Overview of Testing Requirements. The data of primary interest in this verification testing are the reduction in emissions of NOx, HC, PM, and CO. Emissions reductions are defined as the percentage reduction obtained between a base case and the SCR candidate case. For all engine and vehicle types, emissions measurements are made using the FTP certification test cycle applicable to the engine or vehicle for which the SCR is intended and the SET test cycle for highway engines. The details of the tests are different for different engines and vehicles and are given below. A single test of an engine without a control system installed, followed by one with the system installed, is not considered to be adequate for all SCR ETVs. Emissions from engines or vehicles may increase if changes in the product performance occur as the SCR system ages. These characteristics require that the ETV for SCRs be designed to provide emissions reductions over the projected life of the system. Testing conducted under this protocol utilizes individual FTP and special tests that measure emission rates of various pollutants. Replicate tests are conducted at a particular test point in the service life, defined in either hours or miles, of an engine or vehicle. The FTP and special tests are combined to give a combined emissions rate for each pollutant. The complete ETV test includes a minimum of two test points over the projected service life, each of which gives a combined tests emissions rate for either the base or the candidate SCR. The combined emissions rates are then used to estimate the emissions reduction for each pollutant. The decision to assign a single engine emissions reduction to a technology for the OTAQ verified technology list is made by OTAQ based on the ETV verification.
