedin the combustion chamber,can form oxides of sulfur.These can react with watervapor to create sulfuric acid,which can cause severeengine damage. High sulfurcontent requires usage of highTotal Base Number (TBN) oilsor shortening of the oil changeperiods.• Gravity: An index of weight ofa measured volume of fuel.Lower American PetroleumInstitute (API) ratings indicateheavier fuel containing greaterheat content.• Viscosity: A time measure toresistance of flow. Highviscosities cause poor fuelatomization therebydecreasing combustionefficiency. Low viscosity maynot provide adequatelubrication to fuel systemcomponents.• Distillation: This involvesheating crude to relativelyhigh temperatures. Vapordrawn at various temperaturesproduce fuels of differenttypes. Lighter fuels, such asgasoline, are drawn off firstand heavier fuels last. It hasan influence on viscosity ofthe fuel and the BTU content,which affects exhaust andsmoke, starting and poweroutput.• Flash Point: Lowesttemperature at which fuel willgive off sufficient vapor toignite when flame is applied.• Pour Point: Is the temperaturewhich is 3°C (5°F) above thetemperature where the fueljust fails to flow or turnssolid.• Cloud Point: The temperatureat which a cloud or a hazeappears in the fuel. This willhappen when the temperaturefalls below the melting pointof waxes or paraffins thatoccur naturally in petroleumproducts.• Water and Sediment:Percentage by volume ofwater and foreign materialremoved by centrifuging.• Carbon Residue: Percentageby weight of dry carbonremaining when fuel is burneduntil no liquid remains.• Ash: Percentage by weight ofdirt, dust, sand, and otherforeign matter remaining aftercombustion.©2005 Caterpillar®All rights reserved. Page 5

Diesel Fuels & Diesel Fuel SystemsApplication and Installation Guide• Corrosion: A polished copperstrip is immersed in fuel forthree hours at 50°C (122°F).Fuel imparting more thanslight discoloration is rejected.Diesel Fuel SelectionThe fuels recommended for use inCaterpillar diesel engines arenormally No. 2-D diesel fuel and No.2 fuel oil, although No. 1 grades arealso acceptable. Table 1 lists theworldwide fuel standards whichmeet Caterpillar requirements.Standard Name DescriptionASTMD975No. 1-D & No. 2-DDiesel Fuel OilsAmericanASTM No. 1 & No. 2 FuelD396OilsASTMD2880No. 1-GT & No. 2-GTGas Turbine FuelsBritishClasses A1, A2 & B2BS 2869Engine FuelsClasses C2 & D BurnerBS 2869FuelsDINWest 51601Diesel FuelGerman DIN51603Heating Oil ElAustralianAS Automotive Diesel3570FuelJapaneseJIS Types 1 (spl), 1, 2, 3,K2204 & 3 (spl) Gas OilDF-1, DF-2 Conus &W-F-DF-20 Conus Diesel800CFuelU.S.GovernmentU.S.MilitaryW-F-815CMIL-L-16884GFS-1 & FS-2 BurnerFuel OilMarine OilTable 1Table 2 lists acceptable aircraft jetfuels and kerosene type fuels.NameASTM D1655-80MIL-T-5624LMILT-T-83133BDescriptionAviation Turbine Fuel(JET A-1)Aviation Turbine Fuel(JP-5)(NATO Code No. F-44)Aviation Turbine Fuel(JP-8)(NATO Code No. F-34)Table 2Page 6©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsDiesel Fuel SystemsThe fuel system on a diesel engine is a highly specialized set ofcomponents which must deliver the correct amount of fuel to the cylinder atthe precise moment it is needed. A well-designed fuel system enables theengine to produce maximum power at maximum efficiency with a minimumof exhaust emissions.Today’s diesel injectors must develop very high injection pressures tofunction with modern high compression ratio engine designs. They must alsocontrol the start and duration of injection within milliseconds to perform atthe level demanded by engine customers. These precision injectors require anadequate supply of clean, stable fuel for proper operation. This requirementin turn demands careful attention to the fuel storage and handling systemsspecified for each installation.This section discusses the various fuel systems available on currentCaterpillar diesel engines, details the numerous fuel storage and handlingsystem options available for diesel fuels, and outlines the advantages,disadvantages, and special considerations which accompany each system.Diesel Engine Fuel System Descriptions/ComponentsCaterpillar diesel engines are all furnished with a fuel system based on aconventional design, utilizing unit injectors, but with differing means ofinjector actuation and control.The following sections briefly describe the basic fuel system and the threetypes of injector control systems currently in use.SECTION CONTENTSBasic Fuel System................ 8• MUI Fuel System• MEUI Fuel System• HEUI Fuel System• Common Rail Fuel System• ACERT TechnologyDesign Considerations .........12• Fuel Storage Systems• Fuel Tank DesignConsiderations• Fuel Transfer Systems• Fuel Piping DesignConsiderations• Fuel Filtration SystemsMiscellaneousConsiderations ...................30• Fuel Temperature• Fuel Coolers• Fuel Heaters• Burning Used Crankcase OilFuel ConsumptionPractices ...........................36©2005 Caterpillar®All rights reserved. Page 7

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideBasic Fuel SystemThe basic fuel system, common toall Caterpillar diesel engines, includesan engine driven fuel transfer pump,a secondary fuel filter, unit fuelinjectors and a fuel pressureregulator. Optional Caterpillarsupplied fuel system componentsinclude flexible hoses, a manual fuelpriming pump, and a duplex primaryfuel strainer. A basic fuel systemschematic is shown in Figure 1.The engine driven transfer pumpdelivers fuel to the unit injectors viathe secondary fuel filter. The pumpis equipped with a pump-mountedsafety valve and the fuel flow atrated rpm is listed in the technicaldata and varies with engine speed.The unit injector, eithermechanically or hydraulicallyactuated, combines the functions ofpumping, metering and injecting intoa single unit. It is located near thecenter of the combustion chamber ineach cylinder head, between therocker arms. External manifoldssupply fuel from the transfer pumpto the injectors, eliminating the needfor high pressure fuel lines. Fuelcontinuously circulates through theinjectors, and the excess fuel that isnot used for combustion cools theinjectors and is returned to the fueltank via the pressure regulatingvalve. This excess fuel also aids inthe purging of air from the system.The fuel delivery pressure to theinjectors is controlled by a pressureregulating valve. The pressureregulator must be adjusted at theinstallation site in order to providePage 8the proper fuel pressure to theinjectors.The manual fuel priming pump isrecommended if no electrical primingpump is available. The manual pumphelps to bleed air from the fuelpiping before initial engine operationand following engine maintenancesuch as filter element changes andinjector replacement.Caterpillar also recommends theuse of a duplex primary fuel filterprior to the engine driven fueltransfer pump. This filter is availablefrom Caterpillar via custom quote.When used, the duplex primary fuelfilter is installed, remotely from theengine, in the fuel transfer pumpsuction piping.MUI Fuel SystemThe Mechanically actuated andcontrolled Unit Injectors (MUI) usethe engine camshaft and push rodsto generate fuel injection pressure,and a mechanical linkage system tocontrol the amount of fuel injectedinto the cylinders. The mechanicallinkage system connects thegovernor to the fuel rack, whichallows the fuel rate to the engine tobe controlled in relation to thevarying engine loads.MEUI Fuel SystemThe Mechanically actuatedElectronically controlled UnitInjectors (MEUI), formerly known asElectronic Unit Injectors (EUI), alsouse the engine camshaft and pushrods to generate fuel injectionpressure, but use an Electronic©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsControl Module (ECM) to control theamount of fuel injected into thecylinders. A solenoid on eachinjector receives voltage signals fromthe ECM to become energized. Theinjectors will inject fuel only whilethe injector solenoid is energized.The ECM controls the amount offuel that is injected by varying thesignals that are sent to the injectors.By controlling the timing and theduration of the voltage signal, theECM can control injection timing andthe amount of fuel that is injected.HEUI Fuel SystemThe Hydraulically actuatedElectronically controlled UnitInjectors (HEUI) use a hydraulicpump and engine oil to generate fuelinjection pressure, and an ECM tocontrol the pressure and amount offuel injected into the cylinders.The operation of the HEUI fuelsystem is completely different fromany other type of fuel system that isactuated mechanically. The HEUIfuel system is completely free ofadjustment. Changes in performanceare made by installing differentsoftware in the ECM.Common Rail Fuel SystemUnlike the MEUI fuel system, in acommon rail fuel system injectionpressure is created external to theunit injectors in a high-pressure fuelpump which is driven off the engine.The pump pressurizes a highpressurefuel manifold that runsalong both sides of the enginefeeding high pressure fuel to theinjectors. The electronic fuelinjectors at each cylinder control thedelivery and timing of the fuelinjection(s). Similar to some othersystems, the common rail fuelsystem has capability of multipleinjections for a given combustionevent.The main components of acommon rail system include thehigh-pressure pump, the highpressurelines and rail system, andthe injectors. The low-pressure fuelsystem utilizes similar componentsto the unit injector fuel system. SeeFigure 2 for a schematic of thecommon rail fuel system.The common rail fuel system doesnot continually circulate fuel throughthe entire system like the unitinjector fuel system. Instead, smallamounts of fuel are bypassed duringthe injection event. Due to the veryhigh pressure in the fuel manifold,more heat is put into the fuel thanon previous systems. Because of theadditional heat added to the fuel, itis critical that the fuel inlettemperature is maintained withinguidelines provided for the enginemodel. Recommended, andsometimes required, is the use of afuel cooler to maintain theappropriate inlet fuel temperature.Otherwise, the overheated fuel willhave very low viscosity and filmstrength which makes the fuelsystem components, especially theinjectors, more susceptible todamage from fuel contaminants andwear, hence the importance ofproper filtration practices oncommon rail engines.©2005 Caterpillar®All rights reserved. Page 9

