Monday, May 7, 2018

What kind of plastic is it?



To provide effective fire sprinkler protection within a structure, the hazard classification and commodity must be known. For the protection of rack storage, the storage and shelving configuration must be known. Due to the high speed and temperature of burning plastics, they require special consideration.  NFPA 13, Standard for the Installation of Sprinkler Systems, requires all plastics, elastomers, and rubber, to be classified as Group A, Group B, or Group C.


A complete list of Group A plastics is provided in 5.6.4.1 and Table A.5.6.4.1, of NFPA 13. This group of plastics includes rubber, poly(s)-, cellulosics, and nylon. Group A plastics are further divided into expanded or unexpanded. Expanded plastics are “low-density materials” commonly referred to as “foam plastics”. Unexpanded plastics must meet one, of six, criteria listed in listed in section 5.6.4..1.1.2. Group B plastics include chloro-, fluoro-, and silicone products. There are seven materials classified as Group C plastics.  This group include the polyvinyl- products. A complete list is provided in section 5.6.4.3.


Sprinkler design criteria for the protection of plastics is outlined in Chapter 15 and Chapter 17 of NFPA 13. If the plastics are Group A and do not exceed 5 feet in height then the protection requirements of Chapter 13, Protection of Miscellaneous and Low-Piled Storage, can apply. For all plastic or rubber commodities that exceed 5 feet in height, section 15.2.2 outlines the fire protection requirements. For clarity and protection requirements the decision tree provided in figure 15.2.2.1 of this standard should be referenced.


If the stored items are plastic or rubber commodities and on rack storage the protection requirements of Chapter 17 shall be enforced. This section has a decision tree that must be followed based on the group of plastics being protected, as well as alternate provisions for systems that do not meet minimum design requirements. If plastic or rubber commodities on rack storage is encountered, this chapter should be closely examined.