Diesel Fuels and Diesel Fuel Systems

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3600 • C175 • 3500

C32 • 3412E • 3400 • 3126B

C18 • C-16 • C-15 • C15C13 • C-12 • C11 • C-10

C9 • C-9 • C7

DIESEL FUELS & DIESEL FUEL SYSTEMS

A P P L I C A T I O N A N D I N S T A L L A T I O N G U I D E



Contents

Diesel Fuels......................................................................... 1 Common Diesel Fuel .........................................................2

Diesel Fuel Grades........................................................ 2 Low Grade...............................................................2 High Grade .............................................................. 2 American Society for Testing and Materials (ASTM)...... 2

Diesel Fuel Types .........................................................3 Crude Oil ................................................................. 3 Residual Oil or Blended Heavy Fuel Oil (HFO)................ 3 Distillate Fuel ........................................................... 3 Marine Diesel Oil ...................................................... 3 Aircraft Jet Fuels and Kerosene Type Fuels.................. 4 Biodiesel.................................................................. 4 Ultra Low Sulfur Diesel (ULSD) ................................... 4

Diesel Fuel Characteristics ............................................. 5 Diesel Fuel Selection......................................................... 6

Diesel Fuel Systems ............................................................. 7 Basic Fuel System ............................................................ 8

MUI Fuel System ...................................................... 8 MEUI Fuel System .................................................... 8 HEUI Fuel System..................................................... 9 Common Rail Fuel System ......................................... 9 ACERT Technology................................................. 10



Diesel Fuel System Design Considerations ......................... 12 Fuel Storage Systems ................................................. 12

Main Fuel Tank....................................................... 12 Auxiliary Fuel Tanks................................................ 13 Fuel Head Limiting Tank .......................................... 16 Base Mounted Tanks............................................... 16

Fuel Tank Design Considerations .................................. 17 Fuel Tank Sizing ..................................................... 17 Fuel Tank Material .................................................. 17 Fuel Tank Installation .............................................. 17 Fuel Tank Drains..................................................... 17 Fuel Tank Grounding ............................................... 18 Fuel Tank Maintenance............................................ 18

Fuel Transfer Systems................................................. 18 Fuel Transfer Pumps ............................................... 20

Fuel Piping Design Considerations................................. 21 Fuel Supply Piping .................................................. 21 Fuel Return Piping................................................... 22 Purging ................................................................. 22 Siphoning & Check Valves ....................................... 22 Material................................................................. 22 Sizing.................................................................... 23 Routing ................................................................. 23

Fuel Filtration Systems................................................ 23 Filter Micron Ratings ............................................... 24



Primary Fuel Filter Element Specification.................... 25 Duplex Fuel Filters .................................................. 25 Water Separation.................................................... 26

Miscellaneous Fuel System Considerations......................... 30 Fuel Temperature ....................................................... 30 Fuel Coolers............................................................... 30 Fuel Heaters .............................................................. 31 Partial Load Operation................................................. 33 Burning Used Crankcase Oil ......................................... 33

Continuous Blending ............................................... 34 Fuel Conservation Practices ............................................. 36

Appendix 1 ....................................................................... 37 Day Tank Sizing (When Day Tank Serves as a Heat Sink) .... 37

Day Tank Calculations................................................. 37 Day Tank Thermal Capacity Calculation ..................... 38 Useful Fuel Formulas and Data ................................. 47

Appendix 2 ....................................................................... 49 Crude Oil Fuel ................................................................ 49

Pretreatment of Crude Oils........................................... 49 Crude Oil Maintenance Intervals ................................... 51 Crude Oil Settling Tanks.............................................. 51

Reference Material ............................................................. 54



©2005 Caterpillar®All rights reserved.

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.

ForewordThis section of the Application and Installation Guide generally describes

Diesel Fuels and Diesel Fuel Systems for Caterpillar® engines listed on thecover of this section. Additional engine systems, components and dynamics

are addressed in other sections of this Application and Installation Guide.Engine-specific information and data are available from a variety of

sources. 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.



