Signicance of Test for Petroleum AST

Signicance of Tests for

Petroleum Products8th Edition

Salvatore J. Rand, Ph.D. Editor

Copyright by ASTM Int'l (all rights reserved); Mon Apr 11 11:51:23 EDT 2011 Downloaded/printed by Univ de los Andes Colombia pursuant to License Agreement. No further reproductions authorized.

Significance of Tests for Petroleum Products8th Edition

Salvatore J. Rand, EditorASTM Stock Number MNL1-8TH


ii

Library of Congress Cataloging-in-Publication Data Significance of tests for petroleum products. 8th ed. / [edited by] Salvatore J. Rand. p. cm. ISBN 978-0-8031-7001-8 1. PetroleumTesting. 2. Petroleum productsTesting. I. Rand, Salvatore J., 1933 TP691.M36 2009 665.50 38dc22

2010003804

Copyright 2010 ASTM International, West Conshohocken, PA. All rights reserved. This material may not be reproduced or copied, in whole or in part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of the publisher. Photocopy Rights Authorization to photocopy items for internal, personal, or educational classroom use of specific clients is granted by ASTM International provided that the appropriate fee is paid to ASTM International, 100 Barr Harbor Drive, PO Box C700. West Conshohocken, PA 19428-2959, Tel: 610-832-9634; online: http://www.astm.org/copyright/ ASTM International is not responsible, as a body, for the statements and opinions advanced in the publication. ASTM does not endorse any products represented in this publication. Printed in Newburyport, MA, May, 2010


iii

ForewordTHIS PUBLICATION, Significance of Tests for Petroleum Products: 8th Edition, was sponsored by ASTM committee D02 on Petroleum Products and Lubricants. The editor is Salvatore J. Rand, Consultant, North Fort Myers, Florida. This is the 8th edition of Manual 1 in the ASTM International manual series.


iv

DedicationTo Mary, Cathy, Jeanne, Joseph, and John


v

AcknowledgmentsThis manual was brought to fruition by the combined efforts of many individuals. I would like to convey my sincerest appreciation to all of them, particularly the publication staff of ASTM International, especially Kathy Dernoga and Monica Siperko, who have given us much behind-the-scenes guidance and assistance from the outset of this venture. I also wish to thank Christine Urso of the American Institute of Physics, who was responsible for this logistically challenging project of handling the 24 chapters and 37 authors involved in this publication. In addition, I wish to convey my accolades to the authors, who are all experts in their particular fields and who bring a broad spectrum of topics and interests to this manual. They have devoted considerable time, energy, and resources to support this endeavor. I am also grateful to the 46 experts who reviewed the various chapters, who through their perusal of the chapters and their suggestions permitted good manuscripts to be made better. Finally, I would like to extend my appreciation to the industrial and governmental employers of all those involved in this publication. They ultimately make it possible for us to produce manuals such as this for the benefit of those who use petroleum standards worldwide.



vii

ContentsChapter 1Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 by Salvatore J. Rand Chapter 2Automotive Spark-Ignition Engine Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 by Lewis M. Gibbs, Ben R. Bonazza, and Robert L. Furey Chapter 3Fuel Oxygenates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 by Marilyn J. Herman and Lewis M. Gibbs Chapter 4Fuels for Land and Marine Diesel Engines and for Nonaviation Gas Turbines . . . . . . . . . . . . . . . . . . . . 33 by Steven R. Westbrook and Richard T. LeCren Chapter 5Biodiesel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 by Steve Howell Chapter 6Burner, Heating, and Lighting Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 by C. J. Martin and Lindsey Hicks Chapter 7Aviation Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 by John Rhode Chapter 8Crude Oils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 by Harry N. Giles Chapter 9Properties of Petroleum Coke, Pitch, and Manufactured Carbon and Graphite . . . . . . . . . . . . . . . . . . 123 by C. O. Mills and F. A. Iannuzzi Chapter 10Sampling Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 by Peter W. Kosewicz, Del J. Major, and Dan Comstock Chapter 11Methods for Assessing Stability and Cleanliness of Liquid Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 by David R. Forester and Harry N. Giles Chapter 12Gaseous Fuels and Light Hydrocarbons [Methane through Butanes, Natural Gasoline, and Light Olefins] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 by Andy Pickard Chapter 13Petroleum Solvents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 by R. G. Montemayor Chapter 14White Mineral Oils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 by C. Monroe Copeland Chapter 15Lubricant Base Oils. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 by Jennifer D. Hall Chapter 16Lubricating Oils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 by Dave Wills Chapter 17Passenger Car Engine Oil and Performance Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 by Raj Shah and Theodore Selby Chapter 18Petroleum Oils for Rubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 by John M. Long and John H. Bachmann Chapter 19Lubricating Greases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 by Raj Shah Chapter 20Petroleum Waxes Including Petrolatums . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252 by Alan R. Case Chapter 21Methods for the Environmental Testing of Petroleum Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 by Mark L. Hinman Chapter 22Determination of Inorganic Species in Petroleum Products and Lubricants . . . . . . . . . . . . . . . . . . . . 283 by R. A. Kishore Nadkarni Chapter 23Standard Test Method Data Quality Assurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 299 by Alex T. C. Lau Chapter 24Synthetic Liquid Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304 by Lelani Collier, Carl Viljoen, Mirriam Ajam, Mazwi Ndlovu, Debby Yoell, Paul Gravett, and Nico EsterhuyseCopyright by ASTM .Int'l (all rights.reserved);.Mon.Apr 11. 11:51:23 EDT 2011 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Downloaded/printed by Univ de los Andes Colombia pursuant to License Agreement. No further reproductions authorized.


1IntroductionSalvatore J. Rand1TECHNOLOGY IS UNDERGOING ACCELERATING change. No longer do people have to wait months or even years for analytical methods to be submitted to ASTM International, tested, and voted for approval. The response of the various committees of ASTM International to new developments in the industrial and petroleum industries, and to unexpected occurrences in the field, is both swift and focused. It is because of this unprecedented and exponential increase in new testing methods that Manual 1 is being revised only 6 years after its prior publication. Committee D02 on Petroleum Products and Lubricants has assumed the responsibility of revising Manual on Significance of Tests for Petroleum Products (ASTM Manual Series: MNL 1), although other national and international standards organizations contribute significantly to the development of standard test methods for petroleum products. These organizations include the Energy Institute (EI), formerly known as the Institute of Petroleum in the United Kingdom, the Deutsches Institut fur Normung (DIN) in Germany, the Asso ciation Franaise de Normalisation (AFNOR) in France, the Japanese Industrial Standards (JIS) in Japan, the CEN (European Committee for Standardization), and the International Organization for Standardization (ISO). Selected test methods from these organizations have been cross-referenced where relevant with ASTM International standards in selected chapters in this publication. There are discussions presently in progress to harmonize many standard test methods so they are technically equivalent to one another. The chapters in this manual are not intended to be research papers or exhaustive treatises of a particular field. The purpose of the discussions herein is to answer two questions: What are the relevant tests that are done on various petroleum products and why do we perform these particular tests? All tests are designed to measure properties of a product such that the quality of that product may be described. I consider a workable definition of a quality product to be that which meets agreed-on specifications. It is not necessary that the quality of a product be judged by its high purity, although it may very well be, but merely that it meets specifications previously agreed on among buyers, sellers, regulators, transferors, etc. The various chapters in this publication discuss individual or classes of petroleum products and describe the standardized testing that must be done on those products to assure all parties involved that they are dealing with quality products. Since publication of the previous edition of the manual, not only has the number available but also the type of some petroleum products undergone dramatic changes. The result is that most products have had changes incorporated into

MNL1-EB/May 2010

their methods of test, and that these new procedures have been standardized and accepted into specifications as required. The generic petroleum products discussed in this eighth edition of Manual 1 are similar to those products described in the chapters of the previous edition. All chapters with one exception have been updated to reflect new specification and testing standards, where applicable. Chapter 21, Methods for the Environmental Testing of Petroleum Products, has been reprinted in its entirety from the previous edition because the test procedures and protocols have been essentially unchanged and the discussion of toxicity and biodegradation of petroleum products is relevant to todays products. In the discussion of some of the various petroleum products, selected sections of chapters have been retained from the seventh edition for the sake of completeness and to provide more complete background information. The authors of the chapters in the seventh edition have been credited in the footnotes to the appropriate chapters where necessary. This edition has been enlarged by the inclusion of three new chapters to more fully reflect todays new products and new testing procedures, while the original 21 chapters contained in the seventh edition have been retained and updated. One new chapter, Biodiesel, has been added in response to the worldwide interest in developing renewable fuels. In addition to oxygenates, which are generally blended for gasoline engines, specifications for diesel fuel are being changed to incorporate materials of biological origin for the purpose of sustainability of fuels products. Government regulators are mandating the use of biodiesel fuels (biodiesels) and are presently in discussions with petroleum companies and engine manufacturers to ensure conformance with published timetables for the use of these fuels. Committee D02 has responded with the development of specifications and new test methods, as described in this new chapter. Another new chapter is entitled Synthetic Liquid Fuels. Again, due to the worldwide interest in diminishing dependence on traditional petroleum fuels, research in alternative fuels is being conducted by many organizations including petroleum companies. Specifications and test methods for synthetic fuels are continually being developed by Committee D02 to define the characteristics of these new materials, and these are discussed in the new chapter. The various petroleum products, including crude oils, have always been tested to determine the qualitative and quantitative nature of inorganic substances contained therein. This is discussed in the new chapter Determination of Inorganic Species in Petroleum Products and Lubricants. The techniques used are many and varied, the product and the nature and concentration of the inorganic species. In

1

Consultant, North Fort Myers, FL.

