The document discusses the key properties and standards for diesel fuel. It covers: 1) Diesel fuel is made from petroleum and refined through processes like hydro-treating to remove sulfur. Its main components include paraffins, isoparaffins, napthenes and aromatics. 2) Diesel fuel standards (ASTM D975) specify properties like cetane number, viscosity, sulfur content, distillation range and others that affect engine performance and emissions. 3) Properties like cetane number, density, cloud point and lubricity are important for combustion quality and low-temperature operability. Additives can be used to modify properties.

1. Understanding Today’s Diesel Fuel National Biodiesel Board Technician Outreach Program

2. Objectives Understand the new face of diesel fuels What are today’s diesel fuel quality standards How are these standards set? How do these fuel standards affect the diesel engine operation? - performance - emissions - fuel economy

3. Emissions Regulations in the driver’s seat The Clean Air Act of 1970 gave EPA broad authority to regulate motor vehicle pollution, and the Agency's emission control policies have become progressively more stringent since the early 1970's.

4. Diesel Emission Reductions

5. What is Diesel Fuel Various Petroleum Components: Paraffins Isoparaffins Napthenes Olefins Aromatic Hydrocarbons

6. How is diesel made? Petroleum coke is heated up to separate the complex mixture of hydrocarbons into usable products like diesel. Each petroleum derived product is distinguished by its boiling point. Diesel fuel undergoes a hydro-treating process to remove sulfur.

8. Typical Refinery Products From: Schmidt, G.K. and Forster, E.J., “Modern Refining for Today’s Fuels and Lubricants,” SAE Paper 861176, 1986. Solid Petroleum Coke 1000 + 540 + Asphalt 650 - 1200 340 - 650 Residual Oil 650 - 1000 340 - 540 Lube Oils 350 - 650 180 - 340 #2 Diesel, Furnace Oil 340 - 515 170 - 270 Kerosene, Jet Fuel, #1 Diesel 80 - 400 30 - 200 Gasoline -40 - 31 -40 - 0 LPG Product Boiling Range Deg. F Boiling Range Deg. C

9. Grades of Diesel Fuel 1-D ( S15) 1-D ( S500) 1-D (S5000) 2-D ( S15) 2-D ( S500) 2-D (S5000) 4-D S15, S500, & S5000 relate to sulfur content Off-road versus On-road use Varied in density and viscosity

10. ASTM Specifications for Diesel Fuel - ASTM D 975

11. Diesel Fuel Specification ASTM D 975 Flashpoint Water and Sediment Distillation Kinematic Viscosity Ramsbottom Carbon Residue Ash Sulfur Copper Strip Corrosion Cetane Number Cetane Index Aromaticity Cloud Point

12. Cetane Number Measures the readiness of a fuel to auto-ignite. High cetane means the fuel will ignite quickly at the conditions in the engine (does not mean the fuel is highly flammable or explosive). Most fuels have cetane numbers between 40 and 60. ASTM D 975 requires a minimum cetane number of 40 Premium Diesel fuel typically has a cetane of 47 ASTM methods are ASTM D-613 (ISO 5165) and D-6890

13. Cetane Cetane engine shown above from petroleum testing facility Ignition Delay: the period that occurs between the start of fuel injection and the start of combustion; the higher the cetane number, the shorter the ignition delay and the better the quality of combustion.

14. Low Cetane Impact Poor Ignition Quality Long ignition delay Abnormal Combustion Possible High Combustion Pressure Increased Engine stress Excessive Engine Knock Smoke on Cold start

15. Cetane Index Cetane index is used as a substitute for the cetane number . The cetane index is calculated based on the fuel's density and boiling range. Two methods used ASTM D-976 or D-4737. Cetane improvers that may be added are not accounted for in the index

16. Boiling Point and Volatility Diesel fuel volatility needs vary for engine load, size, & speed Buses & trucks benefit from more volatile fuel ASTM D975 sets a min-max range Defines the upper and lower limits for 90% distilled point. No. 1 diesel: no lower limit, upper = 288 C No. 2 diesel: lower limit = 282 C, upper = 338 C. 282C - 338C

17. 90% Distillation Temperature Volatility or Boiling Point is controlled by the Distillation specifcaition or T90 Primarily used to separate diesel fuels into different grades. Limits the amount of wax allowed in No. 1 If distillation temperatures are too low, then the fuel may have difficulty meeting the flashpoint requirement. If distillation temperatures are too high, then there is an increased tendency of the fuel to deposit on the cylinder wall, where it can be swept down past the rings and into the lube oil.

18. Viscosity Low viscosity = power loss, component wear due to injector leaking or injection pump leak-down Low viscosity = poor lubrication ability High viscosity = Poor fuel dispersion, ie improper injector spray pattern High viscosity = high pump resistance and early pump failure Critical property for fuel injection system performance Measured with ASTM D 445. #1 diesel fuel = 1.3 – 2.4 mm 2 /s #2 diesel fuel = 1.9 – 4.1 mm 2 /s

19. Carbon Residue Measure of a diesel fuel’s tendency to form engine deposit Tests basically involve heating a sample of fuel to a temperature where the fuel will pyrolyze (decompose without oxygen), leaving a carbon-rich deposit (about 500 °C) Test is frequently done on the 10% residue of fuel distillation. Limitation is 0.35 mass percent for No. 2 D Limitation is 0.15 mass percent for No. 1 D

