The model VK506 is a cULus Listed and FM Approved, Early Suppression Fast Response (ESFR) type storage sprinkler capable of suppressing specific high-challenge fires.  ESFR sprinklers can eliminate the use of in-rack sprinklers when protecting high-piled storage of certain specified materials up to: UL: 40 ft. (12,2 m) with ceilings up to 45 ft. (13,7 m)* FM: 45 ft. (13,7 m) with ceilings up to 50 ft. (15,2 m)* They can also reduce or eliminate the need for a system fire pump and provide flexibility when sizing system piping.  Viking VK506 ESFR Pendent Sprinklers are primarily intended to protect the following types of storage, which tend to produce severe-challenge fires: palletized and solid pile storage and single, double, multiple row, and portable open rack storage (no open-top containers or solid shelves). * Refer Technical Data, Approval Charts and Commodity Selection and Design Criteria Overview for cULus Listing and FM Approval requirements that must be followed.