1Copyright by ASTM Int'l (all rights reserved); Mon Apr 11 11:51:23 EDT 2011 Copyright 2010 by ASTM International www.astm.org Downloaded/printed by Univ de los Andes Colombia pursuant to License Agreement. No further reproductions authorized.

2

SIGNIFICANCE OF TESTS FOR PETROLEUM PRODUCTS

n

8TH EDITION

addition, a number of unexpected problems have recently arisen in the field regarding inorganic materials affecting the performance of petroleum fuels. One such problem is the deposition of silicon dioxide on gasoline engine parts due to the contamination of gasoline with very small quantities of silicon. Another problem is the inactivation of silver alloy sensing units in fuel tanks with the use of some low-sulfur gasoline fuels. Still another concern is the deposition of sulfate-containing materials in fuel metering systems and on fuel dispenser filters when certain ethanol batches are blended with gasoline. These problems require methods that measure inorganic contaminants at extremely low levels using new techniques, all of which are under development in Committee D02. Many of the test procedures described in this manual are newer correlative methods, which represent the way of the

future due to their simplicity, objectivity, economy, and, in many cases, portability. Quality assurance methods must be integrated into analytical procedures and protocols, so that we can demonstrate that these methods provide accuracy and precision equal to or better than the referee methods they supersede. A major thrust in analytical chemistry at the present is the development of methods that count individual molecules. While we have not yet achieved this level of sensitivity in the testing of petroleum products, when these new tools do arrive, and they will, we will be able to determine the concentration of an analyte in a petroleum product with 100% accuracy. The chapters that follow show that the technology associated with the testing of petroleum products is advancing at an increasingly rapid rate. They also demonstrate that ASTM International continues to be the foremost standardization organization in the world.


2Lewis M. Gibbs,1 Ben R. Bonazza,2 and Robert L. Furey3AUTOMOTIVE SPARK-IGNITION ENGINE FUEL consists of gasoline or gasoline-oxygenate blends used in internal combustion spark-ignition engines, as opposed to engine fuels used in diesel or compression-ignition engines. These spark-ignition engine fuels are used primarily in passenger car and highway truck service. They are also used in off-highway utility trucks, farm machinery, two- and fourstroke cycle marine engines, and other spark-ignition engines used in a variety of service applications. ASTM D4814, Specification for Automotive SparkIgnition Engine Fuel, defines gasoline as a volatile mixture of liquid hydrocarbons, containing small amounts of additives. A gasoline-oxygenate blend is defined as a fuel consisting primarily of gasoline, along with a substantial amount of one or more oxygenates. An oxygenate is an oxygen-containing, ashless organic compound, such as an alcohol or ether, which can be used as a fuel or fuel supplement. Ethanol is the predominant oxygenate in use today. Spark-ignition engine fuel includes both gasolines and gasoline-oxygenate blends. Gasoline is a complex mixture of relatively volatile hydrocarbons that vary widely in their physical and chemical properties. It is a blend of many hydrocarbons derived from the fractional distillation of crude petroleum and from complex refinery processes that increase either the amount or the quality of gasoline. The hundreds of individual hydrocarbons in gasoline typically range from those having just four carbon atoms (designated C4, composed of butanes and butenes) to those having as many as 11 carbon atoms (designated C11, such as methylnaphthalene). The types of hydrocarbons in gasoline are paraffins, isoparaffins, naphthenes, olefins, and aromatics. The properties of commercial gasolines are predominantly influenced by the refinery practices that are used and partially influenced by the nature of the crude oils from which they are produced. Finished gasolines have a boiling range from about 30 to 225C (86 to 437F) in a standard distillation test. Gasoline may be blended, or may be required to be blended, with oxygenates to improve the octane rating, extend the fuel supply, reduce vehicle exhaust emissions, or comply with regulatory requirements. The oxygenated components of spark-ignition engine fuel include aliphatic ethers, such as methyl tert-butyl ether (MTBE), and alcohols such as ethanol. The ethers are allowed by U.S. Environmental Protection Agency (EPA) regulations to be used in concentrations where they provide not more than 2.7 mass percent oxygen in the final fuel blend. Because of concerns over ground water contamination, MTBE is banned in many states and is no longer widely used in the United States. Ethanol and certain other alcohols may provide not more than 3.7 mass percent oxygen in the fuel.1 2 3

MNL1-EB/May 2010

Automotive Spark-Ignition Engine FuelLegal restrictions exist on the use of methanol in gasoline, and it is not currently intentionally added to any gasolines marketed in the United States. These restrictions will be discussed later. The federal Renewable Fuel Standard (RFS) established under the Energy Independence and Security Act of 2007 requires a national minimum volume usage requirement of ethanol that increases annually until 2022. In addition, a number of states or portions of states mandate that spark-ignition engine fuel contain 10 volume percent ethanol blended with gasoline. Spark-ignition engine fuels are blended to satisfy diverse automotive requirements. In addition, the fuels are exposed to a variety of mechanical, physical, and chemical environments. Therefore, the properties of the fuel must be balanced to give satisfactory engine performance over an extremely wide range of operating conditions. The prevailing standards for fuel represent compromises among the numerous quality, environmental, and performance requirements. Antiknock rating, distillation characteristics, vapor pressure, sulfur content, oxidation stability, corrosion protection, and other properties are balanced to provide satisfactory vehicle performance. In most gasolines, additives are used to provide or enhance specific performance features. In recent years, there has been an ever-growing body of governmental regulations to address concerns about the environment. Initially, most of the regulations were aimed at the automobile and have resulted in technologies that have significantly reduced vehicle emissions. Regulations have also been aimed at compositional changes to the fuels that result in reduced vehicle emissions. The first major change in fuel composition was the introduction of unleaded gasoline in the early 1970s, followed by the phase-down of lead levels in leaded gasoline (19791986). Most passenger cars and light-duty trucks beginning with the 1975 model year have required unleaded fuel. In 1989, the U.S. EPA implemented gasoline volatility regulations. Reductions in fuel vapor pressure limits during the summer were implemented under these regulations, followed by further reductions in 1992. Beginning in 1987, several states required the addition of oxygenates to gasoline during the winter months in certain geographic areas to reduce vehicle carbon monoxide emissions. The added oxygenates are especially effective in reducing carbon monoxide during a cold start with older vehicles. When a vehicle is started cold, the catalyst is inactive and the computer is not controlling the air-fuel ratio in closed-loop mode. Added oxygen in the fuel leans the vehicles fuel mixture, lowering carbon monoxide emissions. The Clean Air Act Amendments of 1990 required additional compositional changes to automotive spark-ignition

Chevron Products Company, Richmond, CA. TI Automotive (retired), Lapeer, MI. Furey & Associates, LLC, Rochester Hills, MI.

3Copyright by ASTM Int'l (all rights reserved); Mon Apr 11 11:51:23 EDT 2011 Copyright 2010 by ASTM International www.astm.org Downloaded/printed by Univ de los Andes Colombia pursuant to License Agreement. No further reproductions authorized.

