The recently released June 2015 edition of FM Global Property Loss Prevention Data Sheet 8-9, Storage of Class 1, 2, 3, 4 and Plastic Commodities, contains several changes from the previous version. A few of the more prominent revisions are as follows:
- Reduced demand pressure requirements for K22.4 quick response (a.k.a. early suppression fast response or ESFR) pendent heads for nearly all Class 1 through 4 and plastic commodities storage scenarios. FM Global’s K22.4 quick response pendent head pressure demands previously were in line with those for K16.8 quick response pendent heads, but now are more in line with K25.2 QR pendent head demands. Without getting too technical, the lower, revised pressure demands make sense as the K22.4 and K25.2 heads are closer in overall design and hence, performance, than the K16.8 and K22.4. The Data Sheet indicates this revised protection criteria was developed during recent, updated fire testing.K22.4 quick response (ESFR) pendent sprinklers may be the best protection option for storage of Class 1 through 4 commodities and cartoned unexpanded plastics in buildings up to 45 ft. high due to the lower design pressures required compared to K14 and K17 pendent ESFR sprinklers, and required lower overall water demand when compared to K25 ESFR sprinklers. K22.4 ESFR pendent heads could be especially useful in areas with gravity fed, city water supplies with moderate pressures available as you may be able to avoid installing a fire/booster pump.
The revised FM Global K22.4 quick response (ESFR) pendent sprinkler demands are actually lower than those in the current (2013) edition of NFPA 13, Standard for the Installation of Sprinkler Systems, for most storage scenarios in buildings up to 35 ft. high. This is important to note as you may be able to design your sprinkler system to the lower FM Global requirements if acceptable by the local code official (Alternate materials, design and methods of construction and equipment may be accepted in accordance with International Building Code). This lesser design could allow the use of smaller sprinkler piping and/or a smaller fire / booster pump, which could provide a significant cost savings for a project.
In buildings over 35 ft. up to 45 ft. high, the FM Global and NFPA demands may be the same or different based on storage height.
- Reduced demand pressure requirements for K22.4 quick response (a.k.a. early suppression fast response or ESFR) pendent heads for nearly all Class 1 through 4 and plastic commodities storage scenarios. FM Global’s K22.4 quick response pendent head pressure demands previously were in line with those for K16.8 quick response pendent heads, but now are more in line with K25.2 QR pendent head demands. Without getting too technical, the lower, revised pressure demands make sense as the K22.4 and K25.2 heads are closer in overall design and hence, performance, than the K16.8 and K22.4. The Data Sheet indicates this revised protection criteria was developed during recent, updated fire testing.K22.4 quick response (ESFR) pendent sprinklers may be the best protection option for storage of Class 1 through 4 commodities and cartoned unexpanded plastics in buildings up to 45 ft. high due to the lower design pressures required compared to K14 and K17 pendent ESFR sprinklers, and required lower overall water demand when compared to K25 ESFR sprinklers. K22.4 ESFR pendent heads could be especially useful in areas with gravity fed, city water supplies with moderate pressures available as you may be able to avoid installing a fire/booster pump.
- Based on recent fire testing, there were several changes in the design criteria for K25.2 quick response (ESFR) pendent heads for uncartoned plastics. Demands were decreased in general for lower building heights and increased for higher building heights.Corresponding demands in NFPA 13 do not exist in most cases for K25.2 ESFR heads. The NFPA 13 demands that do exist for uncartoned (exposed) unexpanded plastics are lower (12 heads operating at 50 psi vs. 12 heads operating at 60 psi) than FM Global’s.
- Increased maximum linear (from 12 to 14 ft.) and area (from 144 to 196 sq. ft.) spacing for K25.2EC sprinklers as noted in Table 1. These revised maximum spacings are in line with NFPA 13. These sprinkler heads are often used in “big box” retail stores.
- Alternative in-rack automatic sprinkler (IRAS) designs are now available as noted in Section 2.3.6.6. This involves using K14 and larger quick response (ESFR) pendent sprinklers as IRAS. This protection scheme may prove beneficial in buildings with very high storage racks / ceiling heights (i.e., over 45 ft. high). There is currently no such alternative provided in NFPA 13.
- A new retrofit IRAS protection solution for uncartoned plastics currently protected by IRAS only in the longitudinal flue spaces (see Section 2.3.6.7). This new IRAS protection scheme involves installing K22.4 quick response (ESFR) pendent heads. There is currently no such alternative provided in NFPA 13.
- The hose stream and required duration for Protection Scheme 8-9A (protection scheme consisting of a combination of IRAS and horizontal barriers) have been cut in half to 250 gpm and 1 hr., respectively. This could significantly decrease the overall water volume needed for a facility when Scheme 8-9A protection is provided. At a new facility with a planned fire pump, this could allow you to use a pump with a lower flow rating and a much smaller suction source (i.e., tank, cistern, reservoir, etc.), which could lead to a cost savings.
Risk Logic can help you design adequate automatic sprinkler protection (using FM Global or NFPA standards) for the storage at your facility. Please contact us for additional details.