Factory Mutual Global has announced that it will be issuing a revised Data Sheet 8-9 in May of 2001 that will no longer permit the use of K-14 and K16.8 (metric K-200 and K-240) ESFR sprinklers for palletized storage up to 35 ft (10.7 m) under a ceiling/roof height of up to 45 ft (13.7 m), and will require one level of in-rack sprinklers to protect rack storage to those same heights.  The change is being made based on consideration of an "offset ignition scenario" that was used by Underwriters Laboratories in evaluating the sprinklers, and which showed that excessive sprinklers could operate under specific arrangements at these protection limits.

Although UL never acknowledged a protection capability for the K14 or K-16.8 ESFR sprinklers for 35 ft of storage under a 45 ft roof, the 1999 edition of NFPA 13 included this allowance within Table 7-9.5.1.2 on the basis of the earlier FM approval.  A proposal has been tentatively approved for the next (2002) edition of NFPA 13 that will eliminate this allowance.

The change is not being processed as a Tentative Interim Amendment and is therefore not being considered an emergency.  However, specifiers and contractors should be aware of the pending limitations on the use of the K-14 and K-16.8 ESFR sprinklers.  The UL listing of these sprinklers is unchanged by the Factory Mutual action, but it is possible that some Authorities Having Jurisdiction will interpret the basis on which UL lists the devices to preclude their use in the manner allowed by the 1999 edition of NFPA 13.
Read the FM Press Release