4


n

8TH EDITION

engine fuels. In November 1992, 39 areas failing to meet the federal standard for carbon monoxide were required to implement oxygenated fuel programs similar to those mentioned previously. There are also provisions in the act that address ozone nonattainment. Beginning in 1995, the use of a cleaner-burning reformulated gasoline was required in the nine worst ozone nonattainment areas. Other ozone nonattainment areas have the option of participating in the program. Federal reformulated gasoline is a gasoline-oxygenate blend certified to meet the specifications and emission reduction requirements established by the Clean Air Act Amendments of 1990; therefore, it would be more correctly referred to as federal reformulated spark-ignition engine fuel. Federal and state regulations frequently use the term gasoline to cover both gasoline and gasoline-oxygenate blends. (See ASTM Committee D02 on Petroleum Products and Lubricants Research Report D02: 1347, Research Report on Reformulated Spark-Ignition Engine Fuel for reformulated gasoline requirements and test methods.) This chapter summarizes the significance of the more important physical and chemical characteristics of automotive spark-ignition engine fuel and describes pertinent test methods for defining or evaluating these properties. Information on governmental requirements is also provided. This discussion applies only to those fuels that can be used in engines designed for spark-ignition engine fuel. It does not include fuels that are primarily oxygenates, such as M85, a blend of 85 volume percent methanol and 15 volume percent gasoline, or E85, a blend of 85 volume percent ethanol and 15 volume percent gasoline, which are for use in flexible fuel vehicles. These fuels and the oxygenates commonly used in gasoline are discussed in detail in Chapter 3. [See ASTM D5797, Specification for Fuel Methanol (M70-M85) for Automotive Spark-Ignition Engines, or ASTM D5798, Specification for Fuel Ethanol (Ed75-Ed85) for Automotive SparkIgnition Engines.]

lead/liter (g Pb/L) [0.05 gram of lead/U.S. gallon (0.05 g Pb/ gal)] and a RON of at least 91. (This was changed to a minimum Antiknock Index of 87 in 1983, and the requirement was dropped in 1991.) Starting in the 1975 model year, most spark-ignition enginepowered automobiles and light-duty trucks required the use of unleaded fuel. With this requirement, low-lead fuels [0.13 g Pb/L (0.5 g Pb/gal)] disappeared. In addition, leaded premium began to be superseded by unleaded premium in the late 1970s and early 1980s. In the mid-1980s, an unleaded midgrade fuel became widely available, and many fuel marketers now offer three grades of unleaded fuel: regular, midgrade, and premium. Lead usage in motor fuels was banned entirely in California effective in 1992 and was banned from all U.S. reformulated fuels in 1995 and from all U.S. motor fuels in 1996. Leaded fuel can still be produced for off-road use and for use as a racing fuel.

ANTIKNOCK RATINGThe definitions and test methods for antiknock rating for automotive spark-ignition engine fuels are set forth in Appendix X1 in ASTM D4814, Specification for Automotive SparkIgnition Engine Fuel. Antiknock rating and volatility are perhaps the two most important characteristics of spark-ignition engine fuel. If the antiknock rating of the fuel is lower than that required by the engine, knock occurs. Knock is a highpitch, metallic rapping noise. Fuel with an antiknock rating higher than that required for knock-free operation generally does not improve performance. However, vehicles equipped with knock sensors may show a performance improvement as the antiknock rating of the fuel is increased, provided that the antiknock rating of the fuel is lower than that required by the engine. Conversely, reductions in fuel antiknock rating may cause a loss in vehicle performance. The loss of power and the damage to an automotive engine due to knocking are generally not significant until the knock intensity becomes severe and prolonged. Knock depends on complex physical and chemical phenomena highly interrelated with engine design and operating conditions. It has not been possible to characterize completely the antiknock performance of spark-ignition engine fuel with any single measurement. The antiknock performance of a fuel is related intimately to the engine in which it is used and the engine operating conditions. Furthermore, this relationship varies from one engine design to another and may even be different among engines of the same design, due to normal production variations. The antiknock rating of a spark-ignition engine fuel is measured in single-cylinder laboratory engines. Two methods have been standardized and are presented in ASTM D2699/ IP 237, Test Method for Research Octane Number of SparkIgnition Engine Fuel, and ASTM D2700/IP 236, Test Method for Motor Octane Number of Spark-Ignition Engine Fuel. Another method used for quality control in fuel blending is given in ASTM D2885/IP 360, Test Method for Research and Motor Method Octane Ratings Using On-Line Analyzers. These single-cylinder engine test procedures use a variablecompression-ratio engine. The Motor method operates at a higher speed and inlet mixture temperature than the Research method. The procedures relate the knocking characteristics of a test fuel to standard fuels, which are blends of two pure hydrocarbons: 2,2,4-trimethylpentane (isooctane) and n-heptane. These blends are called primary reference fuels. By definition, the octane number of isooctane is 100, and the

GRADES OF SPARK-IGNITION ENGINE FUELUntil 1970, with the exception of one brand of premiumgrade fuel marketed on the East Coast and southern areas of the United States, all grades of automotive fuel contained lead alkyl compounds to increase the antiknock rating. The Antiknock Index [the average of the Research Octane Number (RON) and the Motor Octane Number (MON)] of the leaded premium-grade fuel pool increased steadily from about 82 at the end of World War II to about 96 in 1968. During the same time, the Antiknock Index of the leaded regular grade followed a parallel trend from about 77 to 90. Leaded fuel began to be phased out during the 1970s, and in 1996 all lead was banned from highway fuel. In 1971, U.S. passenger car manufacturers began a transition to engines that would operate satisfactorily on fuels with lower octane ratings, namely, a minimum RON of 91. This octane level was chosen because unleaded fuels are needed to prolong the effectiveness of automotive emission catalyst systems and because unleaded fuels of 91 RON could be produced in the required quantities using refinery processing equipment then available. In 1970, fuel marketers introduced unleaded and low-lead fuels of this octane level to supplement the conventional leaded fuels already available. Beginning in July 1974, the U.S. EPA mandated that most service stations have available a grade of unleaded fuel defined as having a lead content not exceeding 0.013 gram of


CHAPTER 2

n

AUTOMOTIVE SPARK-IGNITION ENGINE FUEL

5

octane number of n-heptane is 0. At octane levels below 100, the octane number of a given fuel is the percentage by volume of isooctane in a blend with n-heptane that knocks with the same intensity at the same compression ratio as the fuel when compared by one of the standardized engine test methods. The octane number of a fuel greater than 100 is based on the volume of tetraethyl lead that must be added to isooctane to produce knock with the same intensity as the fuel. The volume of tetraethyl lead in isooctane is converted to octane numbers greater than 100 by use of tables included in the Research and Motor methods. The octane number of a given blend of either isooctane and n-heptane or tetraethyl lead in isooctane is, by definition, the same for the Research and Motor methods. However, the RON and MON will rarely be the same for commercial fuels. Therefore, when considering the octane number of a given fuel, it is necessary to know the engine test method. RON is, in general, the better indicator of antiknock rating for engines operating at full throttle and low engine speed. MON is the better indicator at full throttle, high engine speed, and part throttle, low and high engine speed. The difference between RON and MON is called sensitivity. According to recent surveys of U.S. commercial fuels, the average sensitivity is about 9 units for unleaded regular grade and about 10 units for unleaded premium grade. For most automotive engines and operating conditions, the antiknock performance of a fuel will be between its RON and MON. The exact relationship is dependent on the vehicle and operating conditions. Antiknock Index [the average of RON and MON, that is, (R M)/2] is a currently accepted method of relating RON and MON to actual road antiknock performance in vehicles. U.S. Federal Trade Commission (FTC) regulations require a label on each service station dispensing pump showing the minimum (R M)/2 value of the fuel dispensed. For fuels sold in the United States, regular grade is typically 87 (R M)/2 (often slightly lower at high altitudes), midgrade is typically about 89, and premium is typically 91 or higher. Other grades also exist. The terms used to describe the various grades (e.g., regular, midgrade, super, premium, etc.) vary among fuel marketers and location. With the FTC regulation, a consumer can match the (R M)/2 value specified in the owners manual with the value on the pump. Because octane quality is a marketing issue, ASTM does not specify a minimum Antiknock Index in ASTM D4814.

The volatility of automotive spark-ignition engine fuel must be carefully balanced to provide the optimum compromise among performance features that depend on the vaporization behavior. Superior performance in one respect may give serious trouble in another. Therefore, volatility characteristics of automotive fuel must be adjusted for seasonal variations in atmospheric temperatures and geographic variations in altitude. Four common volatility properties are described later. The effect of these volatility parameters on the performance of the vehicle is also presented.

Vapor PressureOne of the most common measures of fuel volatility is the vapor pressure at 37.8C (100F) measured in a chamber having a 4:1 ratio of air to liquid fuel. ASTM D323, Test Method for Vapor Pressure of Petroleum Products (Reid Method), can be used for hydrocarbon-only gasolines and gasoline-ether blends but not for gasoline-alcohol blends because traces of water in the apparatus can extract the alcohol from the blend and lead to incorrect results. Therefore, this method is no longer listed as an acceptable test method for spark-ignition engine fuels in ASTM D4814. To avoid the alcoholwater interaction problem in Test Method D323, a similar method using the same apparatus and procedure, but maintaining dry conditions, has been developedASTM D4953, Test Method for Vapor Pressure of Gasoline and Gasoline-Oxygenate Blends (Dry Method). The results are reported as Dry Vapor Pressure Equivalent (DVPE) rather than Reid Vapor Pressure (RVP), which is only determined using Test Method D323. For hydrocarbon-only gasolines, there is no statistically significant difference in the results obtained by Test Methods D323 and D4953. Advances in instrumentation have led to the development of three other methods that can be used for both gasolines and gasoline-oxygenate blends. They are ASTM D5190, Test Method for Vapor Pressure of Petroleum Products (Automatic Method), ASTM D5191, Test Method for Vapor Pressure of Petroleum Products (Mini Method), and ASTM D5482, Test Method for Vapor Pressure of Petroleum Products (Mini MethodAtmospheric). The precision (repeatability and reproducibility) of these three methods is much better than that for D4953. Another method, ASTM D6378, Test Method for Determination of Vapor Pressure (VPX) of Petroleum Products, Hydrocarbons, and Hydrocarbon-Oxygenate Mixtures (Triple Expansion Method), is reported to not require air saturation and cooling of the sample before testing. This test method reports results as VPX. An equation is provided in the test method to convert the results to DVPE to determine compliance with Specification D4814 maximum limits. The U.S. EPA and the California Air Resources Board use the D5191 test method. However, each uses a slightly different equation than that used by ASTM to calculate vapor pressure from the instruments total pressure reading. The equation used depends on the brand of the instrument.