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideACERT TechnologyCaterpillar ACERT Technologyimproves diesel engine performance.This technology provides precisecontrol over a range of combustionvariables, which can be regulated toproduce higher performance withfewer emissions. This newtechnology works with the MEUI,HEUI and Common Rail fuelsystems.Fuel System SchematicFigure 1Page 10©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsCommon Rail System SchematicFigure 2©2005 Caterpillar®All rights reserved. Page 11

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideDiesel Fuel System Design ConsiderationsDiesel fuel supply systems mustensure continuous and clean supplyof fuel to the engine’s fuel system.The recommended diesel fuel supplysystem typically has three majorcomponents: a fuel storage system,a fuel transfer system and a fuelfiltration system. The threecomponent systems provide cleanoperating fuel to the engine.Fuel Storage SystemsBulk fuel is usually stored in largemain storage tanks and transferredto smaller auxiliary tanks (servicetanks or day tanks) near engines byelectric motor-driven pumps asshown in Figure 3.If auxiliary tanks are notnecessary, the main fuel tank mustprovide a ready fuel supply to theengine-mounted transfer pump.Main Fuel TankThe main fuel tank represents theprimary fuel reservoir in allapplications, and must haveadequate capacity for the intendedapplication. Rule of thumb for tanksize is to find the fuel consumptionrate at 100% load factor (dependingon application: Prime, stand-by etc.)and multiply it with the number ofhours between refills. Fuelconsumption rates are shown on theEngine Technical Data Sheets for thespecific engine. Additionally, 10%should be added to the result; 5%for expansion at the top of the tank,and 5% for sediment settlements atthe bottom.Example:A power plant with one (1) 3516Bdiesel generator set, rated for 1145bkW (1560 bhp) at 100% load. Thefuel rate for the engine is 284 L/hr(75 G/hr) as found in TMI.The time between tank refills isbased on weekly fuel tanker truckdeliveries, so refill time is 168 hours.Solution:Tank vol. = 284 x 168 x 1.1 = 52,583 LTank vol. = 75 x 168 x 1.1 = 12,600 galPage 12©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsInstallation Example with Main and Auxiliary Fuel TanksFigure 3Auxiliary Fuel TanksAuxiliary fuel tanks, service tanksand day tanks are secondary fueltanks located between the main fueltank and the engine. These tanks arerequired in the following situations.• The main fuel tank is locatedon the same level but morethan 15 m (50 ft) away.• The main fuel tank is located3.7 m (12 ft) or more belowthe engine.• The main fuel tank is locatedabove the engine fuelinjectors.Any of the above conditions cancause unsatisfactory engine startingand operation. The purpose of anauxiliary tank is to relieve the fuelpressure “head” from the fueltransfer pump and injectionequipment for efficient fuel flow.A manual fuel priming pump,offered as an attachment, or anelectric motor-driver boost pumpmay allow operation underconditions more severe than thosepreviously described; but wherestarting dependability is required,Caterpillar recommends the use ofan auxiliary fuel tank.Auxiliary tanks offer convenientand ready fuel storage whileproviding a settling reservoir forwater, sediment and sludge. Anexample of an auxiliary fuel tank isshown in Figure 4.©2005 Caterpillar®All rights reserved. Page 13

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideTypical Auxiliary Fuel TankFigure 4Fuel Service Tank or Day TankAuxiliary tanks such as fuel servicetanks or day tanks can be quitesimple. It usually consists of a smallmetal tank, either floor or wallmounted, in the immediate vicinityof the engine. The tank is usuallysized to hold approximately eighthours of fuel, based on the engine’sfuel consumption rate at full load.Refilling can be accomplished bygravity, a hand pump, or with amotor-drive pump. Motor-drivepumps can be either manually orPage 14automatically controlled. Forconvenience and safety, automaticcontrol is usually employed using afloat-actuated, electric motor-drivepump. The refilling pump can bepositioned either at the auxiliary tankor at the main tank outlet. Theperformance capability of the pumpmust be considered duringplacement.Features of the auxiliary tank, asshown in Figure 5, should includethe following.©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systems• Fill line - Located above thehigh fuel level, with outletbaffled to prevent agitation ofsediment in the tank.• Delivery line - Located nearthe bottom but not so low asto pick up collected sedimentor condensation.• Return line - To carry excessfuel back to the auxiliary tank.Should have its outlet baffledfor the reason describedabove.• Overflow line - Allows excessfuel to return to the main tankin event of overfilling of theauxiliary tank.• Vent line - Allows air pressureto equalize as tank is drainedor filled (vent cap should belocated away from open flameor sparks).• Drain valve - Allows removalof condensate and sediment.• Sight glass or float-type gauge- Provides a positive check onfuel level.To prevent damage to the fuelfilter housings, the return line shouldhave no valves or restrictions toallow dangerous pressure buildups.Flexible rubber hoses, used as fuelreturn lines, should be supported toprevent closing off over time due toweight of the hose and fuel. Hardfuel lines prevent this problem, but aflexible connection is still required toisolate vibration between the lineand the tank.A nonflammable tank mounting willmaximize fire protection.The overflow line should be atleast two pipe sizes larger than thefill line. To simplify enginemaintenance, a shut-off valve in thesupply line is useful.The delivery line, carrying the fuelto the engine-mounted fuel transferpump, and the return line, carryingexcess fuel back to the tank, shouldbe no smaller in size than therespective fittings on the engine.Larger fuel supply and return linesensure adequate flow if the fuel tanksupplies multiple engines over 9 m(30 ft.) away from the tank or whentemperatures are low. Consultgeneral dimension drawings for thesizes for each model.It is important that the fuel returnline is sloped down to the tank withno traps or obstructions in the line.If this is not done, the fuel system isprone to air-lock with consequenthard-starting.The auxiliary tank should belocated so that the level of the fuelwhen the tank is full is no higherthan the injection valves. Staticpressure would allow fuel to leakinto the combustion chambers in theevent of injection valve leakage. Thetank should be close enough to theengine so that the total suction liftto the transfer pump with the fuel atlow level, plus the line loss of thesupply line, is less than the fuelpump’s maximum suction liftcapability. This figure should beminimized for better starting. A floatvalve or solenoid valve in this typeof day tank regulates the fuel levelto keep it below the level of theinjectors.©2005 Caterpillar®All rights reserved. Page 15

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideTypical Fuel Head Limiting TankFigure 5Fuel Head Limiting TankIf overhead mounting of theservice tank or day tank isunavoidable, or if existing tanklocations in a re-power applicationdictate, then a small fuel headlimiting tank may be required. Thistank fulfills the same requirementsas the service tank or day tank, butstores a much smaller volume offuel. The fuel head limiting tank isinstalled between the engine and theservice tank or day tank. Its onlypurpose is to limit the head of fuelon the engine’s injection system.Base Mounted TanksBase mounted day tanks aresometimes used to provide aconvenient and close source of fuelwith adequate capacity for four toeight hours of operation. Whileminimizing the floor space neededfor fuel storage, the height of theengine will increase significantlywith this option designed to easemaintenance.Page 16©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsFuel returning to the main tankmay, because of its volume, aid withcooling, but returning to the daytank is permissible.Fuel Tank DesignConsiderationsFuel Tank SizingThe fuel tank is typically one of theleast expensive items in aninstallation, and it is wise to providetoo much, rather than too little,storage capacity. However, whilethe minimum required capacities offuel tanks can be estimated, asoutlined in the previous discussion offuel tanks, some applications mayneed to meet the requirements ofoutside organizations, such as theU.S. National Electrical Code (NEC)or National Fire ProtectionAssociation (NFPA).Fuel Tank MaterialFuel tanks made from low carbonrolled steel are best.CAUTION: Zinc, either in the form ofplating or as a major alloyingcomponent, should not be used withdiesel fuels. Zinc is unstable in thepresence of sulfur, particularly ifmoisture is present in the fuel. Thesludge formed by chemical action isextremely harmful to the engine’sinternal components.Fuel Tank InstallationLarge capacity storage tanks allowbulk purchases and minimize dirtcontamination. Maintaining full tanksreduces condensation, particularly iffuel is seldom used.Tanks may be above or belowground level, but high fuel levelgenerally should not exceed theengine injector’s height. Thisprevents possible fuel leakage intocylinders.Above ground tanks provideaccessibility, allowing for easydraining of impurities and reducingthe danger of ground watercontamination.Underground tanks allow the earthto work as an insulator, limitingradical temperature changes whichcan cause flow restrictions,condensation, and possible powerloss. Seasonal settlings are alsoavoided when burying the tankbelow frost line. In undergroundtanks, the water must be removedby pumping through a tube placeddown the fill pipe.Regulations governing theinstallation and maintenance of bothabove and below ground fuel tanksmay apply.Locate storage tank fill tubes forconvenience and safety of fillingoperations. Vents are necessary torelieve air pressure created by fillingand prevent vacuum as fuel isconsumed.Fuel Tank DrainsAll fuel tanks should have easilyaccessible drain connections. Waterand sediment that collects in thebottom of the tank must beeliminated regularly. Provide cleanoutopenings for periodical removalof sediment and trash that settlesout of fuel tanks.Well-designed tanks have largeenough clean-out openings so the©2005 Caterpillar®All rights reserved. Page 17