20. Ramsbottom Carbon Residue There are many tests for carbon residue: Ramsbottom (D 524) Conradson (D 189) Micro Method (D 4530) Diesel fuel specification requires Ramsbottom Carbon reside can vary with refinery processes

21. Sulfur Content Sulfur can impact engine wear and deposits due varying levels Sulfur in diesel will now harm new emission control devices of 2007 & newer vehicles Sulfur burns to sulfur dioxide and sulfur trioxide, which can combine with water to form sulfuric acid. Small droplets of sulfuric acid and other sulfates contribute to particulate emissions. Sulfur is limited by the EPA for both on & off road diesel fuels: In 1993: Reduced from 5000 ppm to 500 ppm In 2006: Reduced from 500 ppm to 15 ppm

22. Sulfur Testing ASTM D 129 was traditional method but did not have sensitivity for new low sulfur fuels. (Bomb method) ASTM D 2622, X-Ray Spectrometry, is more sensitive but may not be adequate for 15 ppm diesel fuels.

23. Flashpoint Measures the temperature at which the vapors above the liquid can be ignited. Primarily used to determine whether a liquid is flammable or combustible Flashpoint is important for safety and hazard rating Both DOT and OSHA say that any liquid with a flash point below 100F is flammable ASTM D 93 is most common test for diesel fuels. Can also be used to identify contamination from other fuels. No. 1 = 38 °C, No. 2 = 52°C

24. Flashpoint

25. Low temperature Operation Cloud point is the measurement of low temperate operation It dictates the temperature at which fuel first starts to crystallize and wax up when cooled Cloud point can predicate fuel filter clogging in some fuel delivery systems, but not all Other Low temp tests include: CFPP: Cold Filter Plugging Point LTFT: Low Temperature Flow Test Pour Point and Cold Soak Filtration Test

26. Cloud Point No specific value is given in ASTM D975. Requirements vary depending on geography. 10 th percentile temperature map corresponds to the minimum temperature that would be reached no more than 3 days out of 30 for the month. ASTM D 975 contains similar maps for other low temperature months in the United States.

27. Ash Abrasive Solids Soluble metallic soaps Originates from inorganic fuel components D 975 requires ash to be < 0.01%, by mass Injector & Fuel pump wear Piston and Ring wear Solids = engine deposits

28. Copper Strip Corrosion Used to predict problems with copper, brass, or bronze components in a fuel system A measure of corrosiveness Polished copper strip is placed in fuel for 3 hours at 50 °C, then cleaned with a solvent and inspected for tarnish or corrosion. The strip is given a score between 1 and 4 with subdivisions indicated by letters, i.e. 2c means moderate tarnish with lavender coloring. Diesel fuel is allowed to be No. 3, which allows all tarnish but no actual corrosion.

29. Water and Sediment Measures free, not emulsified, water and insoluble particles. Uses a centrifuge and cone-shaped or pear-shaped bottles. Total volume of water and sediment must be < 0.05%.( 500 ppm) Contamination issue in supply line Engine impact: Filter plugging, fuel injection system wear, and corrosion, and opportunity for microbial growth

30. Lubricity Lubricity test methods are continually improving and being evaluated Most common tests available to test lubricity: SLBOCLE (scuffing load ball on cylinder lubricity evaluator) ASTM D 6078-99 HFRR (high frequency reciprocating rig) ASTM D 6079-99 D975 points to the HFRR test Limitation is 520 micron max of wear at 60C

31. SLBOCLE SLBOCLE “ Scuffing Load Ball-On Cylinder Lubricity Evaluator” Steel ball bearing on a steel rotating-ring Immersed in the test fluid Weight is applied until a “scuff” mark is seen on the rotating ring Tangential force recorded High Friction coefficient = scuffing 3100 grams without scuffing passes the SLBOCLE. (SWRI)

32. HFRR A steel ball Reciprocated (1mm) 200g load at 50 Hz for 75 minutes 2 mL of Fuel Adjust to 25 °C or 60 °C (77 °F or 140 °F 60°C preferred Ball contacts test disk (in fuel)

33. Specific Gravity & API Density

34. Density Specific gravity – ratio of the density of the fuel to the density of water. #1 diesel = 0.81 #2 diesel = 0.840 – 0.855 API gravity – common in petroleum industry. API = 141.5/SG – 131.5 Can be one indicator of fuel economy, power, deposits, wear, and exhaust smoke For example, a low API (or high density) has bore BTUs/gallon which could improve fuel economy

35. Energy Content Heating value of the fuel Not specified by ASTM Typically expressed as BTUs/gallon Engine Manufacturers Impact fuel ecomony No. 2 D 130,000 BTUs/gallon Gasoline 114,200 BTUs/gallon

36. Thermal & Oxidative Stability Chemical degradation occurs with contact with oxygen for long periods or at high temperatures. Oxidation of diesel fuel can form insolubles and peroxides Peroxides increase deposits and gumming on fuel pumps and injection systems Filter plugging will also occur ASTM D975 now specifies a stability parameter

37. Diesel Fuel Additives

38. Recent Changes in ASTM D975 Diesel Fuel specification Acid Number Allowance of up to 5 % biodiesel content Lubricity Stability

39. Resources for Diesel Fuel Properties ASTM International EPA, Environmental Protection Agency Changes in Diesel Fuel USDA Biodiesel education • Internal Combustion Engine Fundamentals, John B. Heywood, McGraw Hill, 1988 ISBN 0-07-100499-8 • Automotive Fuels Reference Book, Keith Owen, Trevor Coley SAE, 1995, ISBN 1-56091-589-7