VOLATILITYThe volatility characteristics of a spark-ignition engine fuel are of prime importance to the driveability of vehicles under all conditions encountered in normal service. The large variations in operating conditions and wide ranges of atmospheric temperatures and pressures impose many limitations on a fuel if it is to give satisfactory vehicle performance. Fuels that vaporize too readily in pumps, fuel lines, carburetors, or fuel injectors will cause decreased fuel flow to the engine, resulting in hard starting, rough engine operation, or stoppage (vapor lock). Under certain atmospheric conditions, fuels that vaporize too readily can also cause ice formation in the throat of a carburetor, resulting in rough idle and stalling. This problem occurs primarily in older cars. Conversely, fuels that do not vaporize readily enough may cause hard starting and poor warm-up driveability and acceleration. These low-volatility fuels may also cause an unequal distribution of fuel to the individual cylinders.

DistillationThe tendency of a fuel to vaporize is also characterized by determining a series of temperatures at which various percentages of the fuel have evaporated, as described in ASTM D86, Test Method for Distillation of Petroleum Products at Atmospheric Pressure. A plot of the results is commonly called the distillation curve. The 10, 50, and 90 volume percent evaporated temperatures are often used to characterize


6


n

8TH EDITION

the volatility of spark-ignition engine fuel. The fuel also can be characterized by reporting the percentage evaporated at specified temperatures (e.g., E100). Two gas chromatography test methods that can be used to determine the distillation characteristics are ASTM D3710, Test Method for Boiling Range Distribution of Gasoline and Gasoline Fractions by Gas Chromatography, and D7096, Test Method for Determination of the Boiling Range Distribution of Gasoline by Wide-Bore Capillary Gas Chromatography. Two distillation test methods requiring considerably smaller sample sizes than Test Method D86 are D7344, Test Method for Distillation of Petroleum Products at Atmospheric Pressure (Mini Method), and D7345, Test Method for Distillation of Petroleum Products at Atmospheric Pressure (Micro Distillation Method). To improve the correlation of reported results with those of Test Method D86, bias corrections are provided.

Volatility and PerformanceIn general terms, the following relationships between volatility and performance apply: 1. High vapor pressures and low 10 % evaporated temperatures are both conducive to ease of cold starting. However, under hot operating conditions, they are also conducive to vapor lock and increased vapor formation in fuel tanks, carburetors, and fuel injectors. The amount of vapor formed in fuel tanks and carburetors, which must be contained by the evaporative emissions control system, is related to the vapor pressure and distillation temperatures. Thus, a proper balance of vapor pressure and 10 % evaporated temperature must be maintained and seasonally adjusted for good overall performance. 2. Although vapor pressure is a factor in the amount of vapor formed under vapor locking conditions, vapor pressure alone is not a good index. A better index for measuring the vapor locking performance of spark-ignition engine fuels is the temperature at which the V/L is 20 at atmospheric pressure. The lower the temperature at which V/L 20, the greater is the tendency to cause vapor lock and hot-fuelhandling driveability problems. Vapor lock is much less of a problem for fuel-injected cars, which have pressurized fuel systems. However, driveability symptoms are similar to carbureted vehicles; a toovolatile fuel in fuel-injected cars can cause hard starting and rough idling, and in the extreme, the car will not start. 3. The distillation temperature at which 50 % of the fuel has evaporated is a broad indicator of warm-up and acceleration performance under cold-starting conditions. The lower the 50 % evaporated temperature, the better is the performance. (This statement is not always valid for gasoline-oxygenate blends, especially those containing alcohol.) The temperatures for 10 and 90 % evaporated are also indicators of warm-up performance under cold-starting conditions, but to a lesser degree than the 50 % evaporated temperature. Lowering the 50 % evaporated point, within limits, also has been shown to reduce exhaust hydrocarbon emissions. 4. The temperatures for 90 % evaporated and the final boiling point, or end point, indicate the amount of relatively high-boiling components in gasoline. A high 90 % evaporated temperature, because it is usually associated with higher density and high-octane number components, may contribute to improved fuel economy and resistance to knock. If the 90 % evaporated temperature and the end point are too high, they can cause poor mixture distribution in the intake manifold and combustion chambers, increased hydrocarbon emissions, excessive combustion chamber deposits, and dilution of the crankcase oil. 5. DI represents the entire distillation curve. Lower values of DI mean greater volatility, which equates to better coldstart and warm-up driveability until some minimum level is reached where no further improvement is observed. If the DI is too high, vehicle cold-start and warm-up driveability can be adversely affected. Maximum DI for each volatility class is limited by ASTM D4814 and other specifications developed by motor vehicle manufacturers and by fuel suppliers. A DI specification limit allows a refiner more flexibility in blending spark-ignition engine fuel that provides proper cold-start and warm-up driveability, compared to tight restrictions on individual distillation points. As ambient temperature is reduced, fuels with lower DI

Driveability IndexWhile each area of the distillation curve is important, the combination of the various points that describe the whole curve must be taken into account to describe adequately vehicle driveability. The ASTM Driveability Task Force, using data from the Coordinating Research Council (CRC) and others, has developed a correlation between various distillation points and vehicle cold-start and warm-up driveability. This correlation is called Driveability Index (DI) and is defined as: DI 1.5 3 T10 3.0 3 T50 1.0 3 T90 1.33C (2.4F) 3 Ethanol Volume percent, where T10, T50, and T90 are the temperatures at the 10, 50, and 90 % evaporated points of a Test Method D86 distillation, respectively; 1.33 is the coefficient for the volume percent ethanol present when the distillation results are determined in degrees Celsius; and 2.4 is the coefficient when distillation results are determined in degrees Fahrenheit. The ethanol correction term is required because the reduction in the T50 resulting from the addition of ethanol does not provide as much improvement in driveability as would such a reduction by a hydrocarbon.

Vapor-Liquid RatioThe vaporization tendency of spark-ignition engine fuel can also be expressed in terms of vapor-to-liquid ratio (V/L) at temperatures approximating those found in critical parts of the fuel system. The standard test method is ASTM D5188, Test Method for Vapor-Liquid Ratio Temperature Determination of Fuels (Evacuated Chamber Method). This method is applicable to samples for which the determined temperature is between 36 and 80C and the V/L is between 8:1 and 75:1. The fuel temperature at a V/L of approximately 20 (TV/L20) was shown to be indicative of the tendency of a fuel to cause vapor lock, as evidenced by loss of power during full-throttle accelerations. V/Ltemperature relationships were originally developed for vehicles equipped with carburetors and suction-type fuel pumps. The applicability of such relationships to late-model vehicles equipped with fuel injection and pressurized fuel systems has been shown by CRC test programs. Appendix X2 of ASTM D4814 includes a computer method and a linear equation method that can be used for estimating V/L of spark-ignition engine fuels from vapor pressure and distillation test results. However, until recently these estimation methods were not applicable to gasoline-oxygenate blends. ASTM D4814 in Appendix X2 now provides equations for correcting the estimated values applicable to ethanol blends.


CHAPTER 2

n


7

are required. The impact of oxygenates on DI and driveability is not well established. Some testing has shown that at the same DI level, poorer driveability occurs with oxygenated fuels. Other data have not shown this effect. The oxygenate effect may depend on the ambient temperature, type of oxygenate, and DI level of the fuel. The DI equation now contains a correction for ethanol blends. The CRC continues to investigate this issue. ASTM D4814, Specification for Automotive Spark-Ignition Engine Fuel, includes a table of six volatility classes for vapor pressure, distillation temperatures, and DI, and a separate vapor lock protection table of six volatility classes for TV/L20. A combination of limits from these two tables defines the fuel volatility requirements for each month and geographic area of the United States. The specification also accounts for the EPA regulations on vapor pressure and state implementation plan (SIP) vapor pressure limits approved by the EPA. These volatility characteristics have been established on the basis of broad experience and cooperation between fuel suppliers and manufacturers and users of automotive vehicles and equipment. Spark-ignition engine fuels meeting this specification have usually provided satisfactory performance in typical passenger car service. However, certain equipment or operating conditions may require or permit variations from these limits. Modern vehicles, designed to exacting tolerances for good emission control, fuel economy, and driveability, may require more restrictive limits.

