When one is looking at putting a fire alarm in a ‘spec’ (speculative/generic/‘flex’) industrial building or space (why? NFPA 101 requires fire alarms at an occupancy threshold of only 100 folks, and even in single story buildings, vs. the 500 folks on a level other than the level of exit discharge required to trigger the IBC fire alarm requirements for F-1, making it very easy to wind up with a big enough space to trigger the requirement in a jurisdiction that adopts NFPA 101), how the heck is one supposed to design a workable/economical audible notification system for that space?
One can’t skip audibles altogether by NFPA 72 rules alone until one hits 95dBA ambient, so one would presume audible notification is required, but the 88dBA ambient figure given by A.18.4.4 for industrial occupancies in the 2019 and newer editions of NFPA 72 renders audible notification economically impractical when using the 15dBA over ambient criterion, even when using beefy sounders (such as the Pfannenberg PATROL PA 20s, that can easily exceed 110dBA at 1m distance and even exceed that mark at 3m in some cases).
Does one presume 5dBA over some assumed sustained-peak sound level in these cases, with a corresponding dBA limit on noise from individual machines? Or does one presume that audible notification would need to take place at reduced (private mode) volumes, or not at all given the presence of strobe coverage in the space? Does one just leave it to the tenant finish to supply appropriate notification given the equipment they’re installing, or use a reduced ambient level in the 80-83dBA range as that’s the most one can get a practical design for?