Application and Installation Guide Diesel Fuels & Diesel Fuel Systems

©2005 Caterpillar®All rights reserved. Page 1

Diesel FuelsDiesel fuel quality is an important factor in satisfactory engine life and

performance. 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 CONTENTS

Common Diesel Fuel............. 2

• Diesel Fuel Grades• Diesel Fuel Types• Diesel Fuel Characteristics

Diesel Fuel Selection .............6



Diesel Fuels & Diesel Fuel Systems Application and Installation Guide

©2005 Caterpillar®Page 2 All rights reserved.

Common Diesel Fuel

Diesel Fuel GradesA variety of fuel oils, also known

as 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 lower-grade fuels. Similarly, high-grade

fuels, 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 your

Caterpillar dealer for informationregarding the use of these fueltypes.

Low Grade

Low-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-grade

fuel 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.

The high sulfur content oftenfound in low-grade fuels causescorrosion, wear and deposits in the

engine. 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 Grade

High-grade fuels burn cleaner, buthave a lower heat value, whichyields slightly less power. Aviation jet fuels and kerosene are consideredhigh-grade fuels and seldomcontribute to the formation ofharmful engine deposits andcorrosion. Other attributes of high-grade fuels include the benefits offaster engine starting and lessfrequent overhauls, and thedrawback of reduced lubricity.

American Society for Testing and

Materials (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





bunkering ports around the world.However, not all of the types areavailable at every station.

Gas Oil

This is a light distillate fuel whichdoes not contain any residual fuel.Gas oil is approximately ASTM No. 1diesel fuel.

Marine Diesel

This 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: ASTM

No. 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 Oil

This 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 Fuel

This 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 TypeFuels

Aircraft 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 Caterpillar

engine fuel systems, a minimumviscosity of 1.4 cSt at 38°C(100°F) is required at the enginetransfer pump to properly lubricatefuel system components. Kerosene

type 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.

Biodiesel

Biodiesel is a fuel that can be madefrom a variety of sources. Soybeanoil and rapeseed oil are the primary

sources, 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.





• Corrosion: A polished copperstrip is immersed in fuel forthree hours at 50°C (122°F).

Fuel imparting more thanslight discoloration is rejected.

Diesel Fuel Selection

The 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 which

meet Caterpillar requirements.

Standard Name Description

ASTMD975

No. 1-D & No. 2-DDiesel Fuel Oils

ASTMD396

No. 1 & No. 2 FuelOils

American

ASTMD2880

No. 1-GT & No. 2-GTGas Turbine Fuels

BS 2869Classes A1, A2 & B2

Engine FuelsBritish

BS 2869Classes C2 & D Burner

Fuels

DIN51601

Diesel FuelWest

German DIN51603

Heating Oil El

AustralianAS

3570Automotive Diesel

Fuel

JapaneseJIS

K2204Types 1 (spl), 1, 2, 3,

& 3 (spl) Gas Oil

W-F-

800C

DF-1, DF-2 Conus &

DF-20 Conus DieselFuelU.S.Government

W-F-815C

FS-1 & FS-2 BurnerFuel Oil

U.S.Military

MIL-L-16884G

Marine Oil

Table 1

Table 2 lists acceptable aircraft jetfuels and kerosene type fuels.

Name Description

ASTM D1655-80

Aviation Turbine Fuel(JET A-1)

MIL-T-5624LAviation Turbine Fuel

(JP-5)(NATO Code No. F-44)

MILT-T-83133B

Aviation Turbine Fuel(JP-8)

(NATO Code No. F-34)

Table 2





Diesel Fuel SystemsThe fuel system on a diesel engine is a highly specialized set of

components 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/Components

Caterpillar 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 CONTENTS

Basic 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 Design

Considerations• Fuel Transfer Systems

• Fuel Piping DesignConsiderations

• Fuel Filtration SystemsMiscellaneous

Considerations ...................30

• Fuel Temperature• Fuel Coolers

• Fuel Heaters• Burning Used Crankcase OilFuel Consumption

Practices ...........................36





Basic Fuel System

The 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 via

the 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 the

center 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 regulating

valve. 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 provide

the proper fuel pressure to theinjectors.