Lead ContentConstraints imposed by emission control regulations and health concerns have led to the exclusive availability of unleaded fuels for street and highway use. Leaded fuel is still allowed for nonroad use, such as for farm equipment and for racing. The lead content of unleaded fuel is limited to a maximum of 0.013 g Pb/L (0.05 g Pb/gal), but typical lead contents in U.S. unleaded fuels are 0.001 g Pb/L or less. Although the EPA regulations prohibit the deliberate addition of lead to unleaded fuels, some contamination by small amounts of lead can occur in the distribution system. Such occurrences are rare, because leaded fuel has been eliminated from the market. The following methods are suitable for determining the concentration of lead in spark-ignition engine fuel:

FOR LEADED FUELASTM D3341, Test Method for Lead in GasolineIodine Monochloride Method ASTM D5059/IP 228, Test Methods for Lead in Gasoline by X-Ray Spectroscopy

FOR UNLEADED FUELASTM D3237, Test Method for Lead in Gasoline by Atomic Absorption Spectroscopy ASTM D3348, Test Method for Rapid Field Test for Trace Lead in Unleaded Gasoline (Colorimetric Method) ASTM D5059/IP 228, Test Methods for Lead in Gasoline by X-Ray Spectroscopy

OTHER PROPERTIESIn addition to providing acceptable antiknock performance and volatility characteristics, automotive spark-ignition engine fuels must also provide for satisfactory engine and fuel system cleanliness and durability. The following properties have a direct bearing on the overall performance of a fuel.

Phosphorus ContentIn the past, phosphorus compounds were sometimes added to leaded fuels as combustion chamber deposit modifiers. However, because phosphorus adversely affects exhaust emission control system components, particularly the catalytic converter, today EPA regulations limit its concentration in unleaded fuel to a maximum of 0.0013 g P/L (0.005 g P/gal). Furthermore, phosphorus may not be intentionally added to unleaded fuel in any concentration. The concentration of phosphorus can be determined by ASTM D3231, Test Method for Phosphorus in Gasoline.

Workmanship and ContaminationA finished fuel is expected to be visually free of undissolved water, sediment, and suspended matter. It should be clear and bright when observed at 21C (70F). It should also be free of any adulterant or contaminant that may render the fuel unacceptable for its commonly used applications. Physical contamination may occur during refining or distribution of the fuel. Control of such contamination is a matter requiring constant vigilance by refiners, distributors, and marketers. Solid and liquid contamination can lead to restriction of fuel metering orifices, corrosion, fuel line freezing, gel formation, filter plugging, and fuel pump wear. ASTM D2709, Test Method for Water and Sediment in Distillate Fuels by Centrifuge, or ASTM D2276/IP 216, Test Method for Particulate Contaminant in Aviation Fuel by Line Sampling, can be used to determine the presence of contaminants. Appendix X6 of ASTM D4814 contains a recommendation that all fuel dispensers be equipped with filters of 10-micron (micrometer) or less nominal pore size at point of delivery to the customer. Petroleum products pick up microbes during refining, distribution, and storage. Most growth takes place where fuel and water meet. Therefore, it is most important to minimize water in storage tanks. Microbial contamination in fuel was not much of a problem until lead was removed. Appendix X5 of ASTM D4814 discusses microbial contamination and references ASTM D6469, Guide for Microbial Contamination in Fuels and Fuel Systems.

Manganese ContentIn the 1970s, methylcyclopentadienyl manganese tricarbonyl (MMT) was added to some unleaded fuels for octane improvement. However, the use of MMT was banned in 1977 in California. In October 1978, the EPA banned its use in unleaded fuel throughout the United States because it increased vehicle hydrocarbon emissions in various test programs, including the 63-vehicle CRC program in 1977. In 1995, after much testing and court action, MMT was granted a waiver by the EPA for use at a maximum concentration of 0.008 g Mn/L (0.031 g Mn/ gal). According to the EPAs website, the Agency determined that MMT added at 1/32 gpg Mn will not cause or contribute to regulated emissions failures of vehicles. Nevertheless, the use of MMT remains controversial. The EPAs website notes the agencys uncertainty about the health risks of using MMT. The manganese content of spark-ignition engine fuel can be determined by ASTM D3831, Test Method for Manganese in Gasoline by Atomic Absorption Spectroscopy.

Sulfur ContentCrude petroleum contains sulfur compounds, most of which are removed during refining. The maximum amount of sulfur as specified in ASTM D4814 is 0.0080 mass percent,


8


n

8TH EDITION

which is the federal per-gallon maximum limit. The federal regulations also have a refinery annual average maximum limit of 0.0030 mass percent. There are a few exceptions for qualified refineries that expire by the end of 2010. Sulfur oxides formed during combustion may be converted to acids that promote rusting and corrosion of engine parts and exhaust systems. Sulfur oxides formed in the exhaust are undesirable atmospheric pollutants. However, the contribution of automotive exhaust to total sulfur oxide emissions is negligible. Sulfur also reduces the effectiveness of exhaust gas catalytic converters. In 1996, California set an average maximum limit of 0.0030 mass percent and then at the end of 2003 lowered it to 0.0015 mass percent. More details on sulfur requirements are presented later in this chapter. The sulfur content of spark-ignition engine fuel can be determined by the following methods: ASTM D1266/IP 107, Test Method for Sulfur in Petroleum Products (Lamp Method) ASTM D2622, Test Method for Sulfur in Petroleum Products by Wavelength Dispersive X-Ray Fluorescence Spectrometry ASTM D3120, Test Method for Trace Quantities of Sulfur in Light Liquid Hydrocarbons by Oxidative Microcoulometry ASTM D4045, Test Method for Sulfur in Petroleum Products by Hydrogenolysis and Rateometric Colorimetry ASTM D4294, Test Method for Sulfur in Petroleum and Petroleum Products by Energy-Dispersive X-Ray Fluorescence Spectrometry ASTM D5453, Test Method for Determination of Total Sulfur in Light Hydrocarbons, Spark Ignition Engine Fuel and Engine Oil by Ultraviolet Fluorescence ASTM D6334, Test Method for Sulfur in Gasoline by Wavelength Dispersive X-Ray Fluorescence ASTM D6445, Test Method for Sulfur in Gasoline by Energy-Dispersive X-Ray Fluorescence Spectrometry ASTM D6920, Test Method for Total Sulfur in Naphthas, Distillates, Reformulated Gasolines, Diesels, Biodiesels, and Motor Fuel by Oxidative Combustion and Electrochemical Detection ASTM D7039, Test Method for Sulfur in Gasoline and Diesel Fuel by Monochromatic Wavelength Dispersive XRay Fluorescence Spectrometry It is important to review the sulfur content determination minimum and maximum levels before selecting a test method to ensure it is applicable for the test sample of interest. The presence of free sulfur or reactive sulfur compounds can be detected by ASTM D130/IP 154, Test Method for Detection of Copper Corrosion from Petroleum Products by the Copper Strip Tarnish Test, or by ASTM D4952, Test Method for Qualitative Analysis for Active Sulfur Species in Fuels and Solvents (Doctor Test). Sulfur in the form of mercaptans can be determined by ASTM D3227/IP 342, Test Method for (Thiol Mercaptan) Sulfur in Gasoline, Kerosene, Aviation Turbine, and Distillate Fuels (Potentiometric Method).

ASTM D381/IP 131, Test Method for Gum Content in Fuels by Jet Evaporation, is used to determine gum content. Many fuels are deliberately blended with nonvolatile oils or additives or both, which remain as residues in the evaporation step of the gum test. A heptane-washing step is, therefore, a necessary part of the procedure to remove such materials, so that the solvent washed gum may be determined. The unwashed gum content (determined before the heptanes-washing step) indicates the presence of nonvolatile oils or additives. ASTM Test Method D381/IP 131 also is used to determine the unwashed gum content. There is no specification limit for unwashed gum content in ASTM D4814. Automotive fuels usually have a very low gum content when manufactured but may oxidize to form gum during extended storage. ASTM D525/IP 40, Test Method for Oxidation Stability of Gasoline (Induction Period Method), is a test to indicate the tendency of a fuel to resist oxidation and gum formation. It should be recognized, however, that the methods correlation with actual field service may vary markedly under different storage conditions and with different fuel blends. Most automotive fuels contain special additives (antioxidants) to prevent oxidation and gum formation. Some fuels also contain metal deactivators for this purpose. Commercial fuels available in service stations move rather rapidly from refinery production to vehicle usage and are not designed for extended storage. Fuels purchased for severe bulk storage conditions or for prolonged storage in vehicle fuel systems generally have additional amounts of antioxidant and metal deactivator added. Although not designed for automotive fuel, ASTM D873, Test Method for Oxidation Stability of Aviation Fuels (Potential Residue Method), is sometimes used to evaluate the stability of fuel under severe conditions, and like ASTM D525, it can indicate the tendency of the fuel to oxidize. No correlation has been established between the results of this test and actual automotive service, but the comparative rankings of fuels tested by D873 are often useful. Peroxides are undesirable in automotive fuel because they can attack fuel system elastomers and copper commutators in fuel pumps. Peroxides can participate in an autocatalytic reaction to form more peroxides, thus accelerating the deterioration of fuel system components. Also, peroxides reduce the octane rating of the fuel. Hydroperoxides and reactive peroxides can be determined by ASTM D3703, Test Method for Peroxide Number of Aviation Turbine Fuels, or by ASTM D6447, Test Method for Hydroperoxide Number of Aviation Turbine Fuels by Voltammetric Analysis.