Diesel Fuels & Diesel Fuel SystemsApplication and Installation Guidelowest part of the fuel tank can beaccessed with cleaning equipment.Fuel Tank GroundingFuel tanks, both bulk and auxiliary,need to be grounded. This is toimprove personal safety and reducethe fire hazard of sparks dischargedfrom static electricity build-up duringrefueling operations.If the auxiliary tank is mounted tothe base of the engine, it will begrounded at the same time as theengine. If the fuel tank is placedaway from the engine, the tankmust be grounded separately.Fuel Tank MaintenanceFuel has a storage life ofapproximately one year. This periodmay vary widely depending uponinitial fuel quality, contaminant levelsand storage conditions.To remove water, scale andbacteria growth, periodic exchangeof fuel and filtering/treating isrecommended to extend fuel life.Water contamination of fuel duringlong-term storage provides a mediumfor bacterial growth, forming a darkslime which:• Plugs filters• Deposits on tank walls andpipes• Swells rubber products that itcontactsSulfur compounds are naturalantioxidants, so low sulfur fuels(0.05 percent by weight) degradequicker in storage.Diesel fuels oxidize and form gumsand varnishes which can plug fuelfilters and injectors.Page 18Because microorganism growthoccurs in the fuel/water layer, thetank should be designed to minimizethis interface, and water bottomsshould be drained regularly.Microbiocide additives, eitherwater or fuel soluble, can be addedto fresh fuel to inhibit microorganismgrowth. Consult your local fuelsupplier for recommended additives.In warm climates, large bulkstorage diesel fuel requires fullfiltering every six months to oneyear.Every two years the fuel should becompletely changed to removewater, scale, bacteria growth,oxidized gums/resins, and minimizefilter clogging due to fuel separationinto components such asasphaltenes.Fuel Transfer SystemsThe diesel engine fuel supply,delivery and governing systems aredesigned to deliver clean fuel in theprecise quantity and time needed toproduce the required engineperformance.All connection lines, valves andtanks should be thoroughly cleanedbefore making final connections tothe engine. The entire fuel systemexternal to the engine should beflushed prior to connection to engineand startup.Caterpillar supplies the engine witha transfer pump and the secondaryfilter. The customer must providethe primary filter and, if needed, anauxiliary transfer pump. The auxiliarytransfer pump is required when thedistance, vertically or horizontally,©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systemsbetween the day tank and engineexceeds the requirements discussedin Auxiliary Fuel Tanks. An exampleTypical Fuel Transfer System(Distillate Fuel Supply System)of a fuel transfer system is shown inFigure 6.Figure 6©2005 Caterpillar®All rights reserved. Page 19

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideFuel Transfer PumpsEngine DrivenCaterpillar engine-mounted transferpumps are positive displacementgear-type or piston-type pumps, witha limited prime and lift capability.The pump lifts the fuel bydisplacing air from the suction pipeto the discharge pipe. Low pressure(vacuum) develops in the suctionpipe and atmospheric pressure [101kPa (14.5 psi) at sea level] movesthe fuel into the vacuum. However,a perfect vacuum cannot bemaintained, and the maximum that apump can lift is about 5 m (17 ft).Caterpillar fuel pumps’ prime andlift capability is 3.7 m (12 ft), butpipe size, routing, and ambienttemperature will impact thiscapability.To determine if a pump canperform the required lift, thefollowing items must be considered.1. The vertical distance from thetank to the pump. The distanceshould be measured from theinlet pump port of the pump tothe bottom of the tank.2. Internal piping system lossesreduce the lifting capability. Thisis based primarily on the size andthe total length of the pipes, butalso includes the various fittingsand valves. As the temperaturegoes down the resistance goesup. The internal losses can beestimated using the PipingSystem Basic Information sectionof the Application & InstallationGuide.3. Elevation has a big impact onthe pump’s lifting capability. Asdescribed above the atmosphericpressure is helping the fuel intothe vacuum, but as the elevationgets greater, the atmosphericpressure decreases and theavailable lift will also decrease.Refer to Table 3.ElevationAtmospheric AvailablePressure Liftmeters feet kPa psi meters feet0 0 101.3 14.7 5.18 17.030.5 1000 98.0 14.2 4.87 16.061.0 2000 93.8 13.6 4.70 15.591.5 3000 90.3 13.1 4.57 15.0122.0 4000 86.9 12.6 4.40 14.5152.5 5000 83.4 12.1 4.26 14.0183.0 6000 80.7 11.7 4.10 13.5Table 3AuxiliaryAn auxiliary transfer pump isrequired when the service tank orday tank is located further away,horizontally or vertically, than theengine driven pump’s lift capability.Special considerations must begiven to the auxiliary transfer pumpwhen dealing with electronic enginesand the 3500 engine family. Thefuel flow for these engines isapproximately 2 to 3 times what isneeded for combustion. The auxiliarytransfer pump must be sized tomove the additional fuel.A primary filter must be installedbefore the auxiliary pump and asclose as possible to the tank.Page 20©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsIn many cases, the auxiliary pumpwill be driven by an electric motorand therefore needs a regulatorvalve so that the fuel flow canmatch the engine speed.Example:A power plant with one (1) 3516Bdiesel generator set, rated for 1145bkW (1560 bhp) at 100% load. Thefuel rate for the engine is 284 L/hr(75 G/hr) as found in TMI.The time between tank refills isbased on weekly fuel tanker truckdeliveries, so refill time is 168 hours.The fuel tank for this genset islocated 22 m (72.2 ft) horizontallyand 2.5 m (8.2 ft) vertically (below)from the engine. This situationexceeds the fuel systemrequirements discussed in AuxiliaryFuel Tanks, therefore, an auxiliarypump is needed.Solution:TMI indicates that the fuel flow atrated speed is 1260 L/hr (333 G/hr)@ 1200 rpm.The auxiliary transfer pumprequired for this sample installationmust be able to deliver fuel at 1260L/hr (333 G/hr) at a pressure of 34.5kPa (5 psi).EmergencyMany marine applications requirethe capability to connect anemergency fuel oil transfer pumpinto the engine’s fuel oil system.Caterpillar engines can be providedwith these optional connectionswhen necessary.This is a specific requirement ofmarine classification societies forseagoing single propulsion engineapplications. The purpose is toensure fuel oil supply in the event ofan engine fuel oil pump failure. Theemergency fuel oil pump allows thesingle propulsion engine to operateand the ship to reach port for enginerepairs.Guidelines for emergency fuel oilsystem operation:1. Keep pressure drops to aminimum by using short, lowrestrictionlines.2. Use a line size at least aslarge as the engine connectionpoint.3. Install a low-restrictionstrainer in front of the emergencyoil pump.4. Install a low-restriction checkvalve between the emergencypump discharge and the engineinlet connection.5. Use a pressure-limiting valvein the emergency system set atthe maximum oil pressure limit ofthe engine.6. TMI contains flow rates andpressure limits to fulfill minimumengine requirements for fullpower at rated speeds forCaterpillar engines.Fuel Piping DesignConsiderationsFuel Supply PipingUsing shutoff valves in the deliveryline may pull air into the systemduring shutdown and cause hardstarting. The engine control systemprovides adequate shutdownoptions, but, if a shutdown solenoidis specified in the supply line, it©2005 Caterpillar®All rights reserved. Page 21

Diesel Fuels & Diesel Fuel SystemsApplication and Installation Guideshould be timed to close after theengine stops rotating.PressureThe pressure measured in the fuelsupply line should be kept below thevalues shown in TMI.Fuel Return PipingFuel return piping should normallyenter the tank at the top and extenddownward, exiting above the fuellevel. Inlet and return lines should beseparated in the tank as far apart aspossible to allow fuel warmed in theengine to dissipate excess heat. Fueltanks can function as a radiator ofsorts, especially in engines that arenot equipped with a fuel cooler orengines that use fuel to cool theinjectors. Placing return lines andsuction lines as far apart as possibleprovides the most opportunity forcooling. Return line placement isparticularly important on smallertanks and day tanks where the fuelvolume is allowed to run down.The fuel return line is underpressure, although not as high as thesupply line.Note: Shut-off valves should not beused in fuel return lines. Engineoperation with the valve closed willcause damaging pressures.PressureEngine fuel pressure measured inthe fuel return line should be keptbelow 27 kPa (4 psi), except for the3300 engine family, which is 20 kPa(3 psi) and the 3600 family, which is350 kPa (51 psi). The location of theday tank and the design of the pipesshould accommodate theserequirements.PurgingPurging should take place both inthe supply and the return line.Siphoning & Check ValvesSiphoning can occur in full fuelpipes when the one end of the pipeis placed in the fuel and the otherend is below the level of fuel.Siphoning is a flow of fuel in thepipe without the help of pumps. Itcan occur in supply and return lines.Siphoning is most likely to occurafter a fuel line failure, which can bedue to corrosion, fire or a cut fromforeign objects or collision force.The consequences of fuel linesiphoning are fuel loss and thecreation of a fire hazard. If the fuelignites and the flow is not stopped,the fire will be more difficult toextinguish.The fuel supply line has a fueltransfer pump. To avoid siphoning,the pump must be equipped with acheck valve. This is in case thepump has been deactivated and thefuel supply line is breeched.MaterialBlack iron pipe is best suited fordiesel fuel lines. Copper pipe ortubing may be substituted in sizes of13.0 mm (0.5 in.) nominal pipe sizeor less. Valves and fittings may becast iron or bronze. Do not use brasscomponents; they contain zinc.CAUTION: Zinc, either in the form ofplating or as a major alloyingcomponent, should not be used withdiesel fuels. Zinc is unstable in thepresence of sulfur, particularly ifmoisture is present in the fuel. Thesludge formed by chemical action isPage 22©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systemsextremely harmful to the engine’sinternal components.Pipes, hoses and fittings must bemechanically strong and resistant todeterioration due to age orenvironmental conditions. They mustalso be airtight to avoid entry of airinto the suction side of the fuelsystem. A joint, which is leak-tightto fuel, can sometimes allow air toenter the fuel system, causingerratic running and loss of power.SizingSizing of pipes, hoses and fittingsmust be adequate to minimize flowloss.Sizing for a particular application isdetermined by the supply and returnline restrictions. This can beestimated with help from the PipingSystem Basic Information section ofthe Application & Installation Guide.The maximum allowable restrictionsare published in the TMI.Generally, the supply line carryingfuel to the fuel transfer pump andthe return line carrying excess fuelback to the tank should be nosmaller in size than the connectionfittings on the engine. In addition,the return line should be at least aslarge as the supply line.If the fuel tank supplies multipleengines over 9.14 m (30 ft) from thetank, or ambient temperatures arelow, larger fuel supply and returnlines should be considered to ensureadequate flow. The overflow linefrom the day tank (or, if no day tankis used, the engine fuel return line)should be one size larger than thesupply and return lines.RoutingFuel lines should be well routedand clipped with flexible hoseconnections where relative motion ispresent. Lines should be routedaway from hot surfaces, likemanifolds and turbochargers, toavoid fuel heating and potentialhazard if a fuel line should fail.Fuel lines should be routed toavoid formation of traps, which cancatch sediments, or pockets ofwater, which will freeze in coldweather.Whenever possible, route fuel linesdown low, so any potential leakagewill be confined to the fuel tankbase or floor space. Leaks fromoverhead fuel system componentsmay fall onto hot machinery,increasing the likelihood of firedanger.Route fuel lines to avoid crossingpaths and walkways. Protect fuellines from abrasion and damage.Whenever possible, route fuel linesso they are visible for leak checking.Fuel Filtration SystemsClean fuel that meets Caterpillarfuel recommendations providesoutstanding engine service life andperformance. The use of lesser fuelsis a compromise and the risk is theuser’s responsibility. Dirty fuel andfuels not meeting Caterpillar’sminimum specifications willadversely affect:• The perceived performance ofthe combustion system andfuel filters.©2005 Caterpillar®All rights reserved. Page 23