The manual fuel priming pump is

recommended 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 fuel

transfer 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 and

controlled 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





Control Module (ECM) to control theamount of fuel injected into thecylinders. A solenoid on eachinjector receives voltage signals fromthe ECM to become energized. The

injectors 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 a

common rail fuel system injectionpressure is created external to the

unit injectors in a high-pressure fuelpump which is driven off the engine.The pump pressurizes a high-pressure fuel manifold that runsalong both sides of the enginefeeding high pressure fuel to theinjectors. The electronic fuelinjectors at each cylinder control the

delivery and timing of the fuelinjection(s). Similar to some othersystems, the common rail fuelsystem has capability of multipleinjections for a given combustion

event.The main components of a

common rail system include thehigh-pressure pump, the high-pressure lines 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, it

is 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 the

injectors, more susceptible todamage from fuel contaminants andwear, hence the importance ofproper filtration practices oncommon rail engines.





ACERT TechnologyCaterpillar ACERT Technology

improves diesel engine performance.This technology provides precisecontrol over a range of combustion

variables, which can be regulated to

produce higher performance withfewer emissions. This newtechnology works with the MEUI,HEUI and Common Rail fuelsystems.

Fuel System Schematic

Figure 1





Common Rail System Schematic

Figure 2





Diesel Fuel System Design Considerations

Diesel 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 large

main storage tanks and transferred

to 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 Tank

The main fuel tank represents theprimary fuel reservoir in allapplications, and must haveadequate capacity for the intended

application. Rule of thumb for tanksize is to find the fuel consumptionrate at 100% load factor (depending

on 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) 3516B

diesel 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 L

Tank vol. = 75 x 168 x 1.1 = 12,600 gal





Installation Example with Main and Auxiliary Fuel Tanks

Figure 3

Auxiliary Fuel Tanks

Auxiliary fuel tanks, service tanksand day tanks are secondary fueltanks located between the main fuel

tank 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 fuel

injectors.Any of the above conditions can

cause unsatisfactory engine startingand operation. The purpose of anauxiliary tank is to relieve the fuel

pressure “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 while

providing a settling reservoir forwater, sediment and sludge. Anexample of an auxiliary fuel tank isshown in Figure 4.





Typical Auxiliary Fuel Tank

Figure 4

Fuel Service Tank or Day Tank

Auxiliary 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 vicinity

of 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 or

automatically 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.





• Fill line - Located above thehigh fuel level, with outletbaffled to prevent agitation ofsediment in the tank.

• Delivery line - Located near

the 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 tank

in event of overfilling of theauxiliary tank.• Vent line - Allows air pressure

to 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 on

fuel level.To prevent damage to the fuel

filter 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 a

flexible 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 the

fill line. To simplify enginemaintenance, a shut-off valve in thesupply line is useful.

The delivery line, carrying the fuelto the engine-mounted fuel transfer

pump, 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 the

sizes for each model.It is important that the fuel return

line 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 higher

than 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 lift

capability. 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.





Typical Fuel Head Limiting Tank

Figure 5

Fuel Head Limiting Tank

If 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. This

tank 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 only

purpose is to limit the head of fuelon the engine’s injection system.

Base Mounted Tanks

Base mounted day tanks aresometimes used to provide aconvenient and close source of fuelwith adequate capacity for four to

eight hours of operation. Whileminimizing the floor space neededfor fuel storage, the height of theengine will increase significantlywith this option designed to easemaintenance.





Fuel returning to the main tankmay, because of its volume, aid withcooling, but returning to the daytank is permissible.

Fuel Tank DesignConsiderations

Fuel Tank Sizing

The 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, as

outlined 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 Material

Fuel 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 Installation

Large 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 level

generally should not exceed theengine injector’s height. Thisprevents possible fuel leakage intocylinders.

Above ground tanks provide

accessibility, 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 also

avoided 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 for

convenience and safety of fillingoperations. Vents are necessary torelieve air pressure created by fillingand prevent vacuum as fuel isconsumed.