Density and Relative DensityASTM D4814 does not set limits on the density of spark-ignition engine fuels, because the density is fixed by the other chemical and physical properties of the fuel. Density relates to the volumetric energy content of the fuelthe more dense the fuel, the higher is the volumetric energy content. Density is important, also, because fuel is often bought and sold with reference to a specific temperature, usually 15.6C (60F). Because the fuel is usually not at the specified temperature, volume correction factors based on the change in density with temperature are used to correct the volume to that temperature. Volume correction factors for oxygenates differ somewhat from those for hydrocarbons, and work is in progress to determine precise correction factors for gasoline-oxygenate blends. Rather than using absolute density (in units of kg/m3, for example), relative density is often used. Relative density, or

Gum and StabilityDuring storage, fuels can oxidize slowly in the presence of air and form undesirable oxidation products such as peroxides and/or gum. These products are usually soluble in the fuel, but the gum may appear as a sticky residue on evaporation. These residues can deposit on carburetor surfaces, fuel injectors, and intake manifolds, valves, stems, guides, and ports. ASTM D4814 limits the solvent-washed gum content of spark-ignition engine fuel to a maximum of 5 mg/100 mL.


CHAPTER 2

n


9

specific gravity, is the ratio of the mass of a given volume of fuel at a given temperature to the mass of an equal volume of water at the same temperature. Most automotive fuels have relative densities between 0.70 and 0.78 at 15.6C (60F). The American Petroleum Institute (API) gravity is often used as a measure of a fuels relative density, although this practice is now discouraged with the move toward the use of SI units. API gravity is based on an arbitrary hydrometer scale and is related to specific gravity at 15.6C (60F) as follows: API Gravity; Deg: 141:5 131:5 sp gr15:6=15:6 C 1

Fuel density is determined by ASTM D1298/IP 160, Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method, or by ASTM D4052/IP 365, Test Method for Density and Relative Density of Liquids by Digital Density Meter.

Rust and CorrosionFilter plugging and engine wear problems are reduced by minimizing rust and corrosion in fuel distribution and vehicle fuel systems. Modifications of ASTM D665/IP 135, Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water, are sometimes used to measure rust protection of fuels.

Silver CorrosionReactive trace sulfur compounds (elemental sulfur, hydrogen sulfide, and mercaptans) present in fuel under some circumstances can corrode or tarnish silver alloy fuel gage intank sending units, causing them to fail. To minimize the failure of the silver fuel gage sending units, the fuel must pass the silver corrosion test method described in Annex A1 in ASTM Specification D4814. The test method uses the ASTM Test Method D130 test apparatus except a silver coupon replaces the normal copper one. ASTM is working to develop a new silver corrosion test method. ASTM D4814 limits the silver corrosion rating to a maximum of 1.

The amount of benzene can be determined by ASTM D4053, Test Method for Benzene in Motor and Aviation Gasoline by Infrared Spectroscopy. The amounts of benzene and other aromatics can be determined by ASTM D3606, Test Method for Benzene and Toluene in Finished Motor and Aviation Gasoline by Gas Chromatography, although there are interferences from methanol and ethanol. ASTM D5580, Test Method for the Determination of Benzene, Toluene, Ethylbenzene, p/m-Xylene, o-Xylene, C9 and Heavier Aromatics, and Total Aromatics in Finished Gasoline by Gas Chromatography, and ASTM D5769, Test Method for Determination of Benzene, Toluene, and Total Aromatics in Finished Gasoline by Gas Chromatography/Mass Spectrometry, can also be used. Another method for the determination of aromatics is ASTM D5986, Test Method for Determination of Oxygenates, Benzene, Toluene, C8-C12 Aromatics and Total Aromatics in Finished Gasoline by Gas Chromatography/Fourier Transform Infrared Spectroscopy. The benzene content of reformulated gasoline is limited to 1 volume percent by legislation, because benzene is considered toxic and a carcinogen. Beginning in 2011 under the Mobile Source Air Toxics (MSAT) Rule, benzene will be controlled for all gasoline at a refinery maximum average of 0.62 volume percent with a credit and trading program. The total olefin content of automotive fuel can be determined by ASTM D6296, Test Method for Total Olefins in Spark-Ignition Engine Fuels by Multi-dimensional Gas Chromatography, or by ASTM D6550, Test Method for Determination of Olefin Content of Gasolines by Supercritical-Fluid Chromatography. The latter method has recently been designated by the California Air Resources Board as their standard test method for olefins.

OxygenatesOxygenates are discussed in detail later in this chapter, and additional information on oxygenates is presented in Chapter 3. Nevertheless, it is appropriate to mention here that alcohols or ethers are often added to gasoline to improve octane rating, extend the fuel supply, or reduce vehicle emissions. Certain governmental regulations require such addition, as will be discussed. Consequently, it is often necessary to determine the oxygenate content or the oxygen content of sparkignition engine fuels. ASTM D4815, Test Method for Determination of MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcohol and C1 to C4 Alcohols in Gasoline by Gas Chromatography, can be used to determine the identity and concentrations of low-molecular-weight aliphatic alcohols and ethers. Alternative methods for determining the amounts of oxygenates are ASTM D5599, Test Method for Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame Ionization Detection, and ASTM D5845, Test Method for Determination of MTBE, ETBE, TAME, DIPE, Methanol, Ethanol and tert-Butanol in Gasoline by Infrared Spectroscopy. Appendix X4 in Specification D4814 describes a procedure for calculating the oxygen content of the fuel from the oxygenate content.

Hydrocarbon CompositionThe three major types of hydrocarbons in gasoline are the saturates (paraffins, isoparaffins, naphthenes), olefins, and aromatics. They are identified by ASTM D1319/IP 156, Test Method for Hydrocarbon Types in Liquid Petroleum Products by Fluorescent Indicator Adsorption. This method ignores oxygenates in the fuel and only measures the percentages of saturates, olefins, and aromatics in the hydrocarbon portion of the fuel. Therefore, the results must be corrected for any oxygenates that are present. ASTM D6293, Test Method for Oxygenates and Paraffin, Olefin, Naphthene, Aromatic (O-PONA) Hydrocarbon Types in Low-Olefin Spark Ignition Engine Fuel by Gas Chromatography, is another method. A more detailed compositional analysis can be determined using one of the following methods: ASTM D6729, Test Method for Determination of Individual Components in Spark Ignition Engine Fuels by 100 Metre Capillary High Resolution Gas Chromatography, ASTM D6730, Test Method for Determination of Individual Components in Spark Ignition Engine Fuels by 100 Metre Capillary (with Precolumn) High Resolution Gas Chromatography, or ASTM D6733, Test Method for Determination of Individual Components in Spark Ignition Engine Fuels by 50 Metre Capillary High Resolution Gas Chromatography.

AdditivesFuel additives are used to provide or enhance various performance features related to the satisfactory operation of engines, as well as to minimize fuel handling and storage problems. These chemicals complement refinery processing in attaining the desired level of product quality. The most commonly used additives are listed in Table 1. With few


10


n

8TH EDITION

TABLE 1Commercial Spark-Ignition Engine Fuel AdditivesClass Oxidation inhibitors (antioxidants) Corrosion inhibitors Silver corrosion inhibitors Metal deactivators Carburetor/injector detergents Deposit control additives Function Minimize oxidation and gum formation Inhibit ferrous corrosion in pipelines, storage tanks, and vehicle fuel systems Inhibit corrosion of silver fuel gage sender units Inhibit oxidation and gum formation catalyzed by ions of copper and other metals Prevent and remove deposits in carburetors and port fuel injectors Remove and prevent deposits throughout fuel injectors, carburetors, intake ports and valves, and intake manifold Minimize emulsion formation by improving water separation Minimize engine stalling and starting problems by preventing ice formation in the carburetor and fuel system Improve octane quality of automotive fuel Identification of automotive fuel Additive Type Aromatic amines and hindered phenols Carboxylic acids and carboxylates Substituted thiadiazole Chelating agent Amines, amides, and amine carboxylates Polybutene amines and polyether amines

Demulsifiers Anti-icing additives

Polyglycol derivatives Surfactants, alcohols, and glycols

Antiknock compounds Dyes, markers

Lead alkyls and methylcyclopentadienyl manganese tricarbonyl Oil-soluble solid and liquid dyes, organic fluorescent compounds

Note. Some materials are multifunctional or multipurpose additives, performing more than one function. Source: SAE J312-Automotive Gasolines, Society of Automotive Engineers, Inc.

exceptions, standardized test methods are not available to determine the identity and concentration of specific additives. As mentioned previously, standard test methods are available for determining lead, manganese, and oxygenate content.

