New addition to the stacks

I must disclaim up front that I know this was a necessary safety feature that we needed in our stacks. I realize there is probably no way to make a retrofitted sprinkler system attractive in an old building.
When I pass these in the stacks, I can't help but wonder what our patrons will think about the new additions...our stacks don't have a particularly warm and fuzzy reputation to begin with.
However, I am totally fascinated by the little hanging signs that say "Main Drain" and "Inspectors Test". Very curious...