Diesel Fuels & Diesel Fuel Systems

APPLICATION AND INSTALLATION GUIDE

DIESEL FUELS & DIESEL FUEL SYSTEMS

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 ...... 4

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 ...... 17

Fuel Tank Maintenance...... 18

Fuel Transfer Systems...... 18

Fuel Transfer Pumps...... 19

Fuel Piping Design Considerations...... 21

Fuel Supply Piping...... 21

Fuel Return Piping ...... 21

Purging...... 22

Siphoning & Check Valves ...... 22

Material ...... 22

Sizing ...... 22

Routing...... 23

Fuel Filtration Systems ...... 23

Filter Micron Ratings ...... 24

Primary Fuel Filter Element Specification...... 24

Duplex Fuel Filters ...... 25

Water Separation ...... 25

Miscellaneous Fuel System Considerations...... 29

Fuel Temperature...... 29

Fuel Coolers ...... 29

Fuel Heaters...... 30

Partial Load Operation ...... 31

Burning Used Crankcase Oil ...... 31

Continuous Blending...... 33

Fuel Conservation Practices ...... 34

Appendix 1 ...... 35

Day Tank Sizing (When Day Tank Serves as a Heat Sink) ...... 35

Day Tank Calculations ...... 35

Day Tank Thermal Capacity Calculation ...... 36

Useful Fuel Formulas and Data ...... 44

Appendix 2 ...... 46

Crude Oil Fuel ...... 46

Pretreatment of Crude Oils...... 46

Crude Oil Maintenance Intervals ...... 48

Crude Oil Settling Tanks ...... 48

Reference Material...... 51

Foreword This section of the Application and Installation Guide generally describes Diesel Fuels and Diesel Fuel Systems for Cat® engines listed on the cover 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 additional references. Systems and components described in this guide may not be available or applicable for every engine.

Diesel Fuels & Diesel Fuel Systems Application and Installation Guide

Diesel Fuels Diesel fuel quality is an important factor in satisfactory engine life and performance. Fuels must provide adequate combustion without producing excess contaminates that can harm the engine. Additionally, fuel selection involves economic and environmental considerations. The availability of certain grades of diesel fuels may be cost prohibitive or inappropriate for various applications. This Application and Installation Guide provides information on the various diesel fuel oil types and how they relate to Cat engine installations.

SECTION CONTENTS

Common Diesel Fuel...... 2 Diesel Fuel Selection ...... 6  Diesel Fuel Grades  Diesel Fuel Types  Diesel Fuel Characteristics

Common Diesel Fuel

Diesel Fuel Grades The high sulfur content often found in low-grade fuels causes A variety of fuel oils, also known corrosion, wear and deposits in the as middle distillates, is marketed for engine. Fuels that are not volatile use in diesel engines. Their enough or don’t ignite rapidly may properties and performance depend leave harmful deposits in the engine upon the refining practices employed and may cause poor starting or and the nature of the crude oils from running under adverse operating which they are produced. Because conditions. The use of low-grade of constituents in the oil, some fuels may require the use of high crude oils are naturally suited for priced, higher detergent lubricating refinement into high-grade fuels oils and more frequent oil changes while others are best used for lower- to yield appropriate performance and grade fuels. Similarly, high-grade engine life. fuels, low-grade fuels and the various grades between them High Grade provide choices for the most suitable High-grade fuels burn cleaner, fuel for any given installation. but have a lower heat value, which Note: The use of very high-grade yields slightly less power. Aviation or very low-grade fuel oils often jet fuels and kerosene are considered requires modification to the fuel high-grade fuels and seldom system and special consideration contribute to the formation of of additional costs that may be harmful engine deposits and encountered. Contact your Cat corrosion. Other attributes of high- dealer for information regarding the grade fuels include the benefits of use of these fuel types. faster engine starting and less frequent overhauls, and the Low Grade drawback of reduced lubricity. Low-grade fuels produce a higher heat value which translates into American Society for Testing more engine power, but they also and Materials (ASTM) produce more contaminates that Due to the different engine could negatively impact engine-life. applications, designs and sizes, Additionally, the use of low-grade standards for the limits of fuel fuel oil in diesel engines often properties have been set by the produces darker exhaust and a more American Society for Testing and pronounced odor. These attributes Materials (ASTM). Utilizing the may be objectionable in hospital, correct fuel for the engine will office, commercial or urban settings minimize wear of the injection and require the use of a higher-grade system, allowing easier starting and fuel. improve component service life. Experience has proven that distillate fuels meeting basic

specifications will result in optimum deposit formations which can cause engine performance and durability. increased cylinder and ring wear. Depending on fuel costs and Blending may improve fuel density; availability, the proper use of alterna- however, adding alcohol (ethanol, tive fuels such as crude oil, blended methanol) or gasoline causes an oil or residual oil can also provide explosive atmosphere in the tank cost competitive engine operation. and is not recommended. Diesel Fuel Types Cat 3600/C280 diesel engines, in general EPG applications only, can be Crude Oil modified to run on blended fuels, but The term crude oil is used to extreme PREVENTIVE MEASURES describe petroleum-based oils/fuels MUST BE TAKEN, including following that are not yet refined. They are a thorough maintenance program and essentially in the same state as when use of high quality fuel treatment they were pumped from the earth. equipment. For any other applications Certain types of crude oils can be including marine, petroleum, industrial, burned in Cat engines. In some etc. that require the burning of blended cases, crude oil is a practical and fuels, MAK Engines should be economical fuel for diesel engines. considered. Crude oils are evaluated individually Blended fuel can lower fuel cost, and special equipment may be but there are often significant trade- needed to condition the fuel. offs. Fuel price must be weighed Minimum guidelines have been against the following. established to determine the suitability of crude oils as shown in  Fuel containment effects Appendix 2.  Reduced engine component life  Higher maintenance and Residual Oil or Blended Heavy Fuel personnel costs Oil (HFO)  Reduced warranty Residual fuel (which resembles tar and contains abrasive and corrosive Distillate Fuel substances) is composed of the Distillate fuels are refined from remaining elements from crude oil crude oil and are commonly referred after the crude has been refined into to as diesel fuel, furnace oil, gas oil, diesel fuel, gasoline, or lubricating or kerosene. oil. Marine Diesel Oil After the more desirable products Many different names are used for have been refined, residual fuel can marine diesel fuels, which can often be combined or diluted with a lighter cause a misunderstanding. Four fuel to produce a mixture that can types of marine diesel fuel are flow. This mixture is called blended generally recognized and available or heavy fuel. Heavy fuels tend to at bunkering ports around the world. create more combustion chamber However, not all of the types are available at every station.

Gas Oil components. Kerosene type fuels This is a light distillate fuel which have lower energy content than does not contain any residual fuel. diesel fuels and therefore will Gas oil is approximately ASTM No. 1 produce less peak power output diesel fuel. and/or will require more fuel volume to do an equivalent amount of work. Marine Diesel This is a distillate fuel that boils Biodiesel at a higher temperature than gas oil. Biodiesel is a fuel that can be made The fuel varies from ASTM No. 2 from a variety of sources. Soybean diesel fuel to ASTM No. 4 diesel oil and rapeseed oil are the primary fuel. The composition can vary sources, but alternate base stocks within the following range: ASTM may include animal tallow, waste No. 2 diesel fuel, No. 2 that is cooking oil, or a variety of other contaminated with heavier fuel in feedstocks. the bottom of the tanker, and In original forms, these oils are not No. 2 that is blended with as much suitable for use as a fuel in com- as 20 % residual fuel. pression engines; they must first be Blended Fuel Oil esterified. Without esterification, This is a blend of distillate and these oils will gel in the crankcase residual fuel. This fuel is blended to and the fuel tank. the viscosity that is requested by the Ultra Low Sulfur Diesel (ULSD) operator or the engine manufacturer. Ultra low sulfur diesel represents Blended fuel is not recommended for distillate fuels with ≤15 ppm sulfur. use in Cat engines that are It has been developed to reduce configured to use distillate fuel. particulate engine emissions. Residual Fuel This is residue from the distillation Diesel Fuel Characteristics of crude oil in a refinery. DO NOT The following information use residual fuel in Cat engines that describes the basic fuel are configured to use distillate fuel. characteristics and their relation to engine performance. Aircraft Jet Fuels and Kerosene Type  Cetane Number: Index of Fuels ignition quality determined by Aircraft jet fuels and kerosene type comparing with fuels used as fuels may be used as a diesel engine standards for high and low fuel provided they meet acceptable cetane numbers. The higher limits. Adequate viscosity, the cetane number is the particularly with kerosene type fuels shorter the ignition delay is a major concern. For Cat engine period which affects warm- fuel systems, a minimum viscosity up, combustion, cold start of 1.4 cSt at 38°C (100°F) is and exhaust smoke density. required at the engine transfer pump to properly lubricate fuel system

 Sulfur: Sulfur is an element  Flash Point: Lowest that occurs naturally in all temperature at which fuel will crude oils, and when burned give off sufficient vapor to in the combustion chamber, ignite when flame is applied. can form oxides of sulfur.  Pour Point: Is the temperature These can react with water which is 3°C (5°F) above the vapor to create sulfuric acid, temperature where the fuel which can cause severe just fails to flow or turns engine damage. High sulfur solid. content requires usage of high  Cloud Point: The temperature Total Base Number (TBN) oils at which a cloud or a haze or shortening of the oil change appears in the fuel. This will periods. happen when the temperature  Gravity: An index of weight of falls below the melting point a measured volume of fuel. of waxes or paraffins that Lower American Petroleum occur naturally in petroleum Institute (API) ratings indicate products. heavier fuel containing greater  Water and Sediment: heat content. Percentage by volume of  Viscosity: A time measure water and foreign material to resistance of flow. High removed by centrifuging. viscosities cause poor fuel  Carbon Residue: Percentage atomization thereby by weight of dry carbon decreasing combustion remaining when fuel is burned efficiency. Low viscosity may until no liquid remains. not provide adequate  Ash: Percentage by weight of lubrication to fuel system dirt, dust, sand, and other components. foreign matter remaining after  Distillation: This involves combustion. heating crude to relatively  Corrosion: A polished copper high temperatures. Vapor strip is immersed in fuel for drawn at various temperatures three hours at 50°C (122°F). produce fuels of different Fuel imparting more than types. Lighter fuels, such as slight discoloration is rejected. gasoline, are drawn off first and heavier fuels last. It has an influence on viscosity of the fuel and the BTU content, which affects exhaust and smoke, starting and power output.