U.S. LEGAL REQUIREMENTS FOR SPARK-IGNITION ENGINE FUELFuel CompositionThe U.S. EPA has established vehicle exhaust and evaporative emissions standards as part of the U.S. effort to attain acceptable ambient air quality. To meet these EPA vehicle requirements, extensive modifications have been made to automotive engines and emissions systems. Because some fuel components can harm the effectiveness of vehicle emissions control systems, the EPA also exercises control over automotive fuels. EPA regulations on availability of unleaded automotive fuels, and on limits of lead, phosphorus, and manganese contents in the fuel, have been mentioned. In addition, the Clean Air Act Amendments of 1977 prohibit the introduction into U.S. commerce, or increases in the concentration of, any fuel or fuel additive for use in 1975 and later light-duty motor vehicles, which is not substantially similar to the fuel or fuel additives used in the emissions certification of such vehicles. The EPA considers fuels to be substantially similar if the following criteria are met: 1. The fuel must contain carbon, hydrogen, and oxygen, nitrogen, and/or sulfur, exclusively, in the form of some combination of the following: a. Hydrocarbons b. Aliphatic ethers

Aliphatic alcohols other than methanol (i) Up to 0.3 % methanol by volume (ii) Up to 2.75 % methanol by volume with an equal volume of butanol or higher-molecularweight alcohol d. A fuel additive at a concentration of no more than 0.25 % by weight, which contributes no more than 15 ppm sulfur by weight to the fuel. 2. The fuel must contain no more than 2.0 % oxygen by weight, except fuels containing aliphatic ethers and/or alcohols (excluding methanol) and must contain no more than 2.7 % oxygen by weight. (Note. As mentioned previously, ethanol and certain other alcohols have received waivers allowing as much as 3.7 % oxygen in the fuel.) 3. The fuel must possess, at the time of manufacture, all of the physical and chemical characteristics of an unleaded gasoline, as specified by ASTM Standard D4814-88, for at least one of the Seasonal and Geographical Volatility Classes specified in the standard. (Note. The EPAs February 11, 1991, notice specified the 1988 version of D4814.) 4. The fuel additive must contain only carbon, hydrogen, and any one or all of the following elements: oxygen, nitrogen, and/or sulfur. Fuels or fuel additives that are not substantially similar may only be used if a waiver of this prohibition is obtained from the EPA. Manufacturers of fuels and fuel additives must apply for such a waiver and must establish to the satisfaction of the EPA that the fuel or additive does not cause or contribute to a failure of any emission control device or system over the useful life of the vehicle for which it was certified. Under prior law, if the EPA Administrator had not acted to grant or

c.


CHAPTER 2

n


11

deny the waiver within 180 days after its filing, the waiver was treated as granted. The waiver process has been changed to now require the EPA to act within 270 days. The EPA has granted several waivers for gasoline-oxygenate blends. The reader is referred to the EPA for the latest information on waivers and the conditions under which they may be used. Any fuel or fuel additive that had a waiver as of May 27, 1994, has to have had a supplemental registration with additional toxics data by November 27, 1994, to continue marketing the material. These registered products are subjected to a three-tier toxicological testing program. A new fuel or additive that was not registered as of May 27, 1994, will not be registered until all Tier 1 and Tier 2 information has been supplied. At present, no methanol-containing fuel additive has obtained a supplemental registration, and therefore, the addition of methanol to gasoline is prohibited.

cap by 2007. Refiners demonstrating a severe economic hardship may apply for an extension of up to two years. The regulations provide for some special sulfur limit exemptions for small refineries relating to the early introduction of ultralow sulfur diesel fuel, but these all expire at the end of 2010. The regulations include an averaging program. Some states include fuel sulfur limits in their SIPs.

Sampling, Containers, and Sample HandlingCorrect sampling procedures are critical to obtain a sample representative of the lot intended to be tested. ASTM D4057, Practice for Manual Sampling of Petroleum and Petroleum Products, provides several procedures for manual sampling. ASTM D4177, Practice for Automatic Sampling of Petroleum and Petroleum Products, provides automatic sampling procedures. For volatility determinations of a sample, ASTM D5842, Practice for Sampling and Handling of Fuels for Volatility Measurement, contains special precautions for sampling and handling techniques to maintain sample integrity. ASTM D4306, Practice for Aviation Fuel Sample Containers for Tests Affected by Trace Contamination, should be used to select appropriate containers, especially for tests sensitive to trace contamination. Also ASTM D5854, Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products, provides procedures for container selection and sample mixing and handling. For octane number determination, protection from light is important. Collect and store fuel samples in an opaque container, such as a dark brown glass bottle, metal can, or minimally reactive plastic container, to minimize exposure to UV emissions from sources such as sunlight or fluorescent lamps.

VolatilityConcerns over increased evaporative emissions prompted the EPA to promulgate regulations that, beginning in 1989, reduced fuel vapor pressure. Spark-ignition engine fuels sold between June 1 and September 15 of each year were limited to maximum vapor pressures of 9.0, 9.5, or 10.5 psi, depending on the month and the region of the country. (Vapor pressure restrictions applied to fuels in the distribution system as early as May 1.) In 1992, the EPA implemented Phase II of the volatility controls, which limited fuels sold between June 1 and September 15 to a maximum vapor pressure of 9.0 psi. The regulations are more restrictive in ozone nonattainment areas in the southern and western areas of the United States, where fuels sold during certain months of the control period are limited to a maximum vapor pressure of 7.8 psi. The EPA permits conventional (i.e., not reformulated) fuels containing between 9 and 10 volume percent ethanol to have a vapor pressure 1.0 psi higher than the maximum limit for other fuels. California was the first state to control spark-ignition engine fuel vapor pressure and, in 1971, mandated a maximum vapor pressure limit of 9.0 psi. By 1992, the maximum vapor pressure limit was lowered to 7.8 psi. In 1996, it was further lowered to 7.0 psi maximum. A number of other states have set maximum limits on vapor pressure in certain areas as part of their SIPs. The EPA vapor pressure limits and the EPA-approved SIP limits are an integral part of ASTM D4814.

Oxygenated Fuel Programs and Reformulated Spark-Ignition Engine FuelIn January 1987, Colorado became the first state to mandate the use of oxygenated fuels in certain areas during the winter months to reduce vehicle carbon monoxide (CO) emissions. By 1991, areas in Arizona, Nevada, New Mexico, and Texas had also implemented oxygenated-fuels programs. The 1990 amendments to the Clean Air Act require the use of oxygenated fuels in 39 CO nonattainment areas during the winter months, effective November 1992. The program had to be implemented by the states using one of the following options. If averaging is allowed, the average fuel oxygen content must be at least 2.7 mass percent, with a minimum oxygen content of 2.0 mass percent in each gallon of fuel. Without averaging, the minimum oxygen content of each fuel must be 2.7 mass percent. (This is equivalent to about 7.3 volume percent ethanol or 15 volume percent MTBE.) The first control period was November 1, 1992, through January or February 1993, depending on the area. Subsequent control periods can be longer in some areas. Over time a number of states have come into conformance with CO regulations, and only about eight states still require wintertime ethanol requirements. Beginning in 1995, the nine areas with the worst ozone levels, designated as extreme or severe, were required to sell reformulated spark-ignition engine fuel. Later four additional areas were added, but two are still pending implementation. Areas with less severe ozone levels were permitted to participate in (opt-in to) the program. Initially, about 37 other ozone nonattainment areas opted into participating in the program. Since then, about 17 have chosen to opt-out of the

Sulfur RegulationsCalifornias Phase 2 reformulated gasoline specification limited the maximum sulfur content of fuel to 30 ppm average, with an 80 ppm cap. On December 31, 2003, new Phase 3 specifications lowered the sulfur maximum to 15 ppm average and the cap limits to 60 ppm. The cap limits were further reduced to 30 ppm on December 31, 2005. Federal Tier 2 regulations required that in 2004, refiners meet an annual corporate average sulfur level of 120 ppm, with a cap of 300 ppm. In 2005, the required refinery average was 30 ppm, with a corporate average of 90 ppm and a cap of 300 ppm. Both of the average standards can be met with the use of credits generated by other refiners who reduce sulfur levels early. Beginning in 2006, refiners were required to meet a final 30 ppm average with a cap of 80 ppm. Fuel produced for sale in parts of the western United States must comply with a 150-ppm refinery average and a 300-ppm cap through 2006 but are required to meet the 30-ppm average/80-ppm


