FM Global Standard Commodities

The fire growth characteristics for the Li-ion batteries and the FM Global standard commodities that were evaluated exhibited similar fire development leading to the estimated time of first sprinkler operation. 

Two FM Global standard commodities were selected for this project Class 2 and Cartoned Unexpanded Plastic (CUP). The Class 2 commodity consists of three double-walled corrugated paper cartons. Inside the cartons is a five-sided sheet metal liner, representing non-combustible content and the cartoned liner is supported on an ordinary, two-way, slatted deck, hardwood pallet (see Fig. 2.1). 

Thirteen reduced-commodity fire tests were conducted focusing on a comparison of the flammability characteristics of FM Global standard commodities and the three types of cartoned Li-ion battery products. All tests were free bum fire tests that measured the heat release rate and the evaluated time of battery involvement for the Li-ion products. Each test was conducted in a two by one by three high pallet load rack storage arrangement that represents storage up to 15 ft tall. 

The four monitoring techniques utilized to evaluate propagation penetration in the commodity included standard video cameras to monitor the location of flame attachment infrared imaging cameras to monitor external heating of the commodity thermocouples attached to the commodity-metal liner interface to monitor internal heating of the commodity and product collapse. The FM Global standard commodities did not exhibit collapse before termination of the fire test and are not discussed. 

Fig. 3.3 Convective heat release rates for FM Global standard commodities and Li-ion battery commodities (courtesy of FM Global)...

Small format Li-ion battery commodities were selected to represent commercially available battery formats and Li-ion battery containing devices. The selected Li-ion battery types were individual 18,650 format cylindrical cells, power tool packs comprising 18,650 format cells, and polymer cells. The selected comparison commodities were the FM Global standard Class 2 and Cartoned Unexpanded Plastic (CUP). Two independent test series were conducted by FM Global. These tests represented a unique approach to hazard evaluation with limited commodity and were necessary due to the inordinate cost associated with Li-ion batteries. 

The first test series evaluated the flammability characteristics of small format Li-ion batteries and the FM Global standard cartoned commodities in a three-tier high, single row, open frame, rack storage array. All tests conducted were free burn tests. In each test, cartoned commodity was only located in a portion of the rack where the initial fire growth was expected to lead to sprinkler operation (i.e., at the flues). The first test series was used to estimate the fire hazard from the cartoned commodity present at the time of the predicted first sprinkler operation. 

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