November Luncheon Seminar – Protection of Exposed Expanded Plastics Stored in Racks; Fire Test Research

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The Chicago SFPE chapter meeting on November 10, 2014, was held at the New Line Tavern, 201 N Clinton Street in Chicago. The speaker was Dan Steppan with UL. Prior to Dans presentation, Carl Baldassara, SFPE International President and long-term member of our chapter, presented a brief update of the SFPE Strategic Plan.

Dan presented recent fire test research work conducted at UL in support of proposed changes to the 2016 edition of NFPA 13 to identify protection criteria of rack-stored exposed expanded Group A plastics. Exposed Expanded Group A Plastics, e.g. Styrofoam, create a significant challenge to a fire sprinkler system due to its extraordinarily quick growth and horizontal fire spread. The protection of these products stored in racks has not been addressed in NFPA 13 to date, due to its severe fire challenge and lack of supporting fire test data. Recent research work conducted at UL provided enough information to generate a proposed revision to NFPA 13 to allow protection criteria in the next edition.

A copy of the presentation can be found HERE. Key observations from the initial Test series, i.e. 1 through test 8, were:

– Exposed, expanded Group A plastics create a unique and substantial challenge to a fire sprinkler system due to the extraordinarily quick fire growth and horizontal flame travel potential.

– The sprinkler protection schemes investigated during this research initiative demonstrated the ability to control ceiling temperatures to a relatively low level (maximum one-minute average steel temperature was 134°F).

– Blocking of transverse flue spaces within the array created a challenging condition for sprinklers to attack the burning combustibles.

– Vertical barriers installed demonstrated ability mitigate horizontal fire travel within the array

The second draft meeting of the full discharge committee was held at the end of June 2013, which finalized their positions on the revisions to NFPA 13, including the following language:

Proposed Revisions to NFPA 13 in First Draft for 2016 Edition, Key Criteria in a New Section in Chapter 17 for the Protection of Rack Stored Exposed, Expanded Plastics:

– Maximum storage height = 35 ft.

– Maximum ceiling height = 40 ft

– Minimum aisle width = 8 ft.

– Nominal K=25.2 Pendent ESFR intermediate temperature rated sprinklers

– Minimum design pressure = 60 psi

– Design area = 12 sprinklers (4 sprinklers on each of 3 branch lines)

– Minimum water duration = 60 minutes

– Minimum hose allowance = 250 gpm

– Maximum vertical barrier distance = 16.5 ft.

– Vertical barrier material = 3/8 in plywood, 22 gauge steel or equivalent

– Maximum area between vertical barriers and aisles = 124 ft2

– Vertical barrier to extend across longitudinal aisle to top of storage

– Commodity permitted to extend 4 inches beyond vertical barrier at aisle

The FPRF Technical Panel then met and decided to fund test 9 and 10 as an attempt to look at a reduction in discharge pressure for a reduction in ceiling height. 30 psig flowing pressure for a maximum ceiling height of 30 ft. was selected to test.

Tests were both successful in that it both had 7 operating sprinklers, keeping intact the 12 sprinkler design criteria. (A 1.5X safety factor is required in accordance with paragraph 21.1.8 of NFPA 13, 2013 Edition).

A complete FPRF Report can be found at www.nfpa.org/foundation

(submitted by K. Mniszewski, 11/18/14)