Basic testing program
The basic testing program to achieve UL Recognition involves three identification tests: Infrared Spectroscopy (IR), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Additionally, plastics may be subjected to small scale flammability tests as well as a variety of ignition, mechanical, electrical, and short term thermal tests for application in other UL Recognized Components and UL Listed end products. Once the identification, flame tests, and short term physical tests are successfully completed, a unique grade designation and the respective ratings/classifications for the product is published on the ULiQ for Plastics database.
UL Field Representatives conduct quarterly follow-up visits to each manufacturing location. Representative production samples of the UL Recognized Plastic is picked up annually and sent to UL for comparison to the original IR, TGA and DSC reference graphs available on file at UL. If the plastic material also has a UL 94 vertical flame rating (like V-0, V-2, V-1 etc), samples are also subjected to the same flammability tests.
Successful comparison to the archived reference IR, TGA and DSC is an indication that there is continuity in the product's formulation. Successful correlation of the flame class between the samples selected during Follow-up Services Inspection and the initial published rating are also required to maintain UL Recognition for the product. Should any of the above tests not comply, action is taken to withdraw the Recognition or downgrade the plastic. A downgrade includes a mandatory name change as an indication of a degraded characteristic variation.
The continued publication of a specific material (with a specific designation or name) enables the continued use of that plastic material in end-use products, with assurance that the original characteristics are maintained. Besides the obvious safety aspects of using a Recognized plastic material, end - product users (of the Recognized plastic) are subject to a reduced test program of their product, and similar advances apply to the use of UL Recognized switches, Appliance Wire, terminal blocks and others.