Safety Knights

OSHA says 30 mins: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.252

But I think NFPA is longer - 3 hours maybe?

OSHA says 30 minutes. NFPA 51B says 1 hour.

Drew is correct on OSHA and he would know about NFPA.

I am asked by my customers if they should use OSHA numbers, like for PELs, TVAs, and other specifications like this one, when compared to CDC, NIOSH, ACGIH, NFPA, NEC, and ANSI.

I reply, "In the vast majority of instances OSHA is the bare MINIMUM. The others are usually much more current and designed by experts in their fields. OSHA specs were sometimes written with political and lobbying input. If that is not enough for you, many of the OSHA regs were written when I was in early high school taking Driver's Ed and just noticed girls. I took Driver's Ed with Fred Flintstone!" (Now to think about it, Barney and he were on Network TV at that time too).
I add, "OSHA might be adequate, but the others are SAFER, which do think you want to do? If your asking me as your consultant go with the SAFER! SAFETY is never adequate!" My $.02

PS I remember being a Personnel Manager in 1987, over the Christmas Holiday during a Maintenance Shutdown. Literally I was completing writing a new policy on the NEW upcoming OSHA Haz Com policy in my office with no one around. The guard brings into my office a man in a rather plain suit and tie. He introduces himself and pulls out a badge. He is a CHSO from MiOSHA (Michigan). He says he is there for a general audit as it has been awhile. I explain, except for Maintenance and Clean-Up Crews no one is in the plant and ask if he wants to wait. He declines and says he wants to go out in the plant anyways. It was a short tour so I ask him some questions on the new Haz Com Standard. I remember him telling me Table Z-1 in 1910.1000 would be updated every few years. To my knowledge it has not changed in 35 years!