Limited Area Sprinkler Systems in closets and crawl spaces are a good ideal but is anyone testing to make sure they work ?

 Limited area Sprinklers are a great idea I recently came across one in an apartment building  tenant storage room 

Its just 3 sprinkler heads run off the buildings main water line  NFPA 13 limits these systems to 6 heads and they make sense where you don't need a full sprinkler system but want extra protection. Like storage rooms and Trash chutes etc 

 

But the question is who or when are these to be tested if there ever tested ? 

I can find nothing in codes require them to be tested other than NFPA25. to make matters worse   valves serving them are not locked or electrically monitored  like regular sprinklers . Seems to be a AHJ call and the bigger problem is really old limited systems generally have no inspectors test valve or flow switch with bell which limits there inspection. 

So the next question is after they have been installed 20 to 30 years will they even still work? 

I have seen steel pipe sprinklers where rust was so bad heads did not activate  should not happened with a copper or plastic piping but still who is keeping an eye on them? 

Lots of questions no answers .