Diesel Fuels & Diesel Fuel SystemsApplication and Installation Guide• The service life of the fuelinjection system, valves,pistons, rings, liners andbearings.Even when fuel is handled verycarefully, foreign particles will findtheir way in during handling orstorage. Foreign particles could bepaint flakes, dust, sand, rust ormicrobiologic particles.Clean fuel is necessary fordependable engine performance.Engine filters protect the fuelinjection pumps and nozzles andshould never be removed orbypassed. The comparison in Figure7 demonstrates the very tightclearance in the fuel system and thesize of visible particles.Figure 7Sizes of ParticlesPrimary filters will extend enginefilter and transfer pump life. Waterand sediment traps can be includedupstream of the transfer pump, butpump flow must not be restricted.Filter Micron RatingsCaterpillar specifies actual filtercapability, rupture strength, thecapacity for holding dirt, flowresistance, filter area, etc.Caterpillar does not specify filter orfilter paper by micron rating. Micronratings are easily confused for thefollowing reasons:• The test for micron ratings isnot repeatable at differentlabs. One manufacturer maygive a rating of 10 microns(0.00039 in.), another at 2microns (0.000079 in.) and athird may rate a particularfilter media (paper) at 15microns (0.00059 in.).• There is no consistentrelationship between micronrating and actual filtrationefficiency. The entire filterneeds to be tested, not justthe media (paper).• The micron rating does notshow what happens to a filterover time. The test providesno information about how afilter will stand up undercontinual use.Micron ratings are overemphasized;a 10-micron filter will not alwaysstop a 10-micron particle. Manyreputable filter manufacturing firmsare drifting away from micronratings to more conclusive tests.Smaller micron ratings are notnecessarily better.If all other factors (area) wereequal, a smaller micron numbermedia (paper) has a severedrawback: it has less capacitybefore plugging and needs to bereplaced more often. The size of thepores in the paper needs to bebalanced against the costs of thefilter replacements.Common questions are:Page 24©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systems• What is the maximum particlesize which can pass throughCaterpillar filters?• What is the differencebetween nominal size andabsolute size filters?For example: A nominal 10 micronfilter media (paper) will pass someparticles up to about 50 microns insize. Theoretically, an absoluterating of 10 microns will stop allparticles larger than 10 microns. Infact, filters with absolute micronratings of 10 will pass someparticles larger than 10 microns dueto the irregularity of the paperweave. New filters may pass largerparticles than they will after only afew hours of use.As a rule, Caterpillar fuel filtermedia (paper) is about 3 micronsnominal, 20 microns absolute. Oilfilter media (paper) is about 10microns nominal, 50 micronsabsolute. These are approximatevalues only.Filters are not effectively comparedon the basis of micron rating alone.Evaluate filters on the basis of theirability to collect foreign material as awhole.Primary Fuel Filter ElementSpecificationThe primary fuel filters elementsshould have the following properties:• Mesh Size: 32 x 28 strandsper cm (70 x 80 strands perin.)• Element: Monel wire clothmaterial or equivalent• Element Area: 645 cm2 (100in.2) or greater• Opening Size: 0.1778 mm x0.2235 mm (0.007 in. X0.0088 in.)Duplex Fuel FiltersMany Caterpillar Engines can beequipped with duplex fuel filters asshown in Figure 8.Figure 8These filters may be serviced(change elements), without shuttingoff the engine. There are two types:the symmetrical type, which hastwo identical filter sets and themain-auxiliary type, which has amain filter set and a smaller capacityauxiliary filter set. A special valveconnects the two sets of filters ineach type. The valve routes the fuelto be filtered through either or bothsets of filters.Both filter sets can be usedsimultaneously to extend runningtime in an emergency.Duplex filters for fuel andlubricating oil allow extendedoperation without interruption.©2005 Caterpillar®All rights reserved. Page 25

Diesel Fuels & Diesel Fuel SystemsApplication and Installation Guide• The main and auxiliary filtersystems allow changing eitherthe main or auxiliary filterelements with the enginerunning under load.• Generally, the same elementsare used in both systems, andare capable of providingadequate filtration for at least100 hours full load runningtime with reasonably cleanfuel and oil.• Use pressure gauges todetermine when filters mustbe changed.• Avoid mounting filters nearthe radiator fan, because afuel or oil leak duringreplacement could create afire hazard. (As eithersubstance passes through thefan it can be atomized, andtherefore easier to ignite.)Plus, coated radiator fins trapdirt which can diminishcooling capability.Water SeparationWater in the diesel fuel isabsolutely unwanted as it will causedamage to the engine and itscomponents. Water appears in thefuel because of condensation,handling and environmentalconditions. Environmental conditionsrelate to the humidity of someclimates. Water in the fuel will bemore prevalent in humid climates.Water can impact the fuel systemin the following ways.• If water appears in theinjection system, the fuel willnot be able to lubricate as it issupposed to and it will lead toearly wear.• Water together with dieselfuel will form microbiologicalgrowth which will build upsludge. Sludge will causewear of the filter system andinfluence the injectionperformance.• Iron will oxidize when incontact with water and caninfiltrate the fuel. The ironoxide will cause injector wear.Engines using high injectionpressure fuel pumps must beprotected from water and sedimentin the fuel. It is extremely importantto maintain water and sedimentlevels at or below 0.1%.Note: Water and sediment collectingin fuel tanks may give theappearance that poor quality fuelwas delivered to the site.Several methods can be used toremove excess water and sedimentfrom the fuel system:• A water and sedimentseparator can be installed inthe supply line ahead of thetransfer pump. The separatormust be sized to the handlethe fuel being consumed bythe engine as well as fuelbeing returned to the tank.Page 26©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systems• Coalescing filter systems workeffectively to removesediment and water. If thelevel in the day tank is notmaintained at a consistentlevel, install them betweenthe main tank and the daytank. If proper day tank levelsare maintained, a smallersystem can be used betweenthe main tank and the daytank to clean only the fuelbeing burned. These filterscan plug and careful attentionmust be given to fuel pressurelevels at the injectors to guardagainst misfiring.• A centrifuge system can beused, particularly if the fuelquality consistently fallsbelow the defined limitsdiscussed in this guide.CentrifugesThe centrifuge represents the mostexpensive and complex method ofwater separation, but it is the mosteffective. It is used extensively inmarine, offshore and powergeneration applications where acontinuous power supply isessential, and the continuous supplyof clean fuel cannot be left tochance. A typical distillate fuelcentrifuge schematic is shown inFigure 9.A centrifuge manufacturer shouldbe consulted to determine the propercentrifuge type, size and flowrequirements for a specificapplication.While Figure 9 shows a singlecentrifuge schematic, manyapplications will require the use oftwo (2) centrifuges, with one of thecentrifuges acting as a standby.The required flow rate of acentrifuge can be approximated asfollows:P x b x 24 x 1.15Q =R x tWhere:Q= Flow required, L/hrP= Total Engine Output, kWb= Fuel Consumption, g/kW-hrR= Density of fuel, kg/m3T= Daily separating time inautomatic operation: 23 hrOr:Q =f x be x 24 x 1.15R x tWhere:Q= Flow required, gal/hrP= Total engine output, bhpBe= Specific fuel consumption,lb/bhp-hrR= Density of fuel, lb/galT= Daily separating time inautomatic operation: 23 hrNote the following considerationsfor configuring a centrifuge.• The centrifuge manufacturershould assist in the finalcentrifuge selection.• The centrifuge flow has beenincreased by 15% as a safetyfactor for operationaltolerances.©2005 Caterpillar®All rights reserved. Page 27