Fuel Tank Drains

All fuel tanks should have easilyaccessible drain connections. Waterand sediment that collects in thebottom of the tank must be

eliminated regularly. Provide clean-out openings for periodical removalof sediment and trash that settlesout of fuel tanks.

Well-designed tanks have largeenough clean-out openings so the





lowest part of the fuel tank can beaccessed with cleaning equipment.

Fuel Tank Grounding

Fuel 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 Maintenance

Fuel 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 and

pipes

• Swells rubber products that itcontacts

Sulfur 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.

Because 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 be

completely 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 are

designed 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,





between the day tank and engineexceeds the requirements discussedin Auxiliary Fuel Tanks. An example

of a fuel transfer system is shown inFigure 6.

Typical Fuel Transfer System

(Distillate Fuel Supply System)

Figure 6





Fuel Transfer Pumps

Engine Driven

Caterpillar 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 a

pump 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 elevation

gets greater, the atmosphericpressure decreases and theavailable lift will also decrease.Refer to Table 3.

ElevationAtmospheric

Pressure

Available

Lift

meters feet kPa psi meters feet

0 0 101.3 14.7 5.18 17.0

30.5 1000 98.0 14.2 4.87 16.0

61.0 2000 93.8 13.6 4.70 15.591.5 3000 90.3 13.1 4.57 15.0

122.0 4000 86.9 12.6 4.40 14.5

152.5 5000 83.4 12.1 4.26 14.0

183.0 6000 80.7 11.7 4.10 13.5

Table 3

Auxiliary

An auxiliary transfer pump is

required 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 is

needed 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.





In 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).

Emergency

Many marine applications requirethe capability to connect an

emergency 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 engine

applications. 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 operate

and the ship to reach port for enginerepairs.

Guidelines for emergency fuel oilsystem operation:

1. Keep pressure drops to aminimum by using short, low-restriction lines.

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 at

the 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 Design

Considerations

Fuel Supply PipingUsing shutoff valves in the delivery

line 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





should be timed to close after theengine stops rotating.

Pressure

The pressure measured in the fuelsupply line should be kept below thevalues shown in TMI.

Fuel Return Piping

Fuel 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 of

sorts, 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.

Pressure

Engine 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.

Purging

Purging should take place both inthe supply and the return line.

Siphoning & Check Valves

Siphoning 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 the

pump has been deactivated and thefuel supply line is breeched.

Material

Black 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 is





extremely harmful to the engine’sinternal components.

Pipes, hoses and fittings must bemechanically strong and resistant todeterioration due to age or

environmental 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.

Sizing

Sizing of pipes, hoses and fittingsmust be adequate to minimize flow

loss.

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 carrying

fuel 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 are

low, 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.

Routing

Fuel lines should be well routedand clipped with flexible hoseconnections where relative motion ispresent. Lines should be routed

away 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 lines

down 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 Caterpillar

fuel 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’s

minimum specifications willadversely affect:

• The perceived performance ofthe combustion system andfuel filters.





• The service life of the fuelinjection system, valves,pistons, rings, liners andbearings.

Even when fuel is handled very

carefully, 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 or

bypassed. The comparison in Figure7 demonstrates the very tightclearance in the fuel system and thesize of visible particles.

Sizes of Particles

Figure 7

Primary filters will extend enginefilter and transfer pump life. Waterand sediment traps can be includedupstream of the transfer pump, but

pump flow must not be restricted.

Filter Micron Ratings

Caterpillar 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 is

not 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 micron

rating 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 severe

drawback: 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:





• What is the maximum particlesize which can pass throughCaterpillar filters?

• What is the differencebetween nominal size and

absolute size filters?For example: A nominal 10 micron

filter 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 Element

Specification

The 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 Filters

Many Caterpillar Engines can beequipped with duplex fuel filters asshown in Figure 8.

Figure 8

These filters may be serviced(change elements), without shuttingoff the engine. There are two types:the symmetrical type, which hastwo identical filter sets and the

main-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.





• 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 Separation

Water 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 be

more prevalent in humid climates.Water can impact the fuel system

in 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 iron

oxide 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.





