ASTM’s Subcommittee D02.A Maintains Spark-Ignition Engine Fuel Quality

by Ben Bonazza and Lew Gibbs

One standard can be a big responsibility, especially when it specifies a product that is environmentally sensitive, is used by millions in the United States, and is heavily regulated. Subcommittee D02.A works throughout the year to maintain not only this standard on spark ignition engine fuel (that is, the gas in your car), but many others as well.

Subcommittee D02.A on Gasoline and Oxygenated Fuels has the primary task of developing and maintaining specifications to insure the quality of gasoline sold in the United States. More recently, the subcommittee has broadened this task to include the development of specifications for oxygenates (the gasoline blending components which are added to make today’s cleaner-burning, reformulated gasolines), and for alcohol fuels, which contain predominately ethanol and methanol.

Today, the work of the subcommittee is changing, requiring harmonization with the efforts of regulatory agencies, such as the U.S. Environmental Protection Agency and the California Air Resources Board. This harmonization is required during the development of standards and also in determining the appropriate use of standards in writing regulations.

Who We Are

Subcommittee D02.A is a group of diverse, mainly technical, individuals whose primary interest is the quality of automotive fuels for ground-based spark-ignition engines. We have 139 voting members and 109 non-voting members for a total membership of 248. The voting membership breakdown is as follows:

• 63 producers (45%),
• 67 general interest (48%),
• Eight users (6%), and
• One consumer (<1%).

Producers are mainly represented by the integrated petroleum companies, ethanol producers, and pipeline companies, whereas the users are represented by the auto manufacturers and their suppliers. The general interest members include state and federal regulators, independent laboratories, and consultants. Although the subcommittee is in balance according to ASTM regulations (producers < general interest + users + consumers), it is obvious that it contains a disproportionately large number of producers relative to users. Our automotive members expressed considerable concern over this voting imbalance, and ASTM’s Committee on Standards expressed similar concern. This forced the subcommittee into action and a balanced voting system (BVS) was developed, with ASTM’s approval. The BVS gave each voting bloc an equal vote. The new voting system is compared with the standard ASTM voting system in Figure 1. The imbalance issue resulted in the departure of all but one of our automotive representatives (Honda) in 1997, just six months before the new voting system was approved and put into effect (Figure 2). The lack of sufficient user representation often makes it difficult to address the user position in building consensus standards.

What We Do

As is clearly defined in our scope, the duties of the subcommittee include 1) developing specifications, 2) developing test procedures, and 3) developing information on spark-ignition engine fuels. Figure 3 lists items in each of these categories under the jurisdiction of Subcommittee D02.A. Of these, unquestionably the most important and the one the subcommittee spends the most time on is the U.S. gasoline specification, D 4814, Specification for Automotive Spark-Ignition Engine Fuel. This specification is used by refiners, gasoline marketers, state and federal government agencies, shippers, and pipeline operators to specify product properties for exchange and sale. Further, many foreign gasoline specifications are based on D 4814. The specification describes important performance characteristics of automotive fuels, such as volatility, lead content, copper corrosion, solvent-washed gum, sulfur content, oxidation stability, water tolerance, and driveability index. Although D 4814 covers gasoline blends with oxygenates, such as alcohols and ethers, it does not cover fuels that contain an oxygenate as the primary component. These “alternative” fuels, fuel methanol (M85) and fuel ethanol (E_d85), are covered by their respective specifications, D 5797 and D 5798. The subcommittee also has developed and maintains specifications for the oxygenates commonly added to gasoline, ethanol (D 4806) and methyl tert-butyl ether (MTBE, D 5983).

Subcommittee D02.A’s test methods, also shown in Figure 3, include tests developed to measure intake valve deposits (IVD) and port fuel injector (PFI) deposits, commonly formed in spark-ignition engines. Recently, newer replacement IVD and PFI test methods have been developed (D 6201 and D 6421). The water tolerance test (D 6422) was developed to measure the ability of a fuel to dissolve water without phase separation, a property that is critical for gasoline-alcohol blends. Finally, D 6423 was developed at the request of General Motors to detect highly acidic ethanol in the field. Acidic ethanol can cause corrosion of fuel system components.

Along with specifications and test methods, Subcommittee D02.A also develops information to educate people in the area of fuels. Many of our specifications provide educational information. D 4814 provides a wealth of information in its appendices, including EPA rules relating to fuel volatility, lead and phosphorous contents, deposit control additive certification, and use of oxygenates in blends with unleaded gasoline.

However, Subcommittee D02.A has one document developed strictly for educational purposes. This is Research Report D02-1347, Research Report on Reformulated Spark-Ignition Engine Fuel (see Figure 3 and the article on this subject). This document is designed to provide comprehensive and detailed information on federal and state requirements for reformulated gasoline to be used in ground vehicles equipped with spark-ignition engines. The most valuable aspect of this document is that the subcommittee’s Reformulated Gasoline Task Force constantly updates it, so the information is always current.