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideTypical Distillate Fuel CentrifugeSystemFigure 9Centrifuge seal water and controlair requirements must be specifiedby the centrifuge manufacturer.Sample PointsThe centrifuge operating efficiencyis checked by drawing samples fromboth sides of the centrifuge.Suction StrainerInstall a simplex strainer ahead ofthe centrifuge supply pump and usea stainless steel basket withperforations sized nominally at 0.8mm (0.03125 in) to protect thepump. The strainer body is normallymanufactured from cast iron orbronze.Centrifuge Supply PumpMount an electric motor drivensupply pump separately from thecentrifuge and size it appropriatelyfor the centrifuge flow. Thefollowing pump characteristics areprovided for guidance:• Operating pressure - to suitconditions of piping system• Operating fluid temperature -38°C (100°F)Page 28©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systems• Viscosity for sizing pumpmotor - 500 cStCentrifuge Fuel HeaterThe heater is sized using the pumpcapacity and the temperature riserequired between the settling tankand the final centrifuge. The heatershould be thermostatically controlledand set to maintain fuel temperatureto the centrifuge within ± 2°C (±4°F). The maximum preheatingtemperature for distillate fuel is 40°to 50°C (104° to 122°F).©2005 Caterpillar®All rights reserved. Page 29

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideMiscellaneous Fuel System ConsiderationsFuel TemperatureThe fuel temperature supplied tothe engine can affect unit injectorlife and maximum power capability.Reduced lubrication capability due tohigh temperature/low viscosity fuelmay result in component scuffing.The minimum allowable viscosity atthe injectors is 1.4 cSt. A maximumfuel temperature limit of 66°C(150°F) to the unit injectors,regardless of fuel viscosity, preventscoking or gumming of the injectors.The maximum fuel viscosity to theunit injectors of 20 cSt preventsoverpressure damage to theinjectors.Maximum fuel temperature limitsto the low-pressure fuel transferpump for Common Rail Fuel systemsvary with engine model. Values arelisted below in Table 4.Maximum Allowable Inlet FuelTemperature to the Low Pressure FuelTransfer Pump for Common RailApplicationsC17570°C (158°F)C7, C9, C15, C18 80°C (176°F)Table 4The engines are power set at thefactory, and higher fueltemperatures will reduce maximumpower capability. The fuel stoppower reduction is 1% for each 6°C(10°F) fuel supply temperatureincrease above the maximum fueltemperature limit. If the engine isoperating below the fuel stop limit,the governor will add fuel asrequired to maintain the requiredengine speed and power.Fuel CoolersAs mentioned earlier in the BasicFuel System description, Caterpillardiesel engine fuel delivery systemsare designed to deliver more fuel tothe engine than is required forcombustion, with the excess beingreturned to the fuel tanks. Thisexcess fuel, on many engines, isused for cooling and lubricating ofthe pumps and injection systemsand in doing so picks up engine heatand can raise the temperature of thefuel in the tanks.As previously specified, enginepower will be reduced if the fueltemperature exceeds the maximumlimit because of the expansion of thefuel (low viscosity). With very lowviscosity, the oil loses the capabilityto lubricate and damage to theinjection components will occur.Proper considerations regardingfuel tank location and size will helptemperature control. If the tank isproperly located and sized so theaccumulated heat will not beobjectionable when temperaturestabilizes, then nothing more needsto be done. If the stabilized fuel tanktemperature is high, the returningfuel should be cooled.The following factors affect theneed for fuel cooling equipment.Page 30©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systems• Length of periods ofcontinuous operation; If theoperating periods are short,the amount of heat returnedto the fuel tanks will berelatively small. Fuel coolersare not generally required forengines used in applicationsrequiring intermittentoperation.• Length of time betweenperiods of operation; if thetime between periods ofoperation is long, the heat willhave an opportunity todissipate.• Volume of the fuel tank; If thevolume of the fuel tank islarge (larger than 11 000 L[3,000 gal]), it will accept agreat deal of heat before thetemperature of the fuelleaving the tank increasessignificantly.Note: Day tank sizing is critical tomaintain the desired fuel supplytemperature. Fuel coolers may berequired. For a more detaileddiscussion of required fuel tankvolume, see the Day Tank Sizing(When Serving as a Heat Sink)section in Appendix 1.• Ability of the fuel tanks todissipate heat. In marineapplications for instance, fuelin contact with the shellplating, where at least 10% ofthe inside surface area of thetank is shell plating, the heatwill be easily dissipated andthe stored fuel temperaturewill remain within a fewdegrees of the ambient watertemperature.If a shell and tube type fuel cooleris required, the following materialsare suggested for the componentslisted in Table 5.ComponentShellHeadsTubesTube SheetsBafflesSuggestedMaterialRed BrassCast IronCopper NickelBrassBrassTable 5A plate type heat exchanger mayalso be used with titanium plates forseawater cooling or stainless steelplates for fresh water cooling.Refer to Sea Water Systems in theCooling Systems Application andInstallation Guide for properinstallation and maintenanceprocedures of fuel cooler in seawater applications.Fuel HeatersJust as the ability to removeexcess heat from fuel is animportant design consideration insome applications, so is the ability toadd heat to fuel in applicationsinvolving cold environments. Dieselfuel must not be too warm or toocool. Both cases will reduce life.With mid-distillate No. 1 or No. 2diesel fuel, cold weather can causewax crystals to form in the fuelsystems, partially or completelyblocking fuel flow. The addition of asmall amount of heat to the fuel©2005 Caterpillar®All rights reserved. Page 31

Diesel Fuels & Diesel Fuel SystemsApplication and Installation Guidebefore it flows through the filter(s)can prevent wax problems. The fuelwill flow through pumps and linesbut not through filters attemperature below the cloud point(where a cloud or haze appears inthe fuel).At temperatures below the pourpoint (the lowest temperature thatfuel will flow or pour), fuel will notflow in lines or pumps. The use offuel with a pour point above theminimum expected ambienttemperature is not recommended.Fuel heaters will often solve cloudpoint problems but not pour pointproblems unless applied to the entirefuel storage volume.Consider the following suggestionswhen applying fuel heaters toCaterpillar engines.• Fuel heaters should be usedwhen the ambienttemperature is below the fuelcloud point. Many types ofheaters can be used;however, the fuel should beheated before the first filter inthe fuel system. Fuel heatersshould not be used when theambient temperature exceeds15°C (60°F). Under nocondition should the maximumfuel temperature at the outletof the fuel heater exceed thelimit specified on the previouspage.Page 32• Heaters used should becapable of handling themaximum fuel flow of theengine. The restriction createdshould not exceed publishedlevels of the engine (publishedvalues for fuel flow andallowable restriction can befound in the TMI).• Coolant may be taken fromtaps on the engine whenusing the engine as a heatsource. Care must be taken toassure that coolant shuntingto one system does notadversely affect anothersystem, and that both haveadequate flow.CAUTION: Failed water sourced fuelheaters can introduce excessivewater into the engine fuel systemand cause injector failure.Maintenance responsibility of thistype of heater must be clearlydefined.• Fuel heaters offered byCaterpillar use engine coolantto heat the fuel and preventthe development of solid waxparticles.• When any fuel heater is usedand ambient temperatures arebelow approximately 0°C(32°F), the engine should bestarted and run at low idleuntil the engine temperaturerises slightly. This allows heattransfer to the fuel beforehigh fuel flow rates at highpower output are experiencedby the system. This willreduce the possibility of waxplugging the fuel filter shortlyafter a cold start.©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsPartial Load OperationExtended operation at low idle orat reduced load may cause increasedoil consumption and carbon buildupin the cylinders. Carbon buildupresults in a loss of power and/orpoor performance. When possible,apply a full load at least on an hourlybasis. This will burn excess carbonfrom the cylinders.Burning Used Crankcase OilWith legislation and ecologicalpressures, it is becomingincreasingly difficult to dispose ofused oil. The burning of usedcrankcase oil in 3600 engines is notrecommended due to the detrimentaleffects on exhaust emissions.However, if ancillary methods ofreducing exhaust emissions toacceptable limits are used, or ifemissions are not a problem, burningcrankcase oil in 3600 engines ispossible with the followingguidelines.• It is necessary to collect,store, and dispose of usedcrankcase oil from enginescorrectly. It is not acceptableto dump used crankcase oilinto the oceans, rivers, andharbors from vessels oroffshore drilling andproduction platforminstallations. It may benecessary for engineoperators to consider burningcrankcase oil in theirCaterpillar engines. This canbe done, providing theprecautions below arecarefully followed:• Only diesel engine crankcaseoils can be mixed with thediesel engine fuel supply. Theratio of used oil to fuel mustnot exceed 5%. Prematurefilter plugging will occur athigher ratios. Under nocircumstances should gasolineengine crankcase oil,transmission oils, specialhydraulic oils not covered byCaterpillar recommendations,grease, cleaning solvents,etc., be mixed with the dieselfuel. Do not use crankcaseoils containing water orantifreeze from engine coolantleaks or poor storagepractices.• Adequate mixing is essential.Lube oil and fuel oil, oncemixed, will combine and notseparate. Mix used filteredcrankcase oil with an equalamount of fuel, then add the50-50 blend to the supplytank before new fuel is added(maintaining the 5% used oilto-fuelratio). This procedureshould normally providesufficient mixing. Failure toachieve adequate mixing willresult in premature filterplugging by slugs of undilutedoil.©2005 Caterpillar®All rights reserved. Page 33