• Coalescing filter systems workeffectively to removesediment and water. If thelevel in the day tank is notmaintained at a consistent

level, 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.

Centrifuges

The 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 should

be consulted to determine the propercentrifuge type, size and flowrequirements for a specificapplication.

While Figure 9 shows a singlecentrifuge schematic, manyapplications will require the use of

two (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 t

Where:

Q= Flow required, L/hr

P= Total Engine Output, kW

b= Fuel Consumption, g/kW-hr

R= Density of fuel, kg/m3

T= Daily separating time inautomatic operation: 23 hr

Or:

f x be x 24 x 1.15Q =

R x t

Where:

Q= Flow required, gal/hrP= Total engine output, bhp

Be= Specific fuel consumption,lb/bhp-hr

R= Density of fuel, lb/gal

T= Daily separating time inautomatic operation: 23 hr

Note 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.





Typical Distillate Fuel Centrifuge

System

Figure 9

Centrifuge seal water and controlair requirements must be specifiedby the centrifuge manufacturer.

Sample Points

The centrifuge operating efficiencyis checked by drawing samples fromboth sides of the centrifuge.

Suction Strainer

Install 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 normally

manufactured from cast iron orbronze.

Centrifuge Supply Pump

Mount an electric motor drivensupply pump separately from thecentrifuge and size it appropriatelyfor the centrifuge flow. The

following pump characteristics areprovided for guidance:

• Operating pressure - to suitconditions of piping system

• Operating fluid temperature -38°C (100°F)





• Viscosity for sizing pumpmotor - 500 cSt

Centrifuge Fuel Heater

The heater is sized using the pumpcapacity and the temperature riserequired between the settling tankand the final centrifuge. The heater

should 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).





Miscellaneous Fuel System Considerations

Fuel TemperatureThe fuel temperature supplied to

the 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 Fuel

Temperature to the Low Pressure Fuel

Transfer Pump for Common Rail

Applications

C175 70°C (158°F)

C7, C9, C15, C18 80°C (176°F)

Table 4

The 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 is

operating below the fuel stop limit,the governor will add fuel asrequired to maintain the required

engine speed and power.

Fuel CoolersAs mentioned earlier in the Basic

Fuel 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, is

used 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 low

viscosity, 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 needs

to be done. If the stabilized fuel tanktemperature is high, the returningfuel should be cooled.

The following factors affect theneed for fuel cooling equipment.





• Length of periods ofcontinuous operation; If theoperating periods are short,the amount of heat returnedto the fuel tanks will be

relatively 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 supply

temperature. 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 shell

plating, 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.

ComponentSuggested

Material

Shell Red Brass

Heads Cast Iron

Tubes Copper Nickel

Tube Sheets Brass

Baffles Brass

Table 5

A 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 maintenance

procedures of fuel cooler in seawater applications.

Fuel HeatersJust as the ability to remove

excess 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





before 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 cloud

point 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 of

heaters 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.

• Heaters used should becapable of handling themaximum fuel flow of theengine. The restriction createdshould not exceed published

levels 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 temperature

rises 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.





Partial Load OperationExtended operation at low idle or

at reduced load may cause increasedoil consumption and carbon buildupin the cylinders. Carbon buildup

results 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 ecological

pressures, 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 be

necessary 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%. Premature

filter 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 supply

tank before new fuel is added(maintaining the 5% used oil-to-fuel ratio). This procedureshould normally providesufficient mixing. Failure toachieve adequate mixing willresult in premature filterplugging by slugs of undilutedoil.





• Filter or centrifuge used oilbefore putting it in the fueltanks to prevent prematurefuel filter plugging,accelerated wear, or plugging

of 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 used

crankcase 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 than

normal.

Continuous Blending

If the installation warrants, usedlubricating oil can be blended andused in the engine in a continuousmanner. The normal method uses a

centrifuge module similar to Figure9. The following informationdescribes this system.

Centrifuge No. 1

Engine 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. 2

Distillate fuel/oil mixture daytank iscontinually centrifuged.

Metering Pump

Adds up to 5% clean waste oil tothe distillate fuel (from the mainsupply tank) when the daytank lowlevel switch calls for more fuel.

