EPA adopts unified engine testing requirements.

The U.S. Environmental Protection Agency (EPA) announced that it has revised engine test procedures to reflect what the agency called "current state-of-the-art portable emission measurement technology." EPA said the rule also creates unified testing requirements for all engines that it said

While moving closer to unified testing as emissions standards tightened, historically, individual engine or vehicle markets have had their own set of testing procedures, though with many similarities in test procedures across the various sectors.

"As we introduced new regulations for individual sectors, the more recent regulations featured test procedure updates and improvements that the other sectors did not have," EPA said in making the announcement. "As this process continued, we recognized that a single set of test procedures would allow for improvements to occur simultaneously across engine and vehicle sectors. In addition, a single set of test procedures is easier to understand, and it is easier to move toward international test procedure harmonization if we specify only one set of test procedures."

As part of all this, EPA has grouped all its engine-dynamometer and field-testing procedures into one: "Part 1065: Engine-Testing Procedures."

"Part 1065 is advantageous for in-use testing because it specifies the same procedures for all common parts of laboratory and field testing," EPA said. "It contains new provisions to help ensure that an engine's operation in the laboratory is much like in-use operation in the field. These new provisions will ensure that laboratory testing and field testing are conducted consistently."

In addition to reorganizing and rewriting the test procedures for improved clarity, EPA is making a variety of changes that it said will improve the content of the testing specifications.

These include: writing specifications and calculations in international units; adding procedures by which manufacturers can demonstrate that alternate test procedures are equivalent to specified procedures; including specifications for new measurement technology that has been shown to be equivalent or more accurate than existing technology; adopting procedures that improve test repeatability and calculations that simplify determination of emission mass; specifying new procedures for testing engines in the field; defining calibration and accuracy specifications that are scaled to the applicable standard, which allows the agency to adopt a single specification that applies to a wide range of engine sizes and applications; and using a more comprehensive set of definitions, references and symbols.

EPA added that some emission-control programs already rely on the test procedures in part 1065, including those for land-based non-road diesel engines, recreational vehicles, and non-road spark-ignition engines over 19 kW. EPA added it is also adopting the lab-testing and field-testing specifications in part 1065 for all heavy-duty highway engines.

"In the future, we plan to apply the test procedures specified in part 1065 to other types of engines, so we encourage companies involved in producing or testing other engines to stay informed of developments related to these test procedures," EPA said.

For heavy-duty highway engines, the procedures in part 1065 replace those currently published in 40 CFR part 86, subpart N. EPA said it is scheduling a gradual transition from the part 86 procedures and will allow the use of part 1065 procedures as an option through the 2009 model year. Starting in the 2010 model year, part 1065 procedures will be required for any new testing.

For all testing completed for 2009 and earlier model years, EPA said manufacturers may continue to rely on carryover test data based on part 86 procedures to certify engine families in later years. In addition, other subparts in part 86, as well as regulations for many different non-road engines refer to the test procedures in part 86.

The main differences between PEMS and laboratory systems are that, with PEMS, emissions are sampled from the raw undiluted exhaust, and engine power is calculated using signals from the engine computer rather than being measured using a laboratory dynamometer.

EPA said it is also adopting a requirement that manufacturers of heavy-duty highway engines use ramped-modal testing to show that they meet steady-state emission standards using the Supplemental Emissions Test (SET). Much like the part 1065 procedures, the ramped-modal testing is optional through 2009 and becomes mandatory in the 2010 model year. The conventional approach for steady-state testing is to measure emissions separately for each mode. Ramped-modal testing involves a single, continuous emission measurement as the engine operates over the test modes in a defined sequence, including short transition segments between modes. Ramped-modal testing offers several advantages, according to EPA, including increased accuracy for measuring very low levels of particulate matter emissions and substantially reduced testing time.

http://www.epa.gov/otaq/hdhwy.htm#tech