12


n

8TH EDITION

program. The reformulated fuel program is directed toward reducing ground level ozone and toxics concentrations. The Clean Air Act Amendments of 1990 set specific guidelines for reformulated spark-ignition engine fuel for 1995 through 1997. Fuels sold in the control areas were required to meet the specifications of what is called the Simple Model. Limits were established for vapor pressure (June 1 through September 15) and benzene content, deposit control additives were required in all fuels, and the use of heavy-metal additives was prohibited. A minimum oxygen content of 2.0 mass percent was required all year (averaged). The sulfur and olefin contents and the 90 % evaporated temperature were not allowed to exceed 125 % of the average values of the refiners 1990 fuels. The use of the Simple Model expired December 31, 1997. Effective January 1, 1998, a Complex Model had to be used for determining conformance to standards for reformulated fuel blends. Fuel properties in the Complex Model included vapor pressure, oxygen content, aromatics content, benzene content, olefins content, sulfur content, E200 and E300 (distillation properties), and the particular oxygenate used. The benzene limit, the ban on heavy metals, the minimum oxygen content, and the requirement for a deposit control additive remained the same as under the Simple Model. As a result of the adoption of the RFS, the minimum oxygen requirement for reformulated fuel was eliminated effective in 2006. The Clean Air Act Amendments of 1990 also contain an antidumping provision. In the production of reformulated spark-ignition engine fuel, a refiner cannot dump into its conventional fuel pool those polluting components removed from the refiners reformulated fuel. These requirements apply to all fuel produced, imported, and consumed in the United States and its territories. In 1992, California instituted its Phase 1 fuel regulations, which were followed in 1996 by its Phase 2 reformulated fuel regulations. The Phase 2 specifications controlled vapor pressure, sulfur content, benzene content, aromatics content, olefins content, 50 % evaporated point, and 90 % evaporated point. These same variables were used in Californias Predictive Model, which is similar to the federal Complex Model, but with different equations. Beginning December 31, 2003, California required fuel to meet a Phase 3 reformulated fuel regulation. An excellent source of information on reformulated fuels (federal and California) and their associated requirements can be found in the ASTM Committee D02 on Petroleum Products and Lubricants Research Report D02: 1347, Research Report on Reformulated Spark-Ignition Engine Fuel for current federal and state future reformulated fuel (cleaner burning fuels) requirements and approved test methods.

the Energy Independence and Security Act (EISA) of 2007, the amount of renewable fuels required was increased to 15.2 billion gallons per year in 2012 and ends with a requirement of 36.0 billion gallons per year by 2022. The proportional requirement for cellulosic biofuel in the act begins in 2010 and scales up to 16.0 billion gallons per year by 2022.

Deposit Control Additive RequirementsCalifornia in 1992 and the EPA in 1995 required the use of deposit control additives to minimize the formation of fuel injector and intake valve deposits. Both California and the EPA required that additives be certified in specified test fuels in vehicle tests. The fuel injector test procedure is ASTM D5598, Test Method for Evaluating Unleaded Automotive Spark-Ignition Engine Fuel for Electronic Port Fuel Injector Fouling, and the intake valve deposit test procedure is ASTM D5500, Test Method for Vehicle Evaluation of Unleaded Automotive Spark-Ignition Engine Fuel for Intake Valve Deposit Formation. ASTM developed more recent, nonvehicle versions of these tests for consideration by the EPA. These are ASTM D6201, Test Method for Dynamometer Evaluation of Unleaded Spark-Ignition Engine Fuel for Intake Valve Deposit Formation, and ASTM D6421, Test Method for Evaluating Automotive Spark-Ignition Engine Fuel for Electronic Port Fuel Injector Fouling by Bench Procedure.

GASOLINE-OXYGENATE BLENDSBlends of gasoline with oxygenates are common in the U.S. marketplace and, in fact, are required in certain areas, as discussed previously. These blends consist primarily of gasoline with substantial amounts of oxygenates, which are oxygencontaining, ashless, organic compounds such as alcohols and ethers. The most common oxygenate in the United States is ethanol. MTBE was widely used but has been phased out in many states because of concern over ground water pollution. It is still used in some European countries as an octane trimming agent. Other ethers, such as ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and diisopropyl ether (DIPE), are receiving some attention, but have not yet achieved widespread use. Like MTBE, these ethers also are banned in some states. Methanol/tert-butyl alcohol mixtures were blended with gasoline on a very limited scale in the early 1980s but cannot be used now until they have a supplemental toxics registration. When methanol was used as a blending component, it had to be accompanied by a cosolvent (a higher-molecular-weight alcohol) to help prevent phase separation of the methanol and gasoline in the presence of trace amounts of water. EPA waiver provisions also required corrosion inhibitors in gasoline-methanol blends. ASTM D4806, Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as Automotive SparkIgnition Engine Fuel, describes a fuel-grade ethanol that is suitable for blending with gasoline. ASTM D5983, Specification for Methyl Tertiary-Butyl Ether (MTBE) for Downstream Blending with Automotive Spark-Ignition Fuel, provides limits for blending MTBE in gasoline.

Renewable Fuel StandardIn 2007, the EPA finalized regulations for the RFS, which was authorized by the Energy Policy Act of 2005. The RFS establishes a minimum requirement for the volume of renewable fuels blended into automotive spark-ignition and diesel fuels. The national minimum volume requirement started at 4.0 billion gallons per year of renewable fuel in 2006 and increases to 7.5 billion gallons per year in 2012. Each producer and importer of fuel in the United States is obligated to demonstrate compliance with this requirement based on the pro rata share of fuel it produces or imports. With the passage of

Sampling of Gasoline-Oxygenate BlendsSampling of blends can be conducted according to the procedures discussed earlier; however, water displacement must not be used, because of potential problems associated with the interaction of water with oxygenates contained in some spark-ignition engine fuels.


CHAPTER 2

n


13

Test Methods for Gasoline-Oxygenate BlendsSome of the test methods originally developed for gasoline can be used for gasoline-oxygenate blends, while certain other test methods for gasoline are not suitable for blends. To avoid the necessity of determining in advance whether a fuel contains oxygenates, ASTM D4814 now specifies test methods that can be used for both gasolines and gasolineoxygenate blends. This has been made possible by experience with some test methods, modification of existing test methods, and the development of new ones. Gasolineethanol blends are not included in the scopes of many test methods, and the precision statements do not apply. ASTM is working to modify the scopes and develop precision statements for the test methods specified in ASTM D4814 to cover gasoline-ethanol blends. Additional test methods and limits need to be developed to protect against incompatibility with elastomers and plastics, corrosion of metals, and other factors that may affect vehicle performance and durability. In general, the test methods discussed previously for determining distillation temperatures, lead content, sulfur content, copper corrosion, solvent-washed gum, and oxidation stability can be used for both gasolines and gasoline-oxygenate blends. In some cases, standard solutions with which to calibrate the instrument must be prepared in the same type of fuel blend as the sample to be analyzed. Some of the test methods for vapor pressure and vapor/ liquid ratio are sensitive to the presence of oxygenates in the fuel, and approved procedures were discussed earlier in this chapter.

two distinct phases is the criterion for failure. The test method originally developed to measure the water tolerance of ethanol blends was determined in an interlaboratory study to not be sufficiently accurate and was withdrawn. The limits were removed from the specification section of ASTM D4814 and placed in Appendix X8 for reference. The need for a water tolerance test is still thought to be important, and a water tolerance specification would be included in ASTM D4814 if a suitable test can be developed.

Compatibility with Plastics and ElastomersPlastics and elastomers used in current automotive fuel systems such as gaskets, O-rings, diaphragms, filters, seals, etc., may be affected in time by exposure to motor fuels. These effects include dimensional changes, embrittlement, softening, delamination, increase in permeability, loss of plasticizers, and disintegration. Certain gasoline-oxygenate blends can aggravate these effects. The effects depend on the type and amount of the oxygenates in the blend, the aromatics content of the gasoline, the generic polymer and specific composition of the elastomeric compound, the temperature and duration of contact, and whether the exposure is to liquid or vapor. Currently, there are no generally accepted tests that correlate with field experience to allow estimates of tolerance of specific plastics or elastomers to oxygenates.

Metal CorrosionCorrosion of metals on prolonged contact with gasolines alone can be a problem, but it is generally more severe with gasolinealcohol blends. When gasoline-alcohol blends are contacted by water, the aqueous phase that separates is particularly aggressive in its attack on fuel system metals. The tern (lead-tin alloy) coating on fuel tanks and aluminum, magnesium, and zinc castings and steel components such as fuel senders, fuel lines, pump housings, and injectors are susceptible. A number of test procedures, other than long-term vehicle tests, have been used or proposed to evaluate the corrosive effects of fuels on metals. The tests range from static soaking of metal coupons to operation of a complete automotive fuel system. None of these tests has yet achieved the status of an ASTM standard. Applicable ASTM SpecificationsASTM D4806 Title Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel Specification for Automotive Spark-Ignition Engine Fuel Specification for Fuel Methanol (M70-M85) for Automotive Spark-Ignition Engines Specification for Fuel Ethanol (Ed75-Ed85) for Automotive Spark-Ignition Engines Specification for Methyl Tertiary-Butyl Eth

Date post:	02-Dec-2014
Category:	Documents
Upload:	fernandoper
View:	920 times
Download:	5 times

Signicance of Test for Petroleum AST

Documents