Diesel Fuels & Diesel Fuel SystemsApplication and Installation Guide• Filter or centrifuge used oilbefore putting it in the fueltanks to prevent prematurefuel filter plugging,accelerated wear, or pluggingof fuel system parts. Soot,dirt, metal, and residueparticles larger than 5 microns(0.000197 in.) should beremoved by this process. Iffiltering or centrifuging is notused before adding the oil tothe fuel, primary filters with 5microns (0.000197 in.)capability must be locatedbetween the fuel supply andengine. These will requirefrequent servicing.• Clean handling techniques ofthe used crankcase oils areessential to preventintroducing contaminants fromoutside sources into the dieselfuel supply. Care must betaken in collecting, storingand transporting the usedcrankcase oil to the diesel fueltanks. Diesel fuel day tanksight glasses may becomeblackened in time due to thecarbon content in thecrankcase oil. Ash content ofthe lube oil added to the fuelmay also cause accumulationof turbocharger and valvedeposits more rapidly thannormal.Continuous BlendingIf the installation warrants, usedlubricating oil can be blended andused in the engine in a continuousmanner. The normal method uses acentrifuge module similar to Figure9. The following informationdescribes this system.Centrifuge No. 1Engine crankcase oil iscontinuously centrifuged exceptwhen the clean waste oil tank islow, at which time the dirty wasteoil is centrifuged and directed to theclean waste oil tank.Centrifuge No. 2Distillate fuel/oil mixture daytank iscontinually centrifuged.Metering PumpAdds up to 5% clean waste oil tothe distillate fuel (from the mainsupply tank) when the daytank lowlevel switch calls for more fuel.Static MixerRuns when the metering pump ison to insure a proper homogeneousmixture of the fuel and clean wasteoil.The centrifuge module iselectronically controlled and includesthe components within the dottedline as shown in Figure 10. Size thesystem for appropriate fuel delivery.Page 34©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsFigure 10©2005 Caterpillar®All rights reserved. Page 35

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideFuel Conservation PracticesFuel costs typically represent thesingle highest operating costassociated with any diesel engineapplication. This has promotedvarious fuel conservation practicesthat can usually be applied to allapplications.• Avoid fuel spillage. Do notoverfill the fuel tank. Fuelexpands when warm and mayoverflow, especially whentank is not designed correctly.• Operate the engine with agood electrical system. Onebad cell in a battery willoverwork the alternator,consuming more enginehorsepower and fuel. A poorelectrical system can also leadto hard starting, whichencourages excessive idling.• Size the engine or generatorset to the job. Engines operatemore efficiently at relativelyhigh load factors.• Do not increase fuel settingsto obtain more power.• Make sure all air hoses andconnections do not leak.Leaks keep the compressorworking unnecessarily.• Make sure the turbocharger isturning freely so that properair-fuel ratio is maintained. Aclean burning exhaust shouldindicate these items arefunctioning correctly.• Operate the engine with athermostat all year; coldengines consume more fueland wear out more quickly.• Keep air cleaners clean. Usean air cleaner restrictionindicator to avoid guessing atair cleaner condition.Page 36©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsAppendix 1Day Tank Sizing (WhenDay Tank Serves as a HeatSink)The fuel supply temperature mustbe within specified limits foroptimum injector life and maximumpower capability.Fuel systems without fuel coolersrely on the day tank to dissipate theheat of fuel returning from theengine. Day tank temperatures areaffected by the following conditions.• Day tank wetted surface area(including tank bottom)• Engine(s) fuel consumptionrate• Day tank replenishing level• Storage tank fuel temperature• Ambient temperature• Spaces contiguous to the daytank (void tanks, cofferdams,vessel shell plating, etc.)• Return fuel temperatureTank temperature calculation areperformed in five [5] steps. The firstdetermines the fuel mass in the tankat each time interval. The secondstep is based on a fuel mixtemperature resulting from theengine driven transfer pump flowrate to the engine and the returnflow rate to the day tank. The thirdstep determines the day tank fuelheight for each incremental timeelement. Typically, the calculationswill be based upon a 30-60 minuteiterative time function. The endpoint for the calculation is assumedto be when the day tank is refilled.The fourth step approximates theheat transfer from the tank to thesurrounding environment due to thetemperature difference between thefuel mix temperature and theambient temperature. Thisconvective heat transfer thendetermines the resultant tanktemperature. The fifth step evaluatesthe impact of the final fuel supplytemperature on the engine’smaximum power capability.The included example calculationsshould only be used to providegeneral guidance. If the day tanksize is marginal, use a fuel cooler.To simplify the followingcalculations, it is assumed the daytank walls are surrounded by freemoving air. If the tank walls arecontiguous to the shell plating, heattransfer from the day tank will beenhanced. Conversely, if the daytank is bounded by void spaces andcofferdams, heat rejection from theday tank will be retarded. Typically,most day tanks are located withvarious combinations of thepreceding boundary elements. Theindividual performing the evaluationmust be familiar with the installationas well as the fundamentalengineering concepts of the formulasused in the calculations.Day Tank CalculationsThe following information isrequired to perform the calculations:• Engine model• Engine developed power (MCRor CSR)• Engine speed©2005 Caterpillar®All rights reserved. Page 37

Diesel Fuels & Diesel Fuel SystemsApplication and Installation Guide• Brake specific fuelconsumption (bsfc)• Initial day tank fueltemperature• Storage tank fuel temperature(Make-up)• Ambient air temperature• Day tank length, width, andheight• Typical full day tank fuelheight (assume 95% of tankcapacity)• Engine fuel transfer pumpflow rate (see page 6 of thissection)• Fuel heat rejection from theengine (see page 6 of thissection)• Incremental time elementDay Tank Thermal CapacityCalculationExample:• Application: Single mainengine• Engine Model: 3612• Rated Power: 4640 bhp (CSR)• Rated Speed: 900 rpm• bsfc: 0.326 lb/bhp-hr• Initial Day Tank FuelTemperature = 85°F• Storage Tank Temperature =85°F• Ambient Air Temperature =95°F• Day Tank Dimensions:o Length (L) = 12 ft.o Width (W) = 8 ft.o Height (H) = 8.42 ft.• Fuel Height (@ 95% of totalCapacity) (H) = 8 ft.• Engine Fuel Oil Transfer PumpFlow Rate: qxfer = 19.0 gpm• Heat rejection from engine tofuel oil: Q = 1252 Btu/min• Incremental time element: t =60 min.Assume that the day tank will bereplenished from the fuel storagetanks when the day tank level fallsto approximately 50-55% of normaloperating capacity.Some of the data above must beconverted to other units prior tobeginning calculations. The followingformulas can be used:1. Engine Driven Transfer PumpMass Flow Rate = Mxfer (lb/min)Assume: #2 DO with an APIgravity of 35 (7.1 lb/gal)Mxfer = qxfer x 7.1 lb/gal = 19.0gpm x 7.1 lb/gal = 134.9 lb/min2. Engine burn rate under full loadconditions:a. Burn rate (gpm)==bsfc x bhp x 1 Hr.Fuel density x 60 min.0.326 lb/bhp-hr x 4640 bhp x 1 hr.7.1 lb/gal. x 60 min.= 3.55 gpmb. Fuel mass flow burn rate= MBR (lb/min)= 3.55 gpm x 7.1 lb/gal= 25.21 lb/min3. Engine fuel return rate under fullload conditions:Page 38©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systemsa. Fuel return flow rate= qrtn (gal/min)= Supply rate - burn rate= 19.0 gpm - 3.55 gpm= 15.45 gpmb. Fuel return mass flow rate= Mrtn (lb/min)= 15.45 gpm x 7.1 lb/gal= 109.70 lb/min4. ∆TENG of fuel = (Tsupply - Trtn)∆TENG === 22.83°FQMrtn x Cp1252 Btu/min(109.70 lb/min x0.5 Btu/lb-°F)5. 95% Capacity of Diesel Oil DayTank, (lb)Weight density (p) for #2 dieseloil = 52.42 lb/ft 3MDT = L x W x H x pDO = 12 ft x8 ft x 8 ft x 52.42 lb/ft 3 =40258.6 lb.Step 1Calculate the fuel mass in the daytank at specific time intervals:Day Tank Fuel Quantity = MDT -(MBR x t)Where:MDT = Day tank contents at aspecific time step (lbs)MBR = Engine fuel consumption(lb/min)t = Incremental time step (min)Assume the day tank is replenishedat 55% of initial quantity of fuel.Prepare a table of volumes as shownbelow for this example. Refer toTable 6.IncrementalTime (Min)Tank FuelQuantity (lb)Capacity(%)0 40258.6 100.060 38746.0 96.2120 37233.4 92.5180 35720.8 88.7240 34208.2 85.0300 32695.6 81.2360 31183.0 77.5420 29670.4 73.7480 28157.8 69.9540 26645.2 66.2600 25132.6 62.4660 23620.0 58.7720 22107.4 54.9Refill 40258.6 100.0Table 6©2005 Caterpillar®All rights reserved. Page 39

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideStep 2Calculate the fuel oil mix temperature (Tmix):MDT(t -1) - [(Mxfer x t)] TDT(t -1) + (MRTN x t) x (TDT(t -1)+ ∆ TENG)MDT(t -1) - (MBR x t)Where:MDT = Day tank contents at aspecific time step (lb)Mxfer = Engine transfer pumpmass flow rate (lb/min)T = Incremental time step(min)TDT(t -1) =Day tank temperature forprevious time step orstarting temperature (°F)MRTN =Engine return mass flowrate (lb/min)∆T ENG= Fuel temperature riseacross the engine (°F)MBR = Engine fuel consumption(lb/min)Values for the example calculation:MDT(t -1) = Day tank contents fromprevious time step (lb)Mxfer = 134.9 lb/minT = 60 min.TDT(t -1) =Initial day tanktemperature is used forfirst iteration, 85°FMRTN = 109.70 lb/min∆TENGMBR= 22.83°F= 25.21 lb/minTmix =[(40258.6 - (134.9)(60))(85)] + [(109.70)(60)(85 + 22.83)][40258.6 -(25.21)(60)]Tmix = 88.9°F @ t = 60 min.Page 40©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsThis calculation is repeated foreach increment (t).Prepare a summary table as shownin Table 7 for each increment (t).IncrementalTime (Min)MixTemperature (°F)0 85.060 88.9120 92.9180 97.1240 101.5300 106.1360 110.9420 116.0480 121.3540 126.9600 132.9660 139.3720 146.1RefillTable 7©2005 Caterpillar®All rights reserved. Page 41

