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National Clean Diesel Campaign (NCDC)

Working Together for Cleaner Air


The Verification Program evaluates the emission reduction performance and durability of specific retrofit technologies when submitted by manufacturers. The verification process includes a thorough technical review and tightly controlled testing to quantify levels of emission reductions and identify engine operating criteria and conditions that must be met for technologies to achieve those reductions.

Verification Process:

  1. Apply for Verification: This is a two-step verification process. To begin the verification process, manufacturers must first complete a Part 1 of the application (PDF) (5 pp, 567K, EPA-420-F-12-023, May 2012) and submit it to Tech_Center@epa.gov :

    Part 1 will be used by EPA as an initial review of the verification request. EPA will review the application and follow up with a Part 2, requesting technology-specific information for further review. The application forms outline the information required for verifying a technology. For evaluation of the technology, EPA requires a clear explanation and documentation of:

    • How the technology works
    • Basis for emission reduction claims
    • Intended market application and engine groups
    • Potential unique testing needs
    • Operating criteria, including any operating constraints (e.g., ambient air temperature or conditions, backpressures, etc.)
    • Potential concerns for health or safety
    • How and where the technology is installed on the vehicle
    • Experience with in-use operation of the specific technology and similar designs
    • Previous testing

    Considerations before applying for verification:

    • Manufacturer Representative: The applicant for verification must be a manufacturer representative with detailed knowledge of the technology, its manufacture, in-use operation, performance, durability and prior testing. The manufacturer representative is responsible for attesting to EPA that information is correct and that the technology will be manufactured, installed and perform as described.
    • Regulatory Requirements: Some technologies may not qualify for verification as the product may have regulatory requirements that supersede verification. For example, manufacturers must apply and certify engine conversion for alternative fuels, consequently these engines could not use the verification process
    • Availability: The retrofit equipment submitted for verification must be commercially available for installation. No products still in the research and development stage will be verified.
    • Health Effects and Safety: Concerns with health effects or safety may need to be addressed prior to EPA review of a technology for verification
    • Intended Market and In-use Experience: Manufacturers should identify specific engine and vehicle types for the intended market segment, and provide documentation from in-use experience. EPA has grouped together engine families with similar emissions performance characteristics for verification purposes. The retrofit manufacturer may provide test data showing that a product tested on one engine family may be applied to other similar engine families. For more information, view Highway Engine Family Groups (PDF) (2 pp, 76K, May 2006) or Non-road Engine Family Groups (PDF) (4 pp, 184K, May 2006).
  2. Application Acceptance: Once the manufacturer has submitted the two-part application and addressed the follow-up questions described above, the application will be accepted.
  3. Develop a Test Plan: A test plan based on the specific technology and manufacturer's intended market will be developed with input from EPA and the manufacturer.
  4. Testing: Prior to testing, the manufacturer will provide a de-greened device (25-125 hrs of operation), an aged device (1000 hrs of operation), and possibly a test engine to the test facility. EPA prefers the devices be aged in normal in-use operation on vehicles representative of the intended verification market. EPA must approve the method of testing for verification.
  5. Data Analysis and Interpretation: Once testing is complete, EPA will review the data to determine if the technology qualifies for verification and assign the level of emission reductions.
  6. Notice of Verification Letter: Upon verification of the technology, the manufacturer will receive a Verification Letter. Sample Verification Letter (PDF) (2 pp, 564K, August 2010)
  7. Verified Technologies List: Once the technology has been verified, EPA will add it to the Verified Technologies List. The list describes the technology and other information contained in the Verification Letter so that potential customers may determine if they wish to purchase the technology.
  8. Verified Technologies and Changes: Products sold as verified technologies must be produced and installed as described to EPA. If a manufacturer changes a verified technology or implements changes relative to information provided to EPA, the manufacturer must update the documentation with the Verification Program. If EPA determines the changes may impact performance or the changed technology may not be represented by the original verification, EPA may require further testing or conclude the changed product requires a separate verification.
  9. In-Use Emissions Testing: To remain on EPA’s Verified Technology List, the manufacturer must comply with EPA's In-Use Emissions Testing Requirements. Once the technology is placed on the verified technology list and 500 units are sold, the manufacturer is responsible for conducting in-use testing on field-aged devices and reporting the results to EPA. Prior to retrieving devices, EPA will work with the manufacturer to select the appropriate sources of devices and establish test sequences.

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