Static Mixer

Runs 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.





Figure 10





Fuel Conservation Practices

Fuel costs typically represent thesingle highest operating costassociated with any diesel engine

application. 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 a

good 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 relatively

high load factors.• Do not increase fuel settings

to obtain more power.• Make sure all air hoses and

connections do not leak.Leaks keep the compressorworking unnecessarily.

• Make sure the turbocharger isturning freely so that properair-fuel ratio is maintained. A

clean 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 at

air cleaner condition.





Appendix 1

Day Tank Sizing (When

Day Tank Serves as a Heat

Sink)The fuel supply temperature must

be 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 day

tank (void tanks, cofferdams,vessel shell plating, etc.)

• Return fuel temperatureTank temperature calculation are

performed 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 third

step 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 the

heat 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 tank

size 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 the

day 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 is

required to perform the calculations:

• Engine model• Engine developed power (MCR

or CSR)

• Engine speed





• Brake specific fuelconsumption (bsfc)

• Initial day tank fueltemperature

• Storage tank fuel temperature

(Make-up)• Ambient air temperature• Day tank length, width, and

height

• 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 element

Day Tank Thermal Capacity

Calculation

Example:

• Application: Single mainengine

• Engine Model: 3612

• Rated Power: 4640 bhp (CSR)• Rated Speed: 900 rpm

• bsfc: 0.326 lb/bhp-hr• Initial Day Tank Fuel

Temperature = 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 be

replenished 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/min

2. 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 gpm

b. Fuel mass flow burn rate= MBR (lb/min)

= 3.55 gpm x 7.1 lb/gal

= 25.21 lb/min

3. Engine fuel return rate under fullload conditions:





a. Fuel return flow rate= qrtn (gal/min)

= Supply rate - burn rate

= 19.0 gpm - 3.55 gpm

= 15.45 gpm

b. Fuel return mass flow rate= Mrtn (lb/min)

= 15.45 gpm x 7.1 lb/gal

= 109.70 lb/min

4. ∆TENG of fuel = (Tsupply - Trtn)

Q∆TENG =

Mrtn x Cp

1252 Btu/min=

(109.70 lb/min x0.5 Btu/lb-°F)

= 22.83°F

5. 95% Capacity of Diesel Oil DayTank, (lb)Weight density (p) for #2 dieseloil = 52.42 lb/ft3

MDT = L x W x H x pDO = 12 ft x

8 ft x 8 ft x 52.42 lb/ft3 =40258.6 lb.

Step 1

Calculate 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 shown

below for this example. Refer toTable 6.

IncrementalTime (Min)

Tank FuelQuantity (lb)

Capacity(%)

0 40258.6 100.0

60 38746.0 96.2

120 37233.4 92.5

180 35720.8 88.7

240 34208.2 85.0300 32695.6 81.2

360 31183.0 77.5

420 29670.4 73.7

480 28157.8 69.9

540 26645.2 66.2

600 25132.6 62.4

660 23620.0 58.7

720 22107.4 54.9

Refill 40258.6 100.0

Table 6





Step 2

Calculate 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 for

previous 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/min

T = 60 min.

TDT(t -1) =Initial day tanktemperature is used forfirst iteration, 85°F

MRTN = 109.70 lb/min∆TENG = 22.83°F

MBR = 25.21 lb/min

[(40258.6 - (134.9)(60))(85)] + [(109.70)(60)(85 + 22.83)]Tmix = [40258.6 -(25.21)(60)]

Tmix = 88.9°F @ t = 60 min.





This calculation is repeated foreach increment (t).

Prepare a summary table as shownin Table 7 for each increment (t).

IncrementalTime (Min)

MixTemperature (°F)

0 85.0

60 88.9

120 92.9

180 97.1

240 101.5

300 106.1

360 110.9

420 116.0480 121.3

540 126.9

600 132.9

660 139.3

720 146.1

Refill

Table 7





Step 3

Calculate the height of fuelcontained in the day tank at t =incremental time step. Prepare asummary table for each time

increment (t) as shown in Table 8.