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideStep 3Calculate the height of fuelcontained in the day tank at t =incremental time step. Prepare asummary table for each timeincrement (t) as shown in Table 8.H=MDTp x L x WWhere:H = Height of fuel in the tankMDT = Fuel contained in the daytank at each incremental timestepp = Weight density of #2 DO(52.42 lb/ft3)L = Length of day tank (12 ft)W = Width of day tank (8 ft)Incremental Time(min)Table 8Height (ft)0 8.060 7.7120 7.4180 7.1240 6.8300 6.5360 6.2420 5.9480 5.6540 5.3600 5.0660 4.7720 4.4Refill 8.0Page 42©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsStep 4Calculate the heat transferred between the fuel in the day tank and theatmosphere, the ∆T of the fuel in the day tank due to the heat transfer, andthe resulting fuel day tank temperature.a. Heat transferred between the day tank and the atmosphere:(TMIX + TDT)QTK = U x [ (H x (2L + 2W) + (L x W) ] x[ TAMB - 2 ] x tWhere:QTK =Heat transfer to/fromatmosphere (Btu)This considers 6mm (0.25in.) steel plate forming thetank boundaries, and thefilm coefficient for air andoil. The air side filmcoefficient is predominantwhen compared to the oilside film. The tank thicknesshas a negligible effect.U = Coefficient of heattransfer, (0.0424 Btu/min•ft 2 •°F)L = Day tank length (ft)W = Day tank width (ft)TAMB = Ambient temperature (°F)TMIX = Mix temperature of returnfuel and fuel in tank (°F)TDT = Day tank temperatureresulting from heat transferto/from day tank (°F)T = Incremental time step(min)H = Fuel height for specifictime step (ft)b. Temperature change in the daytank resulting from heat to/fromday tank:Where:∆TDTQTKMDTCP∆ TDT =QTKMDT x Cp= Temperature change offuel in the day tank (°F)= Heat transfer to/fromatmosphere (Btu)= Mass of fuel in day tank(lb)= Specific heat of #2 MDO= 0.5 Btu/lb •°Fc. Day tank temperature resultingfrom heat transfer to/from daytank:TDT = TMIX + ∆TDTWhere:TDT = Day tank temperature(°F)TMIX = Mix temperature of returnfuel and tank fuel (°F)∆TDT = Temperature change ofday tank (°F)These three calculations areinterdependent in nature. First, QTK isdetermined for the first incremental©2005 Caterpillar®All rights reserved. Page 43

Diesel Fuels & Diesel Fuel SystemsApplication and Installation Guidetime step. The resulting value for QTKis then used to compute the ∆ TDT.∆TDT is then used to determine TTK.This process is then repeated foreach incremental time step.Example a.:(TMIX + TDT)QTK = U x [ (H x (2L + 2W) + (L x W) ] x[ TAMB - 2 ] x t(88.9 + 85)QTK =0.0424 x [7.7 (40) + 96] x[ 95 - 2 ] x 60QTK = 8283.6 BtuExample b.:∆ TDT =∆ TDT =∆ TDT =QTKMDT x Cp8283.6 Btu(38746.0 lb) (0.5 Btu/lb °F)0.43 °F (From atmosphere to day tank)Example c.:TDT = TMIX + ∆TDTTDT = 88.9 °F + 0.43°FTDT = 89.3 °FThis series of calculations is then repeated for the subsequent incrementaltime steps.Page 44©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsPrepare a summary table for each time increment (t) as shown in Table 9.Incremental Time Heat Rejection to/from Temperature Chg. in Day Tank Temperature(min)Day Tank (Btu) Day Tank (°F)(°F)0 - - 85.060 8283.6 0.43 89.3120 4069.7 0.22 93.2180 -4.0 0.00 97.1240 -4022.0 -0.24 101.3300 -7966.3 -0.49 105.6360 -11818.7 -0.76 110.2420 -15561.4 -1.05 114.9480 -19257.8 -1.37 120.0540 -22802.6 -1.71 125.2600 -26253.3 -2.09 130.8660 -29655.5 -2.51 136.8720 -32973.6 -2.98 143.1Refill - - 116.9Table 9The last part in Step 4 determines the day tanktemperature after refilling (TDT refill):[ (MDT full - MDT tn ) x TMUF] + (MDT tn x TTK n )TDT refill =MDT fullWhere:MDT fullMDT tnTMUFTTK nExample:TDT refill == Capacity of day tank, (lb)= Fuel in day tank prior to refilling, (lb)= Temperature of make-up fuel, (°F)= Temperature of tank fuel prior to refilling, (°F)[(40258.6 - 22107.4) x 85] + (22107.4 x 143.1)40258.6 lbTDT refill = 116.9°F©2005 Caterpillar®All rights reserved. Page 45

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideStep 5The last step calculates themaximum power capability of theengine at the resultant day tanktemperature for each time interval. Asummary table for each increment (t)is also prepared and shown in Table10:Note: The engines are power set atthe factory with 30 ±3°C (86±5°F) fuel to the engine transferpump. Higher fuel temperaturesreduce maximum power capability.The fuel stop power reduction is 1%for each 5.6°C (10° F) fuel supplytemperature increase above 30°C. Ifthe engine is operating below thefuel stop limit, the governor will addfuel as required to maintain therequired engine speed and power.(TDT - Tref ) 1Pcorr = Prated x[ 1 - X10°F 100 ]Where:Pcorr = Corrected Engine Power,bhpPrated = Rated bhpTref = 86° (Power setting)TDT = Actual day tank fueltemperature, °FExample:For t = 60, the corrected power ofthe engine is:(89.3°F - 86°F) 1Pcorr = 4640 bhp x [ 1 - X10°F100 ]Pcorr = 4625 bhpIncrementalTime (min)Day TankTemp. (°F)CorrectedEngine Power(bhp)0 85.0 -60 89.3 4625120 93.2 4607180 97.1 4588240 101.3 4569300 105.6 4549360 110.2 4528420 114.9 4506480 120.0 4482540 125.2 4458600 130.8 4432660 136.8 4405720 143.1 4375Refill 116.9 4497Table 10ConclusionThe previous calculations indicateday tank fuel temperatures can havean effect on the maximum powercapability of the engine. Theexample was based upon a fixedpitch propeller application. Typically,a fixed pitch propeller is selectedand sized to absorb 85-90% of theengine's name plate rating. In thisexample, this would equate to 3950-4175 bhp. The lowest calculatedcorrected power was determined tobe 4375 bhp. This would leave a 5-10% power margin and vesselperformance would not be affected.While vessel performance may notbe affected in this example, themaximum fuel temperature of143.1°F will put the fuel viscositynear or below the minimumallowable viscosity of 1.4 cSt at thePage 46©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systemsinjectors depending on the type ofdistillate fuel being used. In addition,the temperature of the fuel in thetank after refill is now 116.9°Finstead of 85°F as used at thebeginning of the iteration. Therefore,continued operation at full load onthis fuel tank would cause the fueltemperature to rise even higher thanthe maximum temperature shown inthis iteration. To protect the fuelinjectors a fuel cooler should beused in this application, despite thefact that available engine power isstill acceptable.Aside from the impact on engineperformance, maximum fuel tanktemperatures are also established byvarious marine classificationsocieties and regulatory bodies.Their interest is based upon theincreased risks of fire that resultsfrom elevated fuel temperatures.Useful Fuel Formulas and DataThe following information can be useful in sizing fuel coolers and heaters:Specific Gravity (SG) and DensityAPI Gravity = (141.5/SG) - 131.5SG = 141.5/(API Gravity + 131.5)SG =Density998 kg/m 3Density (kg/m 3 ) = SG x 998 kg/m 3 1 lbm/ft 3 1 ft 3Density (lbm/gal)= SG x 998 kg/m 3 x16.02 kg/m 3 x7.48 galMass Flow RateM (kg/sec) = Density (kg/m 3 ) x1m 31000 LxFlow Rate (L/min)60 (sec/min)M (lbm/min) = Density (lbm/gal) x Flow Rate (gal/min)©2005 Caterpillar®All rights reserved. Page 47

