I have railed against these refrigerants and all the code/standard revisions to make them easier to use. Now, OSHA has adopted the 7th edition of the GHS, and we now have Cat 1A and 1B. These flammable refrigerants fall in the 1B’s because:
1) they have an LEL above 6%, and
2) they burn at a rate less than 10 cm/sec
Never before have we classified flammables based on the flame propagation rates, but we do now.
When you watch the video, see if 10 cm/sec is slow!?!?