The following in-use testing requirements are an extension of the verification process and each retrofit manufacturer has a responsibility to fulfill them. There are two phases to the in-use testing program. In each phase units in normal field operation must have reached a certain age prior to being tested. In-use testing is not required to begin until 500 units have been sold. Technology manufacturers will inform EPA, as part of their verification application, when they believe they will have sold 500 units.
All testing is the responsibility of the retrofit technology manufacturer.
The actual test method to be used will depend upon the retrofit product. One must be able to compare the test results directly. After-treatment units that have reached the required age in the field are to be tested for continued efficacy in one of two ways. The units may be tested by the manufacturer using a system such as an engine dynamometer, chassis dynamometer or a mobile emissions detection system for tests with the device installed and then tests with the device removed. Control Strategy Upgrade Kits - Replacement of mechanical fuel control with electronic fuel control is an example of a control strategy upgrade kit.