What is the correspondence between the Chinese national standard B1 fire resistance rating and international standards (such as ASTM E84 or BS 476)?

The Chinese national standard B1 (GB 8624) classifies materials as flame-retardant. In the North American ASTM E84 test, a flame spread index (FSI) ≤25 and a smoke index (SDI) ≤450 constitute Class A (the highest level), and high-quality flame-retardant polyester fiberboard can reach this level. The British BS 476 Part 7 corresponds to Class 1. If the customer has specific export requirements, please inform us of the target country when requesting a quote, and we can adjust the flame-retardant formula for testing according to specific standards.