Diesel Fuel Selection Fuel should always be selected Table 2 lists acceptable aircraft jet based on the requirements set forth fuels and kerosene type fuels. in the Engine specific Operation and Maintenance Manual. The information and charts below are Name Description for reference only. The fuels ASTM D Aviation Turbine Fuel recommended for use in Cat diesel 1655-80 (JET A-1) engines are normally No. 2-D diesel Aviation Turbine Fuel fuel and No. 2 fuel oil, although MIL-T-5624L (JP-5) No. 1 grades are also acceptable. (NATO Code No. F-44) Aviation Turbine Fuel Table 1 lists the worldwide fuel MILT-T- (JP-8) 83133B standards which meet Caterpillar (NATO Code No. F-34) requirements. Table 2

Standard Name Description ASTM No. 1-D & No. 2-D D975 Diesel Fuel Oils ASTM No. 1 & No. 2 Fuel American D396 Oils ASTM No. 1-GT & No. 2-GT D2880 Gas Turbine Fuels Classes A1, A2 & B2 BS 2869 Engine Fuels British Classes C2 & D Burner BS 2869 Fuels DIN Diesel Fuel West 51601 German DIN Heating Oil El 51603 AS Automotive Diesel Australian 3570 Fuel JIS Types 1 (spl), 1, 2, 3, Japanese K2204 & 3 (spl) Gas Oil DF-1, DF-2 Conus & W-F- DF-20 Conus Diesel U.S. 800C Fuel Government W-F- FS-1 & FS-2 Burner 815C Fuel Oil U.S. MIL-L- Marine Oil Military 16884G Table 1

Diesel Fuel Systems The fuel system on a diesel engine is a highly specialized set of components which must deliver the correct amount of fuel to the cylinder at the precise moment it is needed. A well-designed fuel system enables the engine to produce maximum power at maximum efficiency with a minimum of exhaust emissions. Today’s diesel injectors must develop very high injection pressures to function with modern high compression ratio engine designs. They must also control the start and duration of injection within milliseconds to perform at the level demanded by engine customers. These precision injectors require an adequate supply of clean, stable fuel for proper operation. This requirement in turn demands careful attention to the fuel storage and handling systems specified for each installation. This section discusses the various fuel systems available on current Cat diesel engines, details the numerous fuel storage and handling system options available for diesel fuels, and outlines the advantages, disadvantages, and special considerations which accompany each system. Diesel Engine Fuel System Descriptions/Components Cat diesel engines are all furnished with a fuel system based on a conventional design, utilizing unit injectors, but with differing means of injector actuation and control. The following sections briefly describe the basic fuel system and the three types of injector control systems currently in use.

SECTION CONTENTS

Basic Fuel System...... 8  Fuel Piping Design  MUI Fuel System Considerations  MEUI Fuel System  Fuel Filtration Systems  HEUI Fuel System Miscellaneous  Common Rail Fuel System Considerations ...... 29  ACERT™ Technology  Fuel Temperature Design Considerations ...... 12  Fuel Coolers  Fuel Storage Systems  Fuel Heaters  Fuel Tank Design  Burning Used Crankcase Oil Considerations Fuel Consumption  Fuel Transfer Systems Practices ...... 34

Basic Fuel System The basic fuel system, common the proper fuel pressure to the to all Cat diesel engines, includes injectors. an engine driven fuel transfer pump, The manual fuel priming pump is a secondary fuel filter, unit fuel recommended if no electrical priming injectors and a fuel pressure pump is available. The manual pump regulator. Optional Caterpillar helps to bleed air from the fuel supplied fuel system components piping before initial engine operation include flexible hoses, a manual fuel and following engine maintenance priming pump, and a duplex primary such as filter element changes and fuel strainer. A basic fuel system injector replacement. schematic is shown in Figure 1. Caterpillar also recommends the The engine driven transfer pump use of a duplex primary fuel filter delivers fuel to the unit injectors via prior to the engine driven fuel the secondary fuel filter. The pump transfer pump. This filter is available is equipped with a pump-mounted from Caterpillar via custom quote. safety valve and the fuel flow at When used, the duplex primary fuel rated rpm is listed in the technical filter is installed, remotely from the data and varies with engine speed. engine, in the fuel transfer pump The unit injector, either suction piping. mechanically or hydraulically actuated, combines the functions of MUI Fuel System pumping, metering and injecting into The Mechanically actuated and a single unit. It is located near the controlled Unit Injectors (MUI) use center of the combustion chamber in the engine camshaft and push rods each cylinder head, between the to generate fuel injection pressure, rocker arms. External manifolds and a mechanical linkage system to supply fuel from the transfer pump control the amount of fuel injected to the injectors, eliminating the need into the cylinders. The mechanical for high pressure fuel lines. Fuel linkage system connects the continuously circulates through the governor to the fuel rack, which injectors, and the excess fuel that is allows the fuel rate to the engine not used for combustion cools the to be controlled in relation to the injectors and is returned to the fuel varying engine loads. tank via the pressure regulating MEUI Fuel System valve. This excess fuel also aids in The Mechanically actuated the purging of air from the system. Electronically controlled Unit The fuel delivery pressure to the Injectors (MEUI), formerly known as injectors is controlled by a pressure Electronic Unit Injectors (EUI), also regulating valve. The pressure use the engine camshaft and push regulator must be adjusted at the rods to generate fuel injection installation site in order to provide pressure, but use an Electronic

Control Module (ECM) to control the delivery and timing of the fuel amount of fuel injected into the injection(s). Similar to some other cylinders. A solenoid on each systems, the common rail fuel injector receives voltage signals from system has capability of multiple the ECM to become energized. The injections for a given combustion injectors will inject fuel only while event. the injector solenoid is energized. The main components of a The ECM controls the amount of common rail system include the fuel that is injected by varying the high-pressure pump, the high- signals that are sent to the injectors. pressure lines and rail system, and By controlling the timing and the the injectors. The low-pressure fuel duration of the voltage signal, the system utilizes similar components ECM can control injection timing and to the unit injector fuel system. See the amount of fuel that is injected. Figure 2 for a schematic of the common rail fuel system. HEUI Fuel System The common rail fuel system does The Hydraulically actuated not continually circulate fuel through Electronically controlled Unit the entire system like the unit Injectors (HEUI) use a hydraulic injector fuel system. Instead, small pump and engine oil to generate fuel amounts of fuel are bypassed during injection pressure, and an ECM to the injection event. Due to the very control the pressure and amount of high pressure in the fuel manifold, fuel injected into the cylinders. more heat is put into the fuel than The operation of the HEUI fuel on previous systems. Because of the system is completely different from additional heat added to the fuel, it any other type of fuel system that is is critical that the fuel inlet actuated mechanically. The HEUI temperature is maintained within fuel system is completely free of guidelines provided for the engine adjustment. Changes in performance model. Recommended, and are made by installing different sometimes required, is the use software in the ECM. of a fuel cooler to maintain the appropriate inlet fuel temperature. Common Rail Fuel System Otherwise, the overheated fuel will Unlike the MEUI fuel system, in a have very low viscosity and film common rail fuel system injection strength which makes the fuel pressure is created external to the system components, especially the unit injectors in a high-pressure fuel injectors, more susceptible to pump which is driven off the engine. damage from fuel contaminants and The pump pressurizes a high- wear, hence the importance of pressure fuel manifold that runs proper filtration practices on along both sides of the engine common rail engines. feeding high pressure fuel to the injectors. The electronic fuel injectors at each cylinder control the

ACERT Technology fewer emissions. This new technology works with the MEUI, Caterpillar ACERT Technology HEUI and Common Rail fuel improves diesel engine performance. systems. This technology provides precise control over a range of combustion variables, which can be regulated to produce higher performance with

Fuel System Schematic

Figure 1

Common Rail System Schematic

Figure 2

Diesel Fuel System Design Considerations Diesel fuel supply systems must application. Rule of thumb for tank ensure continuous and clean supply size is to find the fuel consumption of fuel to the engine’s fuel system. rate at 100% load factor (depending The recommended diesel fuel supply on application: Prime, stand-by etc.) system typically has three major and multiply it with the number of components: a fuel storage system, hours between refills. Fuel a fuel transfer system and a fuel consumption rates are shown on the filtration system. The three Engine Technical Data Sheets for the component systems provide clean specific engine. Additionally, 10% operating fuel to the engine. should be added to the result; 5% for expansion at the top of the tank, Fuel Storage Systems and 5% for sediment settlements at Bulk fuel is usually stored in large the bottom. main storage tanks and transferred to smaller auxiliary tanks (service Example: tanks or day tanks) near engines by A power plant with one (1) 3516B electric motor-driven pumps as diesel generator set, rated for shown in Figure 3. 1145 bkW (1560 bhp) at 100% load. The fuel rate for the engine is If auxiliary tanks are not 284 L/hr (75 G/hr) as found in TMI. necessary, the main fuel tank must provide a ready fuel supply to the The time between tank refills is engine-mounted transfer pump. based on weekly fuel tanker truck deliveries, so refill time is 168 hours. Main Fuel Tank The main fuel tank represents Solution: the primary fuel reservoir in all Tank vol. = 284 x 168 x 1.1 = 52,583 L applications, and must have Tank vol. = 75 x 168 x 1.1 = 12,600 gal adequate capacity for the intended

