Emission Screening Test for Marine Outboard Engines

The United States Environmental Protection Agency’s (U.S. EPA’s) National Vehicle and Fuel Emissions Laboratory (NVFEL) has been developing new approaches for use in screening emissions from various types of new and in-use (used) engines to investigate if their exhaust emissions comply with federal emission standards. If the results from screening tests suggest anything unusual, EPA’s compliance program could investigate further to determine if that particular engine group or family should receive more rigorous compliance testing and analysis. In 2019, the EPA finished developing a means to screen the emissions of marine outboard engines, including the use of specialized equipment, laboratory methods, and procedures capable of controlling outboard marine engines to screen whether their exhaust is in line with appropriate emission standards. This paper describes the purpose of the new screening tests and the test articles, which can be tested, as well as the design of the test cell equipment, their capabilities, and the specific test procedures used to screen the emissions from outboard engines. An evaluation of both raw and dilute engine exhaust sampling methods used to study the emissions is presented, along with the results and analysis of the initial screening tests on two four-stroke gasoline outboard engines. The test results from the two engines reveal that the new testing capability is quite suitable to test and screen emissions from different sizes and makes of marine outboard engines.