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideSpecific Heat (cp)Table 11 shows typical specific heat values for two different API gravityfuels in Btu/lbm-°F:API GravityTable 1138°C(100°F)60°C(140°F)82°C(180°F)93°C(200°F)115°C(240°F)30 0.463 0.482 0.501 0.511 0.53040 0.477 0.497 0.516 0.526 0.5460.5461 Btu/lbm-°F = 4.186 kJ/kg-°CHeat RejectionQ (kW) = M (kg/sec) x cp (kJ/kg-°C) x ∆T (°C)Q (Btu/min) = M (lbm/min) x cp (Btu/lbm-°F) x ∆T (°F)Page 48©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel SystemsAppendix 2Crude Oil FuelNote: Crude oils are not suitable foruse as fuel in all engine applications.The suitability of these fuels for useis determined on a case-by-casebasis. A complete fuel analysis isrequired.NOTICE: Use of permissible crude oilfuels can result in highermaintenance costs and in reducedengine service life.NOTICE: Caterpillar does notrecommend using any of the heavierfractions such as residuals orbottoms in engines that areconfigured to use distillate dieselfuel. Failure to follow thisrecommendation will result in severewear of components and enginefailure.Residual fuels or blended fuelswith residuals are unsuitablebecause they have a high viscosityrange, low ignition quality and highvanadium and sodium contents thatshorten engine life. Such fuels maycause high wear rates in the fuelsystem, on the piston rings, cylinderliners, and exhaust valves. Also,filter problems and deposits in thepiston ring belt may be evidenced.Special crude oil fuel pretreatmentequipment may be required and isavailable from suppliers of fueltreatment equipment. Also, it maybe essential to start and stop theengine on a better quality, ASTMNo. 2-D type fuel to preventplugging and sticking fuel systemcomponents and to permitsatisfactory starting capability.The same diesel power ratings maynot always apply for Caterpillarengines burning crude oil.Reasonable engine service life canbe achieved when proper proceduresare followed. However, the greaterrisks involved make it good practiceto include slightly higher than normalmaintenance costs when figuring theoverall economics to be gained.A fuel analysis should beperformed. Include a distillationcurve. Operation at light load is notrecommended. On occasion,operation at 50% load hasreportedly caused smoking.Engines for crude oil fuel operationshould be equipped with highertemperature thermostats, bypasscentrifugal oil filter, and fuel injectorpushrod keepers.Pretreatment of Crude Oils1. The crude may contain excessiveamounts of sediment and waterthat will require removal beforethey get to the engine. This canusually be accomplished with asettling tank, Figure 11, acentrifuge or special filteringequipment or a combination ofthese methods. The crude mayalso contain solid particles ofwax at ambient temperature thatwould plug the filters rapidly. It isimpractical to try to remove thewax, but the crude can be heatedsufficiently to dissolve it. Theamount of heat needed will varyfrom one crude to another and©2005 Caterpillar®All rights reserved. Page 49

Diesel Fuels & Diesel Fuel SystemsApplication and Installation Guideeach situation requires anassessment. Jacket-water heatedfuel filters, available from fuelequipment suppliers, are oftensuitable for heating the crude. Ifthis is not appropriate for youapplication, an external heatingsystem will be necessary.2. The crude oil must not have toohigh a viscosity. For maximumlife and minimum maintenance ofthe fuel pumping and injectionsystems, the viscosity of thecrude oil in these systems shouldbe within 1.4 to 20 cSt at 104°F(40°C). If the crude’s naturalviscosity is higher than this, itmay be heated or diluted toreduce it. The degree of heatingrequired will vary from one crudeoil to another and will have to beestablished in each case. Anothermethod of reducing viscosity isto blend the original crude with asufficient amount of lighterdistillate material. Again, theblending proportions would haveto be determined for each crudeoil.3. The crude must have a cetanenumber of at least 40. Thisbrings its distillationcharacteristics into the picture.The cetane number should bedetermined by actual engine testbecause calculated numbers ofcrude oils are unreliable. Thecetane number of a crude oil is afunction of its composition.Crude is generally subdivided intofractions by boiling temperatures.The combination of the gasolineand naphtha fractions, whichhave low cetane numbers, shouldnot exceed 30% of the totalcrude. The kerosene, distillateand gas oil fractions combinedshould make up at least 30% ofthe total because they have highcetane numbers.4. Another problem created byhighly volatile crude oils (lowinitial boiling points) is vaporlocking of the fuel system. Thissituation can be handled by an“air eliminator.” This, in somecases, can be an ordinary floattypesteam trap inverted, but itshould be made of corrosionresistantmaterials. It should belocated after the auxiliary filters.If the engine is stoppedoccasionally and allowed to cool,coagulation may build up in thisvapor trap and cause it to beinoperative.5. The proper oil changerecommendation must be made ineach case. Many crude oilscontain large amounts of materialthat accelerate lube oildeterioration. For this reason, thestandard change period withrecommended oils should bereduced by one-half. From thispoint, the length of change periodwith crude is determined bysulfur content the same as withdistillate fuels. With 0.4-1.0%sulfur, the change period shouldagain be reduced by one-half.When sulfur content exceeds1.0%, still further reduction isrecommended. In many cases, itmay be desirable to install alarger capacity lube oil system toPage 50©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systemsavoid short oil changes. The useof Caterpillar S•O•S SM , is stronglyrecommended.Crude Oil MaintenanceIntervalsEngine inspection intervals shouldbe reduced by 50% when usingcrude oil as fuel, and maintenanceroutines should be modified basedon the results of these increasedinspections.Crude Oil Settling TanksA great deal of sludge can beremoved from crude oil by propersettling. A recommended settlingsystem consists of two conebottomedtanks, Figure 11, eachholding a little more than four daysusable supply of fuel.Sludge in the bottom third isdiscarded before refilling. The tanksmust be housed in a heated building,and each fitted with heating coils.Immediately after filling, hot wateris circulated through the heating coiluntil the tank is heated to 100°F(38°C). The heat is then shut offand the fuel allowed to settleundisturbed for four days.During this time, fuel is being usedfrom a second tank. Temperatureinside the settling tank buildingshould be maintained above 70°F(21°C), and the tanks must bevented outside the building.A two-day supply of diesel fuelshould be maintained for emergencyuse. This supply can also be used tostart and stop engine when thecrude oil fuel is highly viscous orheavy with paraffins.Figure 11©2005 Caterpillar®All rights reserved. Page 51

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideCrude Oil SpecificationSpecification and ASTM Test MethodRequirementsCetane number (1) (ASTM D613)(DI Engines)Minimum 40Water and sediment % volume (ASTM Maximum 0.5%D1796)Pour point (ASTM D97) Minimum 10°F (6°C) below ambient temperatureCloud point (ASTM D97)Sulfur (ASTM D3605 or D1552)Kinematic Viscosity (2)API gravity (ASTM D287)Specific gravity (via Standards tables) (3)Gasoline and naphtha fraction(fractions boiled off below 392°F (200°C))Kerosene and distillate fraction (fractionsboiled offBCarbon residue 392°F (on (200°C) 10% bottoms) d ki (ASTM i )D524)Distillation - 10%- 90%- cracking- residue (ASTM D86)MaximumMaximumMinimumMaximumMaximumMinimumMaximumMinimumNot higher than lowest expected ambienttemperature3% - See pages 131 & 132 to adjust oilTBN for sulfur content that is above 1%1.4 cSt20 cSt (as delivered to rotary fuel injectionpumps)20 cSt (as delivered to other fuel injectionpumps)45300.80170.8762Maximum 30%Minimum 30%Maximum 3.5%MaximumMaximumMinimumMaximum540°F (282°C)716°F (380°C)60%10%Reid vapor pressure (ASTM D323) Maximum 20 psi (138 kPa)Salt (ASTM D3230) Maximum 100 lb per 1,000 barrels (220 kg per 200Gums and Resins (4) (ASTM D381) MaximumkL)5.8 grains per gallon (10 mg per 100 mL)Copper strip corrosion (ASTM D130) Maximum No. 3Flashpoint °F °C (ASTM D93) Minimum legal limitAsh % weight (ASTM D482) Maximum 0.1%Aromatics % (ASTM D1319) Maximum 35%Vanadium PPM (ASTM D3605) Maximum 4 PPMSodium PPM (ASTM D3605) Maximum 10 PPMNickel PPM (ASTM D3605) Maximum 1 PPMAluminum PPM (ASTM D3605) Maximum 1 PPMSilicon PPM (ASTM D3605) Maximum 1 PPMPPM = Parts Per Million(1) The cetane number should be determined by actual engine test because calculated numbers of crude oils areunreliable. A higher cetane number fuel may be required for operation at high altitude or in cold weather.(2) The values of the fuel viscosity are the values as the fuel is delivered to the fuel injection pumps. For ease ofcomparison, fuels should also meet the minimum and maximum viscosity requirements at 40°C (104°F) that arestated by the use of either the “ASTM D445” test method of the “ISO 3104” test method. If a fuel with a lowPage 52©2005 Caterpillar®All rights reserved.

Application and Installation GuideDiesel Fuels & Diesel Fuel Systemsviscosity is used, cooling of the fuel may be required to maintain 1.4 cSt or greater viscosity at the fuel injectionpump. Fuels with a high viscosity might require fuel heaters in order to bring down the viscosity to either 4.5 cSt orless for rotary fuel injection pumps or 20 cSt viscosity or less for other fuel injection pumps.(3) Via Standards tables, the equivalent specific gravity using the “ASTM D287” test method temperature of15.56°C (60°F) for the minimum API gravity of 30 is 0.8762, and for the maximum API gravity of 45 is 0.8017.The equivalent kg/m3 (kilograms per cubic meter) using the “ASTM D287” test method temperature of 15.56°C(60°F) for the minimum API gravity of 30 is 875.7 kg.m3, and for the maximum API gravity of 45 is 801.3 kg/m3.(4) Follow the test conditions and procedures for gasoline (motor).NOTICE: These recommendations are subject to change without notice.Contact your local Caterpillar dealer for the most up-to-date fluidsrecommendations.©2005 Caterpillar®All rights reserved. Page 53

Diesel Fuels & Diesel Fuel SystemsApplication and Installation GuideReference MaterialThe following information isprovided as an additional referenceto subjects discussed in this manual.SEBD0717Diesel Fuels and Your EngineSEBU6251Caterpillar Commercial DieselEngine Fluids RecommendationsSEBU70033600 Diesel Engine FluidsRecommendations for Lubricants,Fuels, and CoolantsREHS0104Guidelines for 3600 Heavy Fuel Oil(HFO) EnginesSENR9620Improving Component Durability:Fuel SystemsWECAPWeb Engineering Cataloging andProcuring websitePage 54©2005 Caterpillar®All rights reserved.

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