In our audio booth (telephone booth sized closet) over the past few years we have used Auralex acoustic foam purchased from Musician's Friend. However the town fire inspector in her annual visit told us this has to go - fire hazard. She quoted the Power Station fire, which was certainly bad news considering they used non-acoustic foam that burned hot and fast.
I looked up the burn test report from the Auralex website, and lo and behold, while the foam is self extinguishing, this is after flames reach up to 20 feet. 20 foot flames for half a second can still burn your office down.
What do others use in an audio booth and how do you get approved by the fire marshall?
For a better look over foam and less cost. You can build your own baffles using Owens Corning 703. They are compressed fiber glass panels. Wrap them in Gilford of Maine fabric. Not sure of fire rating, but our ISO booth did pass our fire inspection. Good luck.