Class 'D' lab as per NFPA45 requires OH1 sprinkler design and NFPA 45 (2015) 6.1.12 notes that “Fire sprinklers in laboratory units shall be the quick-response (QR) sprinkler type installed in accordance with NFPA 13.”.
However notes that - (A.18.104.22.168 ) A series of fire tests in typical chemical laboratories was conducted to evaluate quick-response sprinkler technology and the use of quick-response sprinklers in chemical laboratories. Fire test results demonstrated that both standard-response and quick-response sprinklers were effective in controlling fires. Additionally, fire test results of the quick-response sprinklers showed lower maximum temperatures at the 5 ft level consistent with what is considered acceptable tenability in the room of fire origin, as discussed in NFPA 13D, and evaluated by ANSI/UL 1626, Residential Sprinklers for Fire Protection Service. Also see NISTIR 89-4200, “Quick Response Sprinklers in Chemical Laboratories: Fire Test Results,” sponsored by the National Institutes of Health, Bethesda, MD.
So does this mean that QR sprinklers are not mandatory?