A new warehouse with a huge refrigerated storage department (1350 sprinklers) is being built. A wet pipe system with dry barrel sprinklers in false ceiling has been errected, according to NFPA 13.
After that refrigerating units were installed under the false ceiling. They are wider than 4 ft (1,2m) thus we should install dry sprinklers under them. As they are at least 5 ft (1,6m) high, NFPA 13 does not allow installing dry sprinklers below; listed/approved dry sprinkler's length is max. 48" (1,2m). It is not possible to install a drops to sprinklers since it is a wet pipe sprinkler system installed.
How could we avoid installing numerous additional small dry pipe networks to install those additional sprinklers under obstructions (refrigerating units).