Installation Example with Main and Auxiliary Fuel Tanks

Figure 3

Auxiliary Fuel Tanks and operation. The purpose of an Note: Additional clarification is auxiliary tank is to relieve the fuel needed for C175. Reference TMI pressure “head” from the fuel and the special instructions transfer pump and injection REHS4726. equipment for efficient fuel flow. Auxiliary fuel tanks, service tanks A manual fuel priming pump, and day tanks are secondary fuel offered as an attachment, or an tanks located between the main fuel electric motor-driver boost pump tank and the engine. These tanks are may allow operation under required in the following situations. conditions more severe than those previously described; but where  The main fuel tank is located starting dependability is required, on the same level but more Caterpillar recommends the use of than 15 m (50 ft) away. an auxiliary fuel tank.  The main fuel tank is located 3.7 m (12 ft) or more below Auxiliary tanks offer convenient the engine. and ready fuel storage while  The main fuel tank is located providing a settling reservoir for above the engine fuel water, sediment and sludge. An injectors. example of an auxiliary fuel tank Any of the above conditions can is shown in Figure 4. cause unsatisfactory engine starting

Typical Auxiliary Fuel Tank

Figure 4

Fuel Service Tank or Day Tank usually employed using a float- Auxiliary tanks such as fuel service actuated, electric motor-drive pump. tanks or day tanks can be quite The refilling pump can be positioned simple. It usually consists of a small either at the auxiliary tank or at the metal tank, either floor or wall main tank outlet. The performance mounted, in the immediate vicinity capability of the pump must be of the engine. The tank is usually considered during placement. sized to hold approximately eight Features of the auxiliary tank, as hours of fuel, based on the engine’s shown in Figure 5, should include fuel consumption rate at full load. the following. Refilling can be accomplished by  Fill line - Located above the gravity, a hand pump, or with a high fuel level, with outlet motor-drive pump. Motor-drive baffled to prevent agitation of pumps can be either manually or sediment in the tank. automatically controlled. For convenience and safety, automatic control is

 Delivery line - Located near pump, and the return line, carrying the bottom but not so low as excess fuel back to the tank, should to pick up collected sediment be no smaller in size than the or condensation. respective fittings on the engine.  Return line - To carry excess Larger fuel supply and return lines fuel back to the auxiliary tank. ensure adequate flow if the fuel tank Should have its outlet baffled supplies multiple engines over 9 m for the reason described above. (30 ft.) away from the tank or when  Overflow line - Allows excess temperatures are low. Consult fuel to return to the main tank general dimension drawings for the in event of overfilling of the sizes for each model. auxiliary tank. It is important that the fuel return  Vent line - Allows air pressure line is sloped down to the tank with to equalize as tank is drained no traps or obstructions in the line. or filled (vent cap should be If this is not done, the fuel system is located away from open flame prone to air-lock with consequent or sparks). hard-starting.  Drain valve - Allows removal of condensate and sediment. The auxiliary tank should be located  Sight glass or float-type gauge so that should be close enough the - Provides a positive check on level of the fuel when the tank is full fuel level. is no higher than the injection To prevent damage to the fuel valves. On electronic unit injector filter housings, the return line should fuel systems, static pressure on the have no valves or restrictions to fuel system will cause fuel to leak allow dangerous pressure buildups. from the injectors leading to excessive fuel dilution of the engine Flexible rubber hoses, used as fuel oil. Static pressure would allow fuel return lines, should be supported to to leak into the combustion prevent closing off over time due to chambers in the event of injection weight of the hose and fuel. Hard valve leakage. The tank to the engine fuel lines prevent this problem, but a so that the total suction lift to the flexible connection is still required to transfer pump with the fuel at low isolate vibration between the line and level, plus the line loss of the supply the tank. line, is less than the fuel pump’s A nonflammable tank mounting will maximum suction lift capability. This maximize fire protection. figure should be minimized for better The overflow line should be at least starting. A float valve or solenoid valve two pipe sizes larger than the fill line. in this type of day tank regulates the To simplify engine maintenance, a fuel level to keep it below the level of shut-off valve in the supply line is the injectors. useful. Note: For C175 installations that are The delivery line, carrying the fuel set up such that excess fuel from to the engine-mounted fuel transfer the engine returns to the main tank

©2013 Caterpillar All rights reserved. Page 15 Application and Installation Guide Diesel Fuels & Diesel Fuel Systems and also require the fuel supply day required to be installed in the return tank to be located higher than the line to prevent fuel drainage and loss main tank, a check valve may be of prime. Reference REHS4726.

Typical Fuel Head Limiting Tank

Figure 5

Fuel Head Limiting Tank adequate capacity for four to eight If overhead mounting is hours of operation. While minimizing unavoidable, include an open/close the floor space needed for fuel solenoid shut off valve in the supply storage, the height of the engine will line and a 3.45 kPa (0.5psi) check increase significantly with this option designed to ease maintenance. valve in the return line. Be sure return restriction does not exceed Fuel returning to the main tank 350kPa (51psi) at speed and load. may, because of its volume, aid with cooling, but returning to the day Base Mounted Tanks tank is permissible. Base mounted day tanks are sometimes used to provide a convenient and close source of fuel with

Fuel Tank Design the danger of ground water Considerations contamination. Underground tanks allow the earth Fuel Tank Sizing to work as an insulator, limiting The fuel tank is typically one of the radical temperature changes which least expensive items in an installation, can cause flow restrictions, and it is wise to provide too much, condensation, and possible power rather than too little, storage capacity. loss. Seasonal settlings are also However, while the minimum required avoided when burying the tank capacities of fuel tanks can be below frost line. In underground estimated, as outlined in the previous tanks, the water must be removed discussion of fuel tanks, some by pumping through a tube placed applications may need to meet the down the fill pipe. requirements of outside organizations, such as the U.S. National Electrical Regulations governing the installation Code (NEC) or National Fire Protection and maintenance of both above and Association (NFPA). below ground fuel tanks may apply. Fuel Tank Material Locate storage tank fill tubes for Fuel tanks made from low carbon convenience and safety of filling rolled steel are best. operations. Vents are necessary to relieve air pressure created by filling CAUTION: Zinc, either in the form and prevent vacuum as fuel is of plating or as a major alloying consumed. component, should not be used with diesel fuels. Zinc is unstable in the Fuel Tank Drains presence of sulfur, particularly if All fuel tanks should have easily moisture is present in the fuel. The accessible drain connections. Water sludge formed by chemical action is and sediment that collects in the extremely harmful to the engine’s bottom of the tank must be internal components. eliminated regularly. Provide clean- out openings for periodical removal Fuel Tank Installation of sediment and trash that settles Large capacity storage tanks allow out of fuel tanks. bulk purchases and minimize dirt contamination. Maintaining full tanks Well-designed tanks have large reduces condensation, particularly if enough clean-out openings so the fuel is seldom used. lowest part of the fuel tank can be accessed with cleaning equipment. Tanks may be above or below ground level, but high fuel level Fuel Tank Grounding generally should not exceed the Fuel tanks, both bulk and auxiliary, engine injector’s height. This prevents need to be grounded. This is to possible fuel leakage into cylinders. improve personal safety and reduce the fire hazard of sparks discharged Above ground tanks provide from static electricity build-up during accessibility, allowing for easy refueling operations. draining of impurities and reducing

If the auxiliary tank is mounted to growth. Consult your local fuel the base of the engine, it will be supplier for recommended additives. grounded at the same time as the In warm climates, large bulk storage engine. If the fuel tank is placed diesel fuel requires full filtering every away from the engine, the tank six months to one year. must be grounded separately. Every two years the fuel should be Fuel Tank Maintenance completely changed to remove water, Fuel has a storage life of approx- scale, bacteria growth, oxidized imately one year. This period may gums/resins, and minimize filter vary widely depending upon initial clogging due to fuel separation into fuel quality, contaminant levels and components such as asphaltenes. storage conditions. To remove water, scale and Fuel Transfer Systems bacteria growth, periodic exchange Note: For C175 installations please of fuel and filtering/treating is review REHS4726. recommended to extend fuel life. The diesel engine fuel supply, Water contamination of fuel during delivery and governing systems are long-term storage provides a medium designed to deliver clean fuel in the for bacterial growth, forming a dark precise quantity and time needed to slime which: produce the required engine performance.  Plugs filters  Deposits on tank walls and All connection lines, valves and pipes tanks should be thoroughly cleaned  Swells rubber products that before making final connections to it contacts the engine. The entire fuel system external to the engine should be Sulfur compounds are natural antioxidants, so low sulfur fuels flushed prior to connection to engine and startup. (0.05 percent by weight) degrade quicker in storage. Caterpillar supplies the engine with Diesel fuels oxidize and form gums a transfer pump and the secondary filter. The customer must provide the and varnishes which can plug fuel filters and injectors. primary filter and, if needed, an auxiliary transfer pump. The auxiliary Because microorganism growth transfer pump is required when the occurs in the fuel/water layer, the distance, vertically or horizontally, tank should be designed to minimize between the day tank and engine this interface, and water bottoms exceeds the requirements discussed should be drained regularly. in Auxiliary Fuel Tanks. An example Microbiocide additives, either of a fuel transfer system is shown in water or fuel soluble, can be added Figure 6. to fresh fuel to inhibit microorganism