MDT H=

p x L x W

Where:

H = Height of fuel in the tank

MDT = Fuel contained in the daytank at each incremental time

stepp = 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) Height (ft)

0 8.0

60 7.7

120 7.4180 7.1

240 6.8

300 6.5

360 6.2

420 5.9

480 5.6

540 5.3

600 5.0

660 4.7

720 4.4

Refill 8.0

Table 8





time step. The resulting value for QTK is 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 60

QTK = 8283.6 Btu

Example b.:

QTK ∆ TDT =

MDT x Cp 8283.6 Btu

∆ TDT =(38746.0 lb) (0.5 Btu/lb °F)

∆ TDT = 0.43 °F (From atmosphere to day tank)

Example c.:

TDT = TMIX + ∆TDT

TDT = 88.9 °F + 0.43°F

TDT = 89.3 °F

This series of calculations is then repeated for the subsequent incrementaltime steps.





Prepare a summary table for each time increment (t) as shown in Table 9.

Incremental Time

(min)

Heat Rejection to/from

Day Tank (Btu)

Temperature Chg. in

Day Tank (°F)

Day Tank Temperature

(°F)

0 - - 85.0

60 8283.6 0.43 89.3

120 4069.7 0.22 93.2180 -4.0 0.00 97.1

240 -4022.0 -0.24 101.3

300 -7966.3 -0.49 105.6

360 -11818.7 -0.76 110.2

420 -15561.4 -1.05 114.9

480 -19257.8 -1.37 120.0

540 -22802.6 -1.71 125.2

600 -26253.3 -2.09 130.8

660 -29655.5 -2.51 136.8

720 -32973.6 -2.98 143.1Refill - - 116.9

Table 9

The 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 full

Where:

MDT full = Capacity of day tank, (lb)

MDT tn = Fuel in day tank prior to refilling, (lb)

TMUF = Temperature of make-up fuel, (°F)

TTK n = Temperature of tank fuel prior to refilling, (°F)

Example:

[(40258.6 - 22107.4) x 85] + (22107.4 x 143.1)TDT refill =

40258.6 lb

TDT refill = 116.9°F





Step 5

The 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 Table

10:

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 supply

temperature 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 - 10°F

X100 ]

Where:

Pcorr = Corrected Engine Power,bhp

Prated = Rated bhp

Tref = 86° (Power setting)

TDT = Actual day tank fueltemperature, °F

Example:

For t = 60, the corrected power ofthe engine is:

(89.3°F - 86°F) 1Pcorr = 4640 bhp x [1 -

10°FX

100 ]

Pcorr = 4625 bhp

IncrementalTime (min)

Day TankTemp. (°F)

CorrectedEngine Power

(bhp)

0 85.0 -

60 89.3 4625

120 93.2 4607

180 97.1 4588

240 101.3 4569

300 105.6 4549

360 110.2 4528

420 114.9 4506

480 120.0 4482

540 125.2 4458

600 130.8 4432

660 136.8 4405

720 143.1 4375

Refill 116.9 4497

Table 10

Conclusion

The previous calculations indicateday tank fuel temperatures can havean effect on the maximum power

capability 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 vessel

performance 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 the





injectors 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 the

beginning 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 the

fact that available engine power isstill acceptable.

Aside from the impact on engineperformance, maximum fuel tanktemperatures are also established by

various marine classificationsocieties and regulatory bodies.Their interest is based upon theincreased risks of fire that resultsfrom elevated fuel temperatures.

Useful Fuel Formulas and Data

The following information can be useful in sizing fuel coolers and heaters:

Specific Gravity (SG) and Density

API Gravity = (141.5/SG) - 131.5

SG = 141.5/(API Gravity + 131.5)

DensitySG =

998 kg/m3

Density (kg/m3) = SG x 998 kg/m3

1 lbm/ft3 1 ft3

Density (lbm/gal)= SG x 998 kg/m

3

x 16.02 kg/m3 x 7.48 gal

Mass Flow Rate

1m3 Flow Rate (L/min)M (kg/sec) = Density (kg/m3) x

1000 Lx

60 (sec/min)

M (lbm/min) = Density (lbm/gal) x Flow Rate (gal/min)





Specific Heat (cp)

Table 11 shows typical specific heat values for two different API gravityfuels in Btu/lbm-°F:

API Gravity38°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 0.530

40 0.477 0.497 0.516 0.526 0.546

Table 11

0.5461 Btu/lbm-°F = 4.186 kJ/kg-°C

Heat Rejection

Q (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)





Appendix 2

Crude Oil Fuel

Note: Crude oils are not suitable for

use 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 not

recommend 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 unsuitable

because 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 system

components and to permitsatisfactory starting capability.

