16 C.F.R. § 1616.3 – General requirements.

(a) Summary of test method. Conditioned specimens are suspended one at a time vertically in holders in a prescribed cabinet and subjected to a standard flame along their bottom edges for a specified time under controlled conditions. The char lengths are recorded.
(b) Test criteria. The test criteria when the testing is done in accordance with § 1616.4 Sampling and acceptance procedures and § 1616.5 Test procedures are:
1. (1) Average char length. The average char length of five specimens shall not exceed 17.8 cm. (7.0 in.).
2. (2) Full-specimen burn. No individual specimen shall have a char length of 25.4±0.5 cm. (10±0.2 in.).
(c) Details of the number of specimens which must meet the above test criteria for unit acceptance is specified in § 1616.4.