Typical Fuel Transfer System (Distillate Fuel Supply System)

Figure 6

Fuel Transfer Pumps To determine if a pump can Engine Driven perform the required lift, the following items must be considered. Cat engine-mounted transfer pumps are positive displacement 1. The vertical distance from the gear-type or piston-type pumps, with tank to the pump. The distance a limited prime and lift capability. should be measured from the The pump lifts the fuel by inlet pump port of the pump to the bottom of the tank. displacing air from the suction pipe to the discharge pipe. Low pressure 2. Internal piping system losses (vacuum) develops in the suction reduce the lifting capability. This pipe and atmospheric pressure is based primarily on the size and [101 kPa (14.5 psi) at sea level] the total length of the pipes, but moves the fuel into the vacuum. also includes the various fittings However, a perfect vacuum cannot and valves. As the temperature be maintained, and the maximum goes down the resistance goes that a pump can lift is about up. The internal losses can be 5 m (17 ft). estimated using the Piping Cat fuel pumps’ prime and lift System Basic Information section capability is 3.7 m (12 ft), but pipe of the Application & Installation Guide. size, routing, and ambient temperature will impact this 3. Elevation has a big impact on the capability. pump’s lifting capability. As

described above the atmospheric Note: For C175, primary fuel filters pressure is helping the fuel into are standard. the vacuum, but as the elevation In many cases, the auxiliary pump gets greater, the atmospheric will be driven by an electric motor pressure decreases and the and therefore needs a regulator available lift will also decrease. valve so that the fuel flow can Refer to Table 3. match the engine speed. Note: This table does not apply to Example: C175. Reference instructions in A power plant with one (1) 3516B REHS4726. diesel generator set, rated for 1145 bkW (1560 bhp) at 100% Atmospheric Available load. The fuel rate for the engine is Elevation Pressure Lift 284 L/hr (75 G/hr) as found in TMI. meters feet kPa psi meters feet The time between tank refills is 0 0 101.3 14.7 5.18 17.0 based on weekly fuel tanker truck 305 1000 98.0 14.2 4.87 16.0 deliveries, so refill time is 168 hours. 610 2000 93.8 13.6 4.70 15.5 915 3000 90.3 13.1 4.57 15.0 The fuel tank for this genset is 1220 4000 86.9 12.6 4.40 14.5 located 22 m (72.2 ft) horizontally 1525 5000 83.4 12.1 4.26 14.0 and 2.5 m (8.2 ft) vertically (below) 1830 6000 80.7 11.7 4.10 13.5 from the engine. This situation exceeds the fuel system Table 3 requirements discussed in Auxiliary Auxiliary Fuel Tanks, therefore, an auxiliary An auxiliary transfer pump is pump is needed. required when the service tank or Solution: day tank is located further away, TMI indicates that the fuel flow at horizontally or vertically, than the rated speed is 1260 L/hr (333 G/hr) engine driven pump’s lift capability. @ 1200 rpm. Special considerations must be The auxiliary transfer pump given to the auxiliary transfer pump required for this sample installation when dealing with electronic engines must be able to deliver fuel at and the 3500 engine family. Refer to 1260 L/hr (333 G/hr) at a pressure technical data for the engine's fuel of 34.5 kPa (5 psi). pump capacity to determine sizing Emergency auxiliary fuel transfer pumps. Many marine applications require A primary filter must be installed the capability to connect an before the auxiliary pump and as emergency fuel oil transfer pump close as possible to the tank. into the engine’s fuel oil system. Cat engines can be provided with these optional connections when necessary.

This is a specific requirement of is specified in the supply line, it marine classification societies for should be timed to close after the seagoing single propulsion engine engine stops rotating. applications. The purpose is to Pressure ensure fuel oil supply in the event of The pressure measured in the fuel an engine fuel oil pump failure. The supply line should be kept below the emergency fuel oil pump allows the values shown in TMI. single propulsion engine to operate and the ship to reach port for engine Fuel Return Piping repairs. Fuel return piping should normally enter the tank at the top and extend Guidelines for emergency fuel oil downward, exiting above the fuel system operation: level. Inlet and return lines should be 1. Keep pressure drops to a separated in the tank as far apart as minimum by using short, low- possible to allow fuel warmed in the restriction lines. engine to dissipate excess heat. Fuel 2. Use a line size at least as large tanks can function as a radiator of as the engine connection point. sorts, especially in engines that are 3. Install a low-restriction strainer in not equipped with a fuel cooler or front of the emergency oil pump. engines that use fuel to cool the injectors. Placing return lines and 4. Install a low-restriction check suction lines as far apart as possible valve between the emergency provides the most opportunity for pump discharge and the engine cooling. Return line placement is inlet connection. particularly important on smaller 5. Use a pressure-limiting valve in tanks and day tanks where the fuel the emergency system set at the volume is allowed to run down. maximum oil pressure limit of the The fuel return line is under engine. pressure, although not as high as the 6. TMI contains flow rates and supply line. pressure limits to fulfill minimum Note: Shut-off valves should not be engine requirements for full used in fuel return lines. Engine power at rated speeds for Cat operation with the valve closed will engines. cause damaging pressures. Fuel Piping Design Pressure Considerations Engine fuel pressure measured in the fuel return line should be kept Fuel Supply Piping below 27 kPa (4 psi), except for the Using shutoff valves in the delivery 3300 engine family, which is 20 kPa line may pull air into the system (3 psi), C175 engine family, which is during shutdown and cause hard 60 kPa (8.7 psi) and the 3600 or starting. The engine control system C280 family, which is 350 kPa provides adequate shutdown (51psi). The location of the day tank options, but, if a shutdown solenoid

and the design of the pipes should the fuel. The sludge formed by accommodate these requirements. chemical action is extremely harmful Purging to the engine’s internal components. Purging should take place both in Pipes, hoses and fittings must be the supply and the return line. mechanically strong and resistant to deterioration due to age or Siphoning & Check Valves environmental conditions. They must Siphoning can occur in full fuel also be airtight to avoid entry of air pipes when the one end of the pipe into the suction side of the fuel is placed in the fuel and the other system. A joint, which is leak-tight end is below the level of fuel. to fuel, can sometimes allow air to Siphoning is a flow of fuel in the enter the fuel system, causing pipe without the help of pumps. It erratic running and loss of power. can occur in supply and return lines. Siphoning is most likely to occur Sizing after a fuel line failure, which can be Sizing of pipes, hoses and fittings due to corrosion, fire or a cut from must be adequate to minimize flow foreign objects or collision force. loss. The consequences of fuel line Sizing for a particular application is siphoning are fuel loss and the determined by the supply and return creation of a fire hazard. If the fuel line restrictions. This can be ignites and the flow is not stopped, estimated with help from the Piping the fire will be more difficult to System Basic Information section of extinguish. the Application & Installation Guide. The maximum allowable restrictions The fuel supply line has a fuel are published in the TMI. transfer pump. To avoid siphoning, the pump must be equipped with Generally, the supply line carrying a check valve. This is in case the fuel to the fuel transfer pump and pump has been deactivated and the the return line carrying excess fuel fuel supply line is breeched. For back to the tank should be no certain C175 installations, a check smaller in size than the connection valve may be necessary. Reference fittings on the engine. In addition, page 15. the return line should be at least as large as the supply line. Material If the fuel tank supplies multiple Black iron pipe is best suited for engines over 9.14 m (30 ft) from the diesel fuel lines. Steel or cast iron tank, or ambient temperatures are valves and fittings are preffered. low, larger fuel supply and return CAUTION: Copper and Zinc, either in lines should be considered to ensure the form of plating or as a major adequate flow. The overflow line alloying component, should not be from the day tank (or, if no day tank used with diesel fuels. Zinc is is used, the engine fuel return line) unstable in the presence of sulfur, particularly if moisture is present in

©2013 Caterpillar Page 22 All rights reserved. Diesel Fuels & Diesel Fuel Systems Application and Installation Guide should be one size larger than the specifications as described in supply and return lines. SEBU 6251 will adversely affect: Routing  The perceived performance of Fuel lines should be well routed the combustion system and and clipped with flexible hose fuel filters. connections where relative motion is  The service life of the fuel present. Lines should be routed injection system, valves, away from hot surfaces, like pistons, rings, liners and manifolds and turbochargers, to bearings. avoid fuel heating and potential Even when fuel is handled very hazard if a fuel line should fail. carefully, foreign particles will find Fuel lines should be routed to avoid their way in during handling or formation of traps, which can catch storage. Foreign particles could be sediments, or pockets of water, paint flakes, dust, sand, rust or which will freeze in cold weather. microbiologic particles. Whenever possible, route fuel lines Clean fuel is necessary for depend- down low, so any potential leakage able engine performance. Engine will be confined to the fuel tank base filters protect the fuel injection pumps or floor space. Leaks from overhead and nozzles and should never be fuel system components may fall onto removed or bypassed. The compare- hot machinery, increasing the ison in Figure 7 demonstrates the very likelihood of fire danger. tight clearance in the fuel system and the size of visible particles. Route fuel lines to avoid crossing paths and walkways. Protect fuel Sizes of Particles lines from abrasion and damage. Whenever possible, route fuel lines so they are visible for leak checking. For electronic unit injector fuel systems, supply line pressure must decay to atmospheric pressure after engine shut down. Any sustained static pressure on the fuel system when the engine is not operating will cause excessive fuel to oil dilution. Figure 7 Fuel Filtration Systems Clean fuel that meets Caterpillar Primary filters will extend engine fuel recommendations provides filter and transfer pump life. Water outstanding engine service life and and sediment traps can be included performance. The use of lesser fuels upstream of the transfer pump, but is a compromise and the risk is the pump flow must not be restricted. user’s responsibility. Fuels not meeting Caterpillar's minimum

