An investigation has been carried out of the limiting oxygen index (LOI) test. A review of the literature shows that, although there is abundant information on the test, it is not clear that its results correlate well with those of any other test, or indeed with those of real fires. Theoretical considerations indicate that the test could be improved by using it with bottom ignition rather than with the standard top ignition. A number of materials were tested in the cone calorimeter and in the LOI, and various correlations were attempted. In general, correlations between some of the cone calorimeter properties measured and the inverse of the LO1 made sense. These correlations were not, however, sufficiently sensitive, even when investigating small effects on a single base polymer system, to justify using the LO1 as a proxy for the cone in any way. The LO1 is likely to continue to be used extensively. This work suggests that quality control and, possibly, mechanistic or other flame-retardant additive studies, are its only applications where the results can be justified.

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This paper presents a survey of the fire safety of flexible and rigid polyurethane foam. The principal uses of flexible polyurethane foam are in applications where full resiliency is required, namely in upholstery for furniture, mattresses, and filled bed products. A subcategory of this type of application is the use of the foam in transportation seating, including every type of vehicle: automobiles, buses (and school buses), trains (and subways), ships, and aircraft. The fire safety legally required for these various environments covers a broad range, between virtually nothing for private automobiles and the extreme fire safety associated with airplane seats. Polyurethane foam also forms part of construction products, and in this case the foam is generally not applied exposed (since this is almost never allowed) and is often used as part of composite systems. The fire testing is normally conducted in the composite application, with severe restrictions to general uses. Overall, polyurethane foam can be used safely for applications that require adequate fire safety only if it is appropriately fire‐retarded or if the correct type of fire barriers (or alternate product design) is used. Copyright © 2008 John Wiley & Sons, Ltd.

Summary This work is the second of two parts that considered the following issue: