What is the maximum char length for newly introduced mattresses tested in accordance with 16 CFR 1632, "Standard for the Flammability of Mattresses…

The U.S. Consumer Product Safety Commission (CPSC) standard 16 CFR 1632, "Standard for the Flammability of Mattresses and Mattress Pads," is a test designed to measure the ignition resistance of a mattress when exposed to a smoldering cigarette. The primary acceptance criterion for this test is based on the char length produced on the mattress surface. According to the standard, for a mattress to pass the test, the char length must not extend more than 2 inches (51 mm) in any direction from the nearest point of the test cigarette.

B. 3 in. (72 mm): This exceeds the maximum allowable char length. A measurement of 3 inches would constitute a test failure.

C. 4 in. (102 mm): This value is double the permitted maximum and would be a clear failure of the cigarette ignition resistance test.

D. 5 in. (127 mm): This significantly exceeds the 2-inch limit specified in 16 CFR 1632, indicating a failure of the test.

1. U.S. Consumer Product Safety Commission, 16 C.F.R. § 1632.4(d), "Test procedure," Acceptance criterion. The regulation states: "The char length on the mattress surface shall not be more than 2 inches (5.1 cm) in any direction from the nearest point of the cigarette."

2. NFPA 921, Guide for Fire and Explosion Investigations, 2021 Edition, Section 6.4.5.1.1. This section discusses the CPSC standard and notes: "The test criterion is that the char length is not to exceed 2 in. (51 mm) in any direction from the cigarette."

3. Ohlemiller, T. J., & Gann, R. G. (2004). Development of a New Flammability Test for Mattresses (NIST Technical Note 1477). National Institute of Standards and Technology. Page 5. In its description of the existing standard, the document states: "The pass/fail criterion for this test is that the char length on the mattress surface does not extend more than 50 mm (2 in) in any direction from the cigarette." (Available via NIST public repositories).