How We Are Organized

Subcommittee D02.A is organized into four sections, a Balanced Technical Advisory Panel (BTAP) and a number of task groups, as shown in Figure 4. The Specifications and Volatility Sections, with their task groups, carry out the majority of the subcommittee’s work. The Specifications Section, as the name indicates, keeps the subcommittee’s many specifications current, and addresses new concerns that come to light relative to them. Because volatility is such an important gasoline property, we have a separate section, the Volatility Section, to deal with these issues.

The BTAP was established during the development of the balanced voting system process. It is a special panel that reviews data on highly contentious issues and evaluates the idea’s technical merit. Based on its evaluation, the BTAP will either recommend that the subcommittee adopt a proposal or it will recommend that the supporters of the proposal develop additional and more convincing data before bringing the issue before the subcommittee. The BTAP’s recommendation is not binding, and any proposal may be brought directly to the subcommittee without BTAP’s approval.

Our Work with Regulatory Agencies

Before the federal government began controlling maximum vapor pressure in 1989 under its Phase I program, there was little federal influence on Specification D 4814. As a result of the Clean Air Act Amendments of 1990, there have been major adjustments to D 4814. Figure 5 shows what properties are under the influence of federal regulations and which are still the prerogatives of ASTM. D 4814 has incorporated all of the federal vapor pressure regulations, which are only in effect in summer, in eight new tables. In winter, the limits revert back to the original specification D 4814 limits. An appendix discusses all of the other federal limits. As mentioned earlier, Subcommittee D02.A’s research report on reformulated gasoline provides comprehensive and detailed information on federal and state requirements of reformulated gasoline for ground vehicles equipped with spark-ignition engines. Maintaining these documents requires close cooperation with the regulatory agencies.

When the California Air Resources Board staff held workshops to develop the California Phase 3 reformulated gasoline program, Subcommittee D02.A representatives participated in the development of the state’s specification for ethanol. The state uses specification D 4806 as an integral part of their specification. The state of California’s additional property requirements are shown in an appendix of specification D 4806 along with future federal requirements. The introduction of these additional property limits into D 4806 will be considered in the future when the regulations become effective.

Intake valve deposit test method D 5500 and port fuel injector deposit test method D 5598 are specified as part of the federal and state of California gasoline deposit control additive certification processes. Subsequently, Subcommittee D02.A, in conjunction with the Coordinating Research Council (CRC—an independent organization that directs studies on the interaction of automotive equipment and petroleum products), has developed new replacement procedures, Test Methods D 6201 and D 6421. Subcommittee D02.A is working with other stakeholders (the Alliance of Automobile Manufacturers, the American Chemistry Council, and the American Petroleum Institute) to develop a proposal. It will be for the adoption by the Environmental Protection Agency of the new engine deposit test methods and the acceptance of the latest versions of the original deposit test methods.

Our Recent Accomplishments

The standard specifications and test methods of Subcommittee D02.A are living documents. The goal to keep specification D 4814 current with federal specifications requires considerable attention and balloting of revisions. Table 1 summarizes the chronological changes made to D 4814 since 1995. Every year some change has been made in response to federal regulation changes. Changes were also made to ensure better performance of gasoline. The most important of these occurred in 1998 when a driveability index (DI) system was incorporated in D 4814, which ensured for each volatility class good cold-start and warm-up performance of gasoline-powered vehicles. Currently under ballot is the addition of a second DI limit at the point of sale.

Similarly, changes were made to specification D 4806 to keep it current. An important recent change as mentioned earlier was the development of test method D 6423 and the addition of a limit to control the acid strength of ethanol used in blends with gasoline to protect fuel system components. The same action was taken for specification D 5798.

Changes have been made as necessary to the various test methods developed by Subcommittee D02.A to keep them viable.

Our Current Activities

Subcommittee D02.A has a number of projects currently under way to maintain and improve its specifications and test methods. To better control the properties of products, new and improved test methods are required. Subcommittee D02.A works closely with the various Committee D02 property subcommittees. Current needs are for test methods to determine low levels of volatile silicon compounds, very low levels of lead, particulate contamination and improved test methods for determining stability. The subcommittee also participates in interlaboratory studies to help develop precision statements for test methods. Currently in progress is an interlaboratory study to determine the precision of test method D 6422. Subcommittee D02.A also works with outside organizations, such as the CRC. Current projects with the CRC involve determining the impact of blending ethanol on DI and driveability and on hot-fuel-handling performance in modern fuel-injected vehicles.

Subcommittee D02.A consists of members with diverse interests. It is an active group with many specifications and test methods to develop and maintain relating to fuels used in ground vehicles powered by spark-ignition engines. Many of the fuel properties are now controlled by federal and state emissions regulations. This complicates the group’s responsibility to provide high-performing fuels, but Subcommittee D02.A is up to this task. //

Copyright 2002, ASTM