Filter Micron Ratings the paper needs to be balanced Caterpillar specifies actual filter against the costs of the filter capability, rupture strength, the replacements. capacity for holding dirt, flow Common questions are: resistance, filter area, etc.  What is the maximum particle Caterpillar does not specify filter or size which can pass through filter paper by micron rating. Micron Cat filters? ratings are easily confused for the  What is the difference following reasons: between nominal size and  The test for micron ratings is absolute size filters? not repeatable at different For example: A nominal 10 micron labs. One manufacturer may filter media (paper) will pass some give a rating of 10 microns particles up to about 50 microns in (0.00039 in.), another at size. Theoretically, an absolute rating 2 microns (0.000079 in.) and of 10 microns will stop all particles a third may rate a particular larger than 10 microns. In fact, filters filter media (paper) at with absolute micron ratings of 10 15 microns (0.00059 in.). will pass some particles larger than  There is no consistent 10 microns due to the irregularity of relationship between micron the paper weave. New filters may rating and actual filtration pass larger particles than they will efficiency. The entire filter after only a few hours of use. needs to be tested, not just As a rule, Caterpillar fuel filter media the media (paper). (paper) is about 3 microns nominal,  The micron rating does not 20 microns absolute. Oil filter media show what happens to a filter (paper) is about 10 microns nominal, over time. The test provides 50 microns absolute. These are no information about how a approximate values only. filter will stand up under Filters are not effectively compared continual use. on the basis of micron rating alone. Micron ratings are overemphasized; Evaluate filters on the basis of their a 10-micron filter will not always stop ability to collect foreign material as a 10-micron particle. Many reputable a whole. filter manufacturing firms are drifting away from micron ratings to more Primary Fuel Filter Element conclusive tests. Smaller micron Specification ratings are not necessarily better. The specs for primary fuel system If all other factors (area) were elements are as below: equal, a smaller micron number  10 Micron Nominal Filtration media (paper) has a severe draw-  For additional information see back: it has less capacity before SENR9620 Fuel Systems - plugging and needs to be replaced Improving Component more often. The size of the pores in Durability

Duplex Fuel Filters  Generally, the same elements Many Cat engines can be equipped are used in both systems, and with duplex fuel filters as shown in are capable of providing Figure 8. adequate filtration for at least 100 hours full load running time with reasonably clean fuel and oil.  Use pressure gauges to determine when filters must be changed.  Avoid mounting filters near the radiator fan, because a fuel or oil leak during replacement could create Figure 8 a fire hazard. (As either substance passes through the These filters may be serviced fan it can be atomized, and (change elements), without shutting therefore easier to ignite.) off the engine. There are two types: Plus, coated radiator fins trap the symmetrical type, which has dirt which can diminish two identical filter sets and the cooling capability. main-auxiliary type, which has a main filter set and a smaller capacity Water Separation auxiliary filter set. A special valve Water in the diesel fuel is absolutely connects the two sets of filters in unwanted as it will cause damage to each type. The valve routes the fuel the engine and its components. Water to be filtered through either or both appears in the fuel because of con- sets of filters. densation, handling and environmental conditions. Environmental conditions Both filter sets can be used relate to the humidity of some simultaneously to extend running climates. Water in the fuel will be time in an emergency. more prevalent in humid climates. Duplex filters for fuel and Water can impact the fuel system lubricating oil allow extended in the following ways. operation without interruption.  If water appears in the injection  The main and auxiliary filter system, the fuel will not be able systems allow changing either to lubricate as it is supposed to the main or auxiliary filter and it will lead to early wear. elements with the engine  Water together with diesel fuel running under load. will form microbiological growth which will build up sludge. Sludge will cause wear of the filter system and influence the injection performance.

 Iron will oxidize when in  A centrifuge system can be contact with water and can used, particularly if the fuel infiltrate the fuel. The iron quality consistently falls oxide will cause injector wear. below the defined limits Engines using high injection discussed in this guide. pressure fuel pumps must be Centrifuges protected from water and sediment The centrifuge represents the most in the fuel. It is extremely important expensive and complex method of to maintain water and sediment water separation, but it is the most levels at or below 0.1%. effective. It is used extensively in Note: Water and sediment collecting marine, offshore and power in fuel tanks may give the appear- generation applications where a ance that poor quality fuel was continuous power supply is essential, delivered to the site. and the continuous supply of clean Several methods can be used to fuel cannot be left to chance. A remove excess water and sediment typical distillate fuel centrifuge from the fuel system: schematic is shown in Figure 9.  A water and sediment A centrifuge manufacturer should separator can be installed in be consulted to determine the proper the supply line ahead of the centrifuge type, size and flow transfer pump. The separator requirements for a specific must be sized to the handle application. the fuel being consumed by While Figure 9 shows a single the engine as well as fuel centrifuge schematic, many being returned to the tank. applications will require the use of  Coalescing filter systems work two (2) centrifuges, with one of the effectively to remove sediment centrifuges acting as a standby. and water. If the level in the The required flow rate of a day tank is not maintained at a centrifuge can be approximated as consistent level, install them follows: between the main tank and the P x b x 24 x 1.15 day tank. If proper day tank Q = levels are maintained, a smaller R x t system can be used between the main tank and the day tank Where: to clean only the fuel being burned. These filters can plug Q= Flow required, L/hr and careful attention must be P= Total Engine Output, kW given to fuel pressure levels at b= Fuel Consumption, g/kW-hr the injectors to guard against misfiring. R= Density of fuel, kg/m3 T= Daily separating time in automatic operation: 23 hr

Or: T= Daily separating time in f x be x 24 x 1.15 automatic operation: 23 hr Q = R x t Note the following considerations for configuring a centrifuge.

 The centrifuge manufacturer Where: should assist in the final Q= Flow required, gal/hr centrifuge selection. P= Total engine output, bhp  The centrifuge flow has been Be= Specific fuel consumption, increased by 15% as a safety lb/bhp-hr factor for operational tolerances. R= Density of fuel, lb/gal Typical Distillate Fuel Centrifuge System

Figure 9

Centrifuge seal water and control following pump characteristics are air requirements must be specified provided for guidance: by the centrifuge manufacturer.  Operating pressure - to suit Sample Points conditions of piping system The centrifuge operating efficiency  Operating fluid temperature - is checked by drawing samples from 38°C (100°F) both sides of the centrifuge.  Viscosity for sizing pump motor - 500 cSt Suction Strainer Install a simplex strainer ahead of Centrifuge Fuel Heater the centrifuge supply pump and use The heater is sized using the pump a stainless steel basket with capacity and the temperature rise perforations sized nominally at required between the settling tank 0.8 mm (0.03125 in) to protect the and the final centrifuge. The heater pump. The strainer body is normally should be thermostatically controlled manufactured from cast iron or and set to maintain fuel temperature bronze. to the centrifuge within ± 2°C (± 4°F). The maximum preheating Centrifuge Supply Pump temperature for distillate fuel is 40° Mount an electric motor driven to 50°C (104° to 122°F). supply pump separately from the centrifuge and size it appropriately for the centrifuge flow. The

Miscellaneous Fuel System Considerations

Fuel Temperature operating below the fuel stop limit, the governor will add fuel as The fuel temperature supplied to required to maintain the required the engine can affect unit injector engine speed and power. life and maximum power capability. Reduced lubrication capability due to Fuel Coolers high temperature/low viscosity fuel As mentioned earlier in the Basic may result in component scuffing. Fuel System description, Cat diesel The minimum allowable viscosity at engine fuel delivery systems are the injectors is 1.4 cSt. A maximum designed to deliver more fuel to the fuel temperature limit of 66°C engine than is required for (150°F) to the unit injectors, combustion, with the excess being regardless of fuel viscosity, prevents returned to the fuel tanks. This coking or gumming of the injectors. excess fuel, on many engines, is The maximum fuel viscosity to the used for cooling and lubricating of unit injectors of 20 cSt prevents the pumps and injection systems overpressure damage to the and in doing so picks up engine heat injectors. and can raise the temperature of the Maximum fuel temperature limits fuel in the tanks. to the low-pressure fuel transfer As previously specified, engine pump for Common Rail Fuel systems power will be reduced if the fuel vary with engine model. Values are temperature exceeds the maximum listed below in Table 4. limit because of the expansion of the fuel (low viscosity). With very low viscosity, the oil loses the capability Maximum Allowable Inlet Fuel to lubricate and damage to the Temperature to the Low Pressure Fuel Transfer Pump for Common Rail injection components will occur. Applications Proper considerations regarding fuel tank location and size will help C175 70°C (158°F) temperature control. If the tank is C7, C9, C15, C18 80°C (176°F) properly located and sized so the accumulated heat will not be Table 4 objectionable when temperature stabilizes, then nothing more needs The engines are power set at the to be done. If the stabilized fuel tank factory, and higher fuel temperature is high, the returning temperatures will reduce maximum fuel should be cooled. power capability. The fuel stop power reduction is 1% for each The following factors affect the need for fuel cooling equipment. 6°C (10°F) fuel supply temperature increase above the maximum fuel temperature limit. If the engine is