The same diesel power ratings may

not 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 excessive

amounts 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 may

also 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





each situation requires anassessment. Jacket-water heatedfuel filters, available from fuelequipment suppliers, are oftensuitable for heating the crude. If

this 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, the

blending 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 of

crude 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, which

have low cetane numbers, shouldnot exceed 30% of the totalcrude. The kerosene, distillateand gas oil fractions combinedshould make up at least 30% of

the 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 float-type steam trap inverted, but it

should be made of corrosion-resistant materials. 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 in

each 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 to





avoid short oil changes. The useof Caterpillar S•O•SSM, is stronglyrecommended.

Crude Oil Maintenance

IntervalsEngine inspection intervals should

be 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 be

removed from crude oil by proper

settling. A recommended settlingsystem consists of two cone-bottomed tanks, 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 water

is 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 be

vented outside the building.A two-day supply of diesel fuel

should 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





Crude Oil Specification

Specification and ASTM Test Method Requirements

Cetane number (1) (ASTM D613)(DI Engines)

Minimum 40

Water and sediment % volume (ASTM Maximum 0.5%

Pour point (ASTM D97) Minimum 10°F (6°C) below ambient temperature

Cloud point (ASTM D97) MaximumNot higher than lowest expected ambienttemperature

Sulfur (ASTM D3605 or D1552) Maximum3% - See pages 131 & 132 to adjust oilTBN for sulfur content that is above 1%

Minimum 1.4 cSt

Kinematic Viscosity (2) Maximum

20 cSt (as delivered to rotary fuel injectionpumps)20 cSt (as delivered to other fuel injectionpumps)

API gravity (ASTM D287) MaximumMinimum

4530

Specific gravity (via Standards tables) (3) MaximumMinimum

0.80170.8762

Gasoline and naphtha fraction(fractions boiled off below 392°F (200°C))

Maximum 30%

Kerosene and distillate fraction (fractionsboiled off Minimum 30%

Carbon residue (on 10% bottoms) (ASTM Maximum 3.5%

Distillation - 10%- 90%- cracking

- residue (ASTM D86)

MaximumMaximumMinimum

Maximum

540°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 200

Gums and Resins (4) (ASTM D381) Maximum 5.8 grains per gallon (10 mg per 100 mL)

Copper strip corrosion (ASTM D130) Maximum No. 3

Flashpoint °F °C (ASTM D93) Minimum legal limit

Ash % weight (ASTM D482) Maximum 0.1%

Aromatics % (ASTM D1319) Maximum 35%

Vanadium PPM (ASTM D3605) Maximum 4 PPM

Sodium PPM (ASTM D3605) Maximum 10 PPM

Nickel PPM (ASTM D3605) Maximum 1 PPM

Aluminum PPM (ASTM D3605) Maximum 1 PPM

Silicon PPM (ASTM D3605) Maximum 1 PPM

PPM = 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 low





viscosity 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.





Reference MaterialThe following information is

provided as an additional referenceto subjects discussed in this manual.

SEBD0717Diesel Fuels and Your Engine

SEBU6251

Caterpillar Commercial DieselEngine Fluids Recommendations

SEBU7003

3600 Diesel Engine FluidsRecommendations for Lubricants,Fuels, and Coolants

REHS0104

Guidelines for 3600 Heavy Fuel Oil(HFO) Engines

SENR9620

Improving Component Durability:Fuel Systems

WECAP

Web Engineering Cataloging andProcuring website

Diesel Fuels and Diesel Fuel Systems

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