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June 2008: Changes to FM Global Data Sheet 8-9 "Storage of Class 1, 2, 3, 4 and Plastic Commodities"

The January 2008 revision to this data sheet resulted in significant changes. This data sheet was completely rewritten. Some changes were minor while others resulted in significant modifications to sprinkler designs needed for several commodities. The changes occurred due to several factors. Some of them were to make this data sheet easier to use and others were due to recent test results and changes in materials over the last several years.

One change is the preferred sprinkler head temperature. The preferred temperature for sprinklers for storage applications is now 160°F due to the quicker operation of sprinklers allowing quicker control of fires. It was previously believed that higher temperature sprinklers would better control a fire, as this would help to ensure that there would not be an excessive amount of sprinklers operating.

On another note, recent tests have shown that a higher sprinkler density is needed to properly control fires involving storage when control mode density area (CMDA) sprinklers are used. Thus, the ceiling sprinkler densities have been increased.

Several factors have led to this storage becoming more challenging to protect. A few of these are: the use of more recycled materials, the trend towards increased building heights in recent years, and changes to products and packaging. These changes have resulted in negative factors such as: materials burning hotter, materials not absorbing sprinkler water as well, and an increased distance between the fire and the sprinklers. This increased distance causes more time to pass before sprinklers operate and makes it more difficult for sprinkler water to reach the fire.

Along with increased ceiling sprinkler densities, several higher challenge storage arrangements now need in-rack automatic sprinklers (IRAS). In fact, the maximum building height for ceiling only protection for CMDA sprinklers is 30 ft. IRAS are now recommended for any type of combustible storage when the building height exceeds 30 ft. The terminology for IRAS is also different due to changes in the arrangements for these sprinklers. Now four separate terms are used, as follows:

Another change is that the minimum K-factor for sprinklers in storage areas is now 11.2. This means that the two smallest sized sprinklers used for commercial applications should not be used for storage applications. Due to certain minimum flow and pressure requirements for sprinklers to operate properly, this results in a minimum sprinkler design for storage to be 0.30 gpm/sq. ft. over the most remote 2,000 sq. ft. Due to this change, Class 1 (mainly non-combustible materials) and Class 2 (mainly Class 1 materials in cardboard containers) have been condensed and now have the same sprinkler requirements.

Not all of the changes to this Data Sheet have resulted in increased sprinkler designs. Some of the changes have made this Data Sheet easier to use.

There is now a definition for the largest width of a flue space. Previously, this was not defined. The maximum width of a flue space is now 2 ft. Vertical openings wider than this are considered aisles.

Additionally, interpolating between storage heights is no longer recommended. The old Data Sheet encouraged the user to interpolate between storage heights. Now sprinklers should be designed to the next storage increment if this storage has a height that is between the designated heights listed on the tables.

There are now separate tables to determine the protection needed for dry sprinkler systems. Previously, tables for wet sprinkler systems were used and 30% had to be added on to the design area.

Also, steel column protection is not needed when the sprinkler system is designed as recommended in this new Data Sheet.

You may be asking what this means for your facility. If your facility uses NFPA Standards, then this does not mean any changes for you at this time. However, NFPA may incorporate some or all of these changes in the future. Thus, this could lead to changes in requirements for sprinkler system design down the road. Historically this has happened in the past where NFPA utilizes FM test data to update their protection standard.

If your facility uses FM Global Standards, then this would at least mean that any new sprinkler system installations should be designed to meet this new Data Sheet. It appears that the use of K-factor 11.2 sprinklers will not be retroactively applied. Thus, lighter hazard storage arrangements likely will not need to be upgraded. However, it appears that the new recommendations for higher hazard storage will be retroactively applied. This will result in Plastic and Class 4 rack storage arrangements (that use ceiling only CMDA sprinklers) to be considered inadequately protected. In many cases, the addition of in-rack sprinklers would likely satisfy the new design standards in this Data Sheet. However, this will depend on current storage arrangements and the sprinkler protection that is currently available.

Risk Logic can help you determine if your sprinkler system would need to be upgraded as part of the changes made to this Data Sheet.