 Length of periods of A plate type heat exchanger may continuous operation; If the be used with titanium plates for operating periods are short, seawater cooling or stainless steel the amount of heat returned plates for fresh water cooling. to the fuel tanks will be Refer to Sea Water Systems in relatively small. Fuel coolers the Cooling Systems Application are not generally required for and Installation Guide for proper engines used in applications installation and maintenance requiring intermittent procedures of fuel cooler in sea operation. water applications.  Length of time between periods of operation; if the Fuel Heaters time between periods of Just as the ability to remove operation is long, the heat will excess heat from fuel is an have an opportunity to important design consideration in dissipate. some applications, so is the ability  Volume of the fuel tank; If the to add heat to fuel in applications volume of the fuel tank is involving cold environments. Diesel large (larger than 11 000 L fuel must not be too warm or too [3,000 gal]), it will accept a cool. Both cases will reduce life. great deal of heat before the With mid-distillate No. 1 or No. 2 temperature of the fuel diesel fuel, cold weather can cause leaving the tank increases wax crystals to form in the fuel significantly. systems, partially or completely Note: Day tank sizing is critical to blocking fuel flow. The addition of maintain the desired fuel supply a small amount of heat to the fuel temperature. Fuel coolers may be before it flows through the filter(s) required. For a more detailed can prevent wax problems. The fuel discussion of required fuel tank will flow through pumps and lines volume, see the Day Tank Sizing but not through filters at (When Serving as a Heat Sink) temperature below the cloud point section in Appendix 1. (where a cloud or haze appears in  Ability of the fuel tanks to the fuel). dissipate heat. In marine At temperatures below the pour applications for instance, fuel point (the lowest temperature that in contact with the shell fuel will flow or pour), fuel will not plating, where at least 10% of flow in lines or pumps. The use of the inside surface area of the fuel with a pour point above the tank is shell plating, the heat minimum expected ambient will be easily dissipated and temperature is not recommended. the stored fuel temperature Fuel heaters will often solve cloud will remain within a few point problems but not pour point degrees of the ambient water temperature.

©2013 Caterpillar Page 30 All rights reserved. Diesel Fuels & Diesel Fuel Systems Application and Installation Guide problems unless applied to the entire Maintenance responsibility of this fuel storage volume. type of heater must be clearly Consider the following suggestions defined. when applying fuel heaters to Cat  Fuel heaters offered by engines. Caterpillar use engine coolant  Fuel heaters should be used to heat the fuel and prevent when the ambient the development of solid wax temperature is below the fuel particles. cloud point. Many types of  When any fuel heater is used heaters can be used; and ambient temperatures are however, the fuel should be below approximately 0°C heated before the first filter in (32°F), the engine should be the fuel system. Fuel heaters started and run at low idle should not be used when the until the engine temperature ambient temperature exceeds rises slightly. This allows heat 15°C (60°F). Under no transfer to the fuel before condition should the maximum high fuel flow rates at high fuel temperature at the outlet power output are experienced of the fuel heater exceed the by the system. This will limit specified on the previous reduce the possibility of wax page. plugging the fuel filter shortly  Heaters used should be after a cold start. capable of handling the Partial Load Operation maximum fuel flow of the Extended operation at low idle or engine. The restriction created at reduced load may cause increased should not exceed published oil consumption and carbon buildup levels of the engine (published in the cylinders. Carbon buildup values for fuel flow and results in a loss of power and/or allowable restriction can be poor performance. When possible, found in the TMI). apply a full load at least on an hourly  Coolant may be taken from basis. This will burn excess carbon taps on the engine when from the cylinders. using the engine as a heat source. Care must be taken to Burning Used Crankcase Oil assure that coolant shunting With legislation and ecological to one system does not pressures, it is becoming adversely affect another increasingly difficult to dispose of system, and that both have used oil. The burning of used adequate flow. crankcase oil in 3600/C280 engines CAUTION: Failed water sourced fuel is not recommended due to the heaters can introduce excessive detrimental effects on exhaust water into the engine fuel system emissions. However, if ancillary and cause injector failure. methods of reducing exhaust

©2013 Caterpillar All rights reserved. Page 31 Application and Installation Guide Diesel Fuels & Diesel Fuel Systems emissions to acceptable limits are  Adequate mixing is essential. used, or if emissions are not a Lube oil and fuel oil, once mixed, problem, burning crankcase oil in will combine and not separate. 3600/C280 engines is possible with Mix used filtered crankcase oil the following guidelines. with an equal amount of fuel,  It is necessary to collect, then add the 50-50 blend to the store, and dispose of used supply tank before new fuel is crankcase oil from engines added (maintaining the 5% used correctly. It is not acceptable oil-to-fuel ratio). This procedure to dump used crankcase oil should normally provide into the oceans, rivers, and sufficient mixing. Failure to harbors from vessels or achieve adequate mixing will offshore drilling and result in premature filter plugging production platform by slugs of undiluted oil. installations. It may be Note: Review SEBU6251for fuel necessary for engine specifications operators to consider burning  Filter or centrifuge used oil crankcase oil in their Cat before putting it in the fuel engines. This can be done, tanks to prevent premature providing the precautions fuel filter plugging, below are carefully followed: accelerated wear, or plugging  Only diesel engine crankcase of fuel system parts. Soot, oils can be mixed with the dirt, metal, and residue diesel engine fuel supply. The particles larger than 5 microns ratio of used oil to fuel must (0.000197 in.) should be not exceed 5%. Premature removed by this process. If filter plugging will occur at filtering or centrifuging is not higher ratios. Under no used before adding the oil to circumstances should gasoline the fuel, primary filters with engine crankcase oil, 5 microns (0.000197 in.) transmission oils, special capability must be located hydraulic oils not covered by between the fuel supply and Caterpillar recommendations, engine. These will require grease, cleaning solvents, frequent servicing. etc., be mixed with the diesel  Clean handling techniques fuel. Do not use crankcase of the used crankcase oils oils containing water or are essential to prevent antifreeze from engine coolant introducing contaminants from leaks or poor storage outside sources into the diesel practices. fuel supply. Care must be taken in collecting, storing and transporting the used crankcase oil to the diesel fuel tanks. Diesel fuel day tank

sight glasses may become oil is centrifuged and directed to the blackened in time due to the clean waste oil tank. carbon content in the Centrifuge No. 2 crankcase oil. Ash content of Distillate fuel/oil mixture daytank the lube oil added to the fuel is continually centrifuged. may also cause accumulation of turbocharger and valve Metering Pump deposits more rapidly than Adds up to 5% clean waste oil normal. to the distillate fuel (from the main supply tank) when the daytank low Continuous Blending level switch calls for more fuel. If the installation warrants, used lubricating oil can be blended and Static Mixer used in the engine in a continuous Runs when the metering pump is manner. The normal method uses a on to insure a proper homogeneous centrifuge module similar to Figure mixture of the fuel and clean waste 9. The following information oil. describes this system. The centrifuge module is Centrifuge No. 1 electronically controlled and includes Engine crankcase oil is the components within the dotted continuously centrifuged except line as shown in Figure 10. Size the when the clean waste oil tank is system for appropriate fuel delivery. low, at which time the dirty waste

Figure 10

Fuel Conservation Practices Fuel costs typically represent the  Do not increase fuel settings single highest operating cost to obtain more power. associated with any diesel engine  Make sure all air hoses and application. This has promoted connections do not leak. various fuel conservation practices Leaks keep the compressor that can usually be applied to all working unnecessarily. applications.  Make sure the turbocharger  Avoid fuel spillage. Do not is turning freely so that proper overfill the fuel tank. Fuel air-fuel ratio is maintained. expands when warm and may A clean burning exhaust overflow, especially when should indicate these items tank is not designed correctly. are functioning correctly.  Operate the engine with a  Operate the engine with good electrical system. One a thermostat all year; cold bad cell in a battery will engines consume more fuel overwork the alternator, and wear out more quickly. consuming more engine  Keep air cleaners clean. Use horsepower and fuel. A poor an air cleaner restriction electrical system can also lead indicator to avoid guessing to hard starting, which at air cleaner condition. encourages excessive idling.  Size the engine or generator set to the job. Engines operate more efficiently at relatively high load factors.

