The UL Listing process
For customers who have not experienced a UL hydrogen product investigation, it is often easier to divide the evaluation into two segments, the first being a preliminary investigation and the second a listing investigation. This project division allows the manufacturer to respond to the recommendations of the preliminary investigation prior to the start of the listing investigation. However, for minor changes to a currently Listed product or for work that is particularly straightforward, a preliminary investigation may not be necessary. The preliminary investigation tasks outlined below can be completed as part of a listing investigation.
Preliminary investigation
A preliminary investigation is initiated by submitting the information outlined below along with a written request to begin the work. Application forms will be furnished to begin the project. A UL engineer will either visit the manufacturing facility or conduct an in-house review to examine a prototype or production sample that closely reflects the product to be tested and ultimately UL Listed. The sample need not be functional but should contain the key operational components. The sample will be reviewed to determine if the construction complies with the current requirements. This review results in a preliminary investigation report indicating any portions of the construction that are not in compliance. Additionally, it may specify which options for compliance may be considered and list any additional information necessary to initiate a listing investigation. The report will also outline the proposed test program and provide a cost estimate for the listing investigation.
Listing investigation
The listing investigation will take place upon completion of the preliminary investigation and once all necessary product changes are in place. The listing investigation can be initiated when a written request to begin the work is submitted along with any information outlined in the preliminary investigation letter report. An agreement form and a request for payment form will then be sent. Next, a final construction evaluation and test sequence will be conducted at UL and/or the manufacturing facility. Then, the UL report documenting the construction of the product will be prepared. Finally, a local UL field representative will conduct an initial product inspection (IPI) to verify that the product's construction is in accordance with the UL report. After this IPI has been successfully conducted, the manufacturer is authorized to apply the UL Mark to the product.
Product information
Applications to initiate the investigation will be furnished upon receipt of the following information (where such information is applicable to the product being submitted). See the sample and information requirements page for more detailed information.
- Components
- Control panel
- Exhaust system
- Fault analysis
- Fuel or fluid handling system
- Gasket material
- Insulation systems
- Manufacturer data
- Markings
- Optional and alternate constructions
- Peripherals
- Photographs
- Plastics
- Printed wiring boards
- Product designation system
- Product information and instructions
- Ratings
- System diagrams
If some of the above information is not available at the time of submittal, it may be possible to proceed with the project. However, there may be delays in the evaluation of those tasks related to the missing materials or information.