Appendix 1 surrounding environment due to the Day Tank Sizing (When Day temperature difference between the Tank Serves as a Heat Sink) fuel mix temperature and the ambient temperature. This The fuel supply temperature must convective heat transfer then be within specified limits for determines the resultant tank optimum injector life and maximum temperature. The fifth step evaluates power capability. the impact of the final fuel supply Fuel systems without fuel coolers temperature on the engine’s rely on the day tank to dissipate the maximum power capability. heat of fuel returning from the The included example calculations engine. Day tank temperatures are should only be used to provide affected by the following conditions. general guidance. If the day tank  Day tank wetted surface area size is marginal, use a fuel cooler. (including tank bottom) To simplify the following  Engine(s) fuel consumption calculations, it is assumed the day rate tank walls are surrounded by free  Day tank replenishing level moving air. If the tank walls are  Storage tank fuel temperature contiguous to the shell plating, heat  Ambient temperature transfer from the day tank will be  Spaces contiguous to the day enhanced. Conversely, if the day tank (void tanks, cofferdams, tank is bounded by void spaces and vessel shell plating, etc.) cofferdams, heat rejection from the  Return fuel temperature day tank will be retarded. Typically, Tank temperature calculation are most day tanks are located with performed in five [5] steps. The first various combinations of the determines the fuel mass in the tank preceding boundary elements. The at each time interval. The second individual performing the evaluation step is based on a fuel mix must be familiar with the installation temperature resulting from the as well as the fundamental engine driven transfer pump flow engineering concepts of the formulas rate to the engine and the return used in the calculations. flow rate to the day tank. The third step determines the day tank fuel Day Tank Calculations height for each incremental time The following information is element. Typically, the calculations required to perform the calculations: will be based upon a 30-60 minute  Engine model iterative time function. The end  Engine developed power point for the calculation is assumed (MCR or CSR) to be when the day tank is refilled.  Engine speed The fourth step approximates the  Brake specific fuel heat transfer from the tank to the consumption (bsfc)

 Initial day tank fuel Assume that the day tank will be temperature replenished from the fuel storage  Storage tank fuel temperature tanks when the day tank level falls (Make-up) to approximately 50-55% of normal  Ambient air temperature operating capacity.  Day tank length, width, and Some of the data above must be height converted to other units prior to  Typical full day tank fuel beginning calculations. The following height (assume 95% of tank formulas can be used: capacity) 1. Engine Driven Transfer Pump  Engine fuel transfer pump Mass Flow Rate = Mxfer (lb/min) flow rate (see TMI) Assume: #2 DO with an API  Fuel heat rejection from the gravity of 35 (7.1 lb/gal) engine (see TMI) Mxfer = qxfer x 7.1 lb/gal =  Incremental time element 19.0 gpm x 7.1 lb/gal = Day Tank Thermal Capacity 134.9 lb/min Calculation 2. Engine burn rate under full load Example: conditions:  Application: Single main a. Burn rate (gpm) engine  Engine Model: 3612 bsfc x bhp x 1 Hr. =  Rated Power: 4640 bhp (CSR) Fuel density x 60 min.  Rated Speed: 900 rpm  bsfc: 0.326 lb/bhp-hr 0.326 lb/bhp-hr x 4640 bhp x 1 hr.  Initial Day Tank Fuel = 7.1 lb/gal. x 60 min. Temperature = 85°F

 Storage Tank Temperature = 85°F = 3.55 gpm  Ambient Air Temperature = 95°F  Day Tank Dimensions: b. Fuel mass flow burn rate o Length (L) = 12 ft. = MBR (lb/min) o Width (W) = 8 ft. o Height (H) = 8.42 ft. = 3.55 gpm x 7.1 lb/gal  Fuel Height (@ 95% of total Capacity) (H) = 8 ft. = 25.21 lb/min  Engine Fuel Oil Transfer Pump Flow Rate: qxfer = 19.0 gpm  Heat rejection from engine to fuel oil: Q = 1252 Btu/min  Incremental time element: t = 60 min.

Step 1 3. Engine fuel return rate under full Calculate the fuel mass in the day load conditions: tank at specific time intervals: a. Fuel return flow rate Day Tank Fuel Quantity = MDT - = qrtn (gal/min) (MBR x t) Where: = Supply rate - burn rate MDT = Day tank contents at a specific time step (lbs) = 19.0 gpm - 3.55 gpm MBR = Engine fuel consumption = 15.45 gpm (lb/min) t = Incremental time step (min) b. Fuel return mass flow rate Assume the day tank is replenished = Mrtn (lb/min) at 55% of initial quantity of fuel. Prepare a table of volumes as shown = 15.45 gpm x 7.1 lb/gal below for this example. Refer to Table 5. = 109.70 lb/min

Incremental Tank Fuel Capacity 4. ∆TENG of fuel = (Tsupply - Trtn) Time (Min) Quantity (lb) (%) 0 40258.6 100.0 Q 60 38746.0 96.2 ∆TENG = Mrtn x Cp 120 37233.4 92.5 180 35720.8 88.7 240 34208.2 85.0 1252 Btu/min = 300 32695.6 81.2 (109.70 lb/min x 360 31183.0 77.5 0.5 Btu/lb-°F) 420 29670.4 73.7 480 28157.8 69.9 = 22.83°F 540 26645.2 66.2 600 25132.6 62.4

660 23620.0 58.7 5. 95% Capacity of Diesel Oil Day 720 22107.4 54.9 Tank, (lb) Refill 40258.6 100.0 Weight density (p) for #2 diesel oil = 52.42 lb/ft3 Table 5

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 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: Values for the example calculation:

MDT = Day tank contents at a MDT(t -1) = Day tank contents from specific time step (lb) previous time step (lb)

Mxfer = Engine transfer pump Mxfer = 134.9 lb/min mass flow rate (lb/min) T = 60 min.

T = Incremental time step TDT(t -1) =Initial day tank (min) temperature is used for TDT(t -1) =Day tank temperature for first iteration, 85°F

previous time step or MRTN = 109.70 lb/min starting temperature (°F) ∆TENG = 22.83°F MRTN =Engine return mass flow MBR = 25.21 lb/min rate (lb/min) ∆T ENG= Fuel temperature rise across the engine (°F)

MBR = Engine fuel consumption (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 for Step 3 each increment (t). Calculate the height of fuel Prepare a summary table as shown contained in the day tank at t = in Table 6 for each increment (t). incremental time step. Prepare a summary table for each time

increment (t) as shown in Table 7. Incremental Mix Time (Min) Temperature (°F) MDT 0 85.0 H= 60 88.9 p x L x W

120 92.9 180 97.1 Where: 240 101.5 H = Height of fuel in the tank

300 106.1 MDT = Fuel contained in the day 360 110.9 tank at each incremental time 420 116.0 step 480 121.3 p = Weight density of #2 DO 540 126.9 (52.42 lb/ft3) 600 132.9 L = Length of day tank (12 ft) 660 139.3 W = Width of day tank (8 ft) 720 146.1

Refill Incremental Time Height (ft) Table 6 (min) 0 8.0 60 7.7 120 7.4 180 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 7

Step 4 Calculate the heat transferred between the fuel in the day tank and the atmosphere, the ∆T of the fuel in the day tank due to the heat transfer, and the 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 - x t [ 2 ]

Where: b. Temperature change in the day

QTK =Heat transfer to/from tank resulting from heat to/from atmosphere (Btu) day tank: This considers 6mm (0.25 QTK ∆ TDT = in.) steel plate forming the MDT x Cp tank boundaries, and the film coefficient for air and Where: oil. The air side film ∆TDT = Temperature change of coefficient is predominant fuel in the day tank (°F) when compared to the oil side film. The tank thickness QTK = Heat transfer to/from has a negligible effect. atmosphere (Btu) U = Coefficient of heat MDT = Mass of fuel in day tank transfer, (0.0424 Btu/min (lb) 2 •ft •°F) CP = Specific heat of #2 MDO L = Day tank length (ft) = 0.5 Btu/lb •°F W = Day tank width (ft)

TAMB = Ambient temperature (°F) c. Day tank temperature resulting from heat transfer to/from day TMIX = Mix temperature of return tank: fuel and fuel in tank (°F) TDT = TMIX + ∆TDT TDT = Day tank temperature

resulting from heat transfer to/from day tank (°F) Where: T = Incremental time step TDT = Day tank temperature (min) (°F) H = Fuel height for specific TMIX = Mix temperature of return time step (ft) fuel and tank fuel (°F)

∆TDT = Temperature change of day tank (°F)

These three calculations are ∆TDT is then used to determine TTK. interdependent in nature. First, QTK is This process is then repeated for determined for the first incremental each incremental time step. time step. The resulting value for QTK is then used to compute the ∆ TDT. Example a.: (TMIX + TDT) QTK = U x [ (H x (2L + 2W) + (L x W) ] x TAMB - x t [ 2 ]

(88.9 + 85) QTK =0.0424 x [7.7 (40) + 96] x 95 - x 60 [ 2 ]

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 incremental time steps.

Prepare a summary table for each time increment (t) as shown in Table 8. Incremental Time Heat Rejection to/from Temperature Chg. in Day Tank Temperature (min) Day Tank (Btu) Day Tank (°F) (°F) 0 - - 85.0 60 8283.6 0.43 89.3 120 4069.7 0.22 93.2 180 -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 -2.98 143.1 Refill - - 116.9 Table 8

The last part in Step 4 determines the day tank temperature 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 the Corrected Incremental Day Tank Engine Power maximum power capability of the Time (min) Temp. (°F) engine at the resultant day tank (bhp) temperature for each time interval. 0 85.0 - A summary table for each increment 60 89.3 4625 (t) is also prepared and shown in 120 93.2 4607 Table 9: 180 97.1 4588 240 101.3 4569 Note: The engines are power set at 300 105.6 4549 the factory with 30 ±3°C (86 360 110.2 4528 ±5°F) fuel to the engine transfer 420 114.9 4506 pump. Higher fuel temperatures 480 120.0 4482 reduce maximum power capability. 540 125.2 4458 The fuel stop power reduction is 1% 600 130.8 4432 for each 5.6°C (10° F) fuel supply 660 136.8 4405 temperature increase above 30°C. 720 143.1 4375 If the engine is operating below the Refill 116.9 4497 fuel stop limit, the governor will add fuel as required to maintain the Table 9 required engine speed and power.

Conclusion (TDT - Tref ) 1 The previous calculations indicate Pcorr = Prated x 1 - X [ 10°F 100 ] day tank fuel temperatures can have an effect on the maximum power Where: capability of the engine. The example was based upon a fixed pitch propeller Pcorr = Corrected Engine Power, bhp application. Typically, a fixed pitch propeller is selected and sized to Prated = Rated bhp absorb 85-90% of the engine's name Tref = 86° (Power setting) plate rating. In this example, this

TDT = Actual day tank fuel would equate to 3950-4175 bhp. The temperature, °F lowest calculated corrected power was determined to be 4375 bhp. This Example: would leave a 5-10% power margin For t = 60, the corrected power of and vessel performance would not be the engine is: affected.

While vessel performance may not 1 - (89.3°F - 86°F) 1 be affected in this example, the max- Pcorr = 4640 bhp x [ X ] 10°F 100 imum fuel temperature of 143.1°F

will put the fuel viscosity near or Pcorr = 4625 bhp below the minimum allowable viscosity of 1.4 cSt at the injectors

©2013 Caterpillar All rights reserved. Page 43 Application and Installation Guide Diesel Fuels & Diesel Fuel Systems depending on the type of distillate fuel Aside from the impact on engine being used. In addition, the temp- performance, maximum fuel tank erature of the fuel in the tank after temperatures are also established refill is now 116.9°F instead of 85°F by various marine classification as used at the beginning of the societies and regulatory bodies. iteration. Therefore, continued Their interest is based upon the operation at full load on this fuel tank increased risks of fire that results would cause the fuel temperature to from elevated fuel temperatures. rise even higher than the maximum temperature shown in this iteration. To protect the fuel injectors a fuel cooler should be used in this application, despite the fact that available engine power is still acceptable. 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)

Density SG = 998 kg/m3

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

1 lbm/ft3 1 ft3 Density (lbm/gal)= SG x 998 kg/m3 x x 16.02 kg/m3 7.48 gal

Mass Flow Rate 1m3 Flow Rate (L/min) M (kg/sec) = Density (kg/m3) x x 1000 L 60 (sec/min)

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

Specific Heat (cp) Table 10 shows typical specific heat values for two different API gravity fuels in Btu/lbm-°F: 38°C 60°C 82°C 93°C 115°C API Gravity (100°F) (140°F) (180°F) (200°F) (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 10

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 components and to permit Crude Oil Fuel satisfactory starting capability. Note: Crude oils are not suitable for The same diesel power ratings may use as fuel in all engine applications. not always apply for Cat engines The suitability of these fuels for use burning crude oil. Reasonable engine is determined on a case-by-case service life can be achieved when basis. A complete fuel analysis is proper procedures are followed. required. However, the greater risks involved NOTICE: Use of permissible crude make it good practice to include oil fuels can result in higher slightly higher than normal maintenance costs and in reduced maintenance costs when figuring the engine service life. overall economics to be gained. NOTICE: Caterpillar does not A fuel analysis should be recommend using any of the heavier performed. Include a distillation fractions such as residuals or curve. Operation at light load is not bottoms in engines that are recommended. On occasion, configured to use distillate diesel operation at 50% load has fuel. Failure to follow this reportedly caused smoking. recommendation will result in severe Engines for crude oil fuel operation wear of components and engine should be equipped with higher failure. temperature thermostats, bypass Residual fuels or blended fuels centrifugal oil filter, and fuel injector with residuals are unsuitable pushrod keepers. because they have a high viscosity Pretreatment of Crude Oils range, low ignition quality and high 1. The crude may contain excessive vanadium and sodium contents that amounts of sediment and water shorten engine life. Such fuels may that will require removal before cause high wear rates in the fuel they get to the engine. This can system, on the piston rings, cylinder usually be accomplished with a liners, and exhaust valves. Also, settling tank, Figure 11, a filter problems and deposits in the centrifuge or special filtering piston ring belt may be evidenced. equipment or a combination of Special crude oil fuel pretreatment these methods. The crude may equipment may be required and is also contain solid particles of available from suppliers of fuel wax at ambient temperature that treatment equipment. Also, it may would plug the filters rapidly. It is be essential to start and stop the impractical to try to remove the engine on a better quality, ASTM wax, but the crude can be heated No. 2-D type fuel to prevent sufficiently to dissolve it. The plugging and sticking fuel system amount of heat needed will vary from one crude to another and

each situation requires an exceed 30% of the total crude. assessment. Jacket-water heated The kerosene, distillate and gas fuel filters, available from fuel oil fractions combined should equipment suppliers, are often make up at least 30% of the suitable for heating the crude. total because they have high If this is not appropriate for you cetane numbers. application, an external heating 4. Another problem created by highly system will be necessary. volatile crude oils (low initial 2. The crude oil must not have too boiling points) is vapor locking of high a viscosity. For maximum life the fuel system. This situation can and minimum maintenance of the be handled by an “air eliminator.” fuel pumping and injection This, in some cases, can be an systems, the viscosity of the crude ordinary float-type steam trap oil in these systems should be inverted, but it should be made of within 1.4 to 20 cSt at 104°F corrosion-resistant materials. It (40°C). If the crude’s natural should be located after the viscosity is higher than this, it may auxiliary filters. If the engine is be heated or diluted to reduce it. stopped occasionally and allowed The degree of heating required will to cool, coagulation may build up vary from one crude oil to another in this vapor trap and cause it to and will have to be established in be inoperative. each case. Another method of 5. The proper oil change reducing viscosity is to blend the recommendation must be made original crude with a sufficient in each case. Many crude oils amount of lighter distillate contain large amounts of material material. Again, the blending that accelerate lube oil proportions would have to be deterioration. For this reason, determined for each crude oil. the standard change period with 3. The crude must have a cetane recommended oils should be number of at least 40. This reduced by one-half. From this brings its distillation character- point, the length of change period istics into the picture. The cetane with crude is determined by sulfur number should be determined by content the same as with distillate actual engine test because fuels. With 0.4-1.0% sulfur, the calculated numbers of crude oils change period should again be are unreliable. The cetane number reduced by one-half. When sulfur of a crude oil is a function of its content exceeds 1.0%, still further composition. Crude is generally reduction is recommended. In subdivided into fractions by many cases, it may be desirable to boiling temperatures. The install a larger capacity lube oil combination of the gasoline and system to avoid short oil changes. naphtha fractions, which have The use of Cat S•O•SSM, is low cetane numbers, should not strongly recommended.

Crude Oil Maintenance inside the settling tank building Intervals should be maintained above 70°F Engine inspection intervals should (21°C), and the tanks must be be reduced by 50% when using vented outside the building. crude oil as fuel, and maintenance A two-day supply of diesel fuel routines should be modified based should be maintained for emergency on the results of these increased use. This supply can also be used to inspections. start and stop engine when the crude oil fuel is highly viscous or Crude Oil Settling Tanks heavy with paraffins. A great deal of sludge can be removed from crude oil by proper settling. A recommended settling system consists of two cone- bottomed tanks, Figure 11, each holding a little more than four days usable supply of fuel. Sludge in the bottom third is discarded before refilling. The tanks must be housed in a heated building, and each fitted with heating coils. Immediately after filling, hot water is circulated through the heating coil until the tank is heated to 100°F Figure 11 (38°C). The heat is then shut off and the fuel allowed to settle undisturbed for four days. During this time, fuel is being used from a second tank. Temperature

Crude Oil Specification Specification and ASTM Test Method Requirements Cetane number (1) (ASTM D613) Minimum 40 (DI Engines) Water and sediment % volume (ASTM Maximum 0.5% D1796) Pour point (ASTM D97) Minimum 10°F (6°C) below ambient temperature Not higher than lowest expected ambient Cloud point (ASTM D97) Maximum temperature 3% - See pages 131 & 132 to adjust oil TBN for Sulfur (ASTM D3605 or D1552) Maximum sulfur content that is above 1% Minimum 1.4 cSt (2) Kinematic Viscosity 20 cSt (as delivered to rotary fuel injection pumps) Maximum 20 cSt (as delivered to other fuel injection pumps) Maximum 45 API gravity (ASTM D287) Minimum 30 Maximum 0.8017 Specific gravity (via Standards tables) (3) Minimum 0.8762 Gasoline and naphtha fraction (fractions boiled off below 392°F Maximum 30% Kerosene(200°C)) and distillate fraction (fractions boiled off Minimum 30% B 392°F (200°C) d ki Carbon residue (on 10% bottoms) Maximum 3.5% (ASTM D524)

Distillation - 10% Maximum 540°F (282°C) - 90% Maximum 716°F (380°C) - cracking Minimum 60% - residue (ASTM D86) Maximum 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 kL) 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 are unreliable. 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 of comparison, fuels should also meet the minimum and maximum viscosity requirements at 40°C (104°F) that are stated 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 injection pump. Fuels with a high viscosity might require fuel heaters in order to bring down the viscosity to either 4.5 cSt or less 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 of 15.56°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 Cat dealer for the most up-to-date fluids recommendations.

Reference Material The following information is provided as an additional reference to subjects discussed in this manual. REHS4726 Special Instruction SEBD0717 Diesel Fuels and Your Engine SEBU6251 Cat Commercial Diesel Engine Fluids Recommendations SEBU7003 3600/C280 Diesel Engine Fluids Recommendations for Lubricants, Fuels, and Coolants REHS0104 Guidelines for 3600/C280 Heavy Fuel Oil (HFO) Engines SENR9620 Improving Component Durability: Fuel Systems WECAP Web Engineering Cataloging and Procuring website

CAT, CATERPILLAR, their respective logos, “Caterpillar Yellow,” the “Power Edge” trade dress as well as corporate and product identity used herein, are trademarks of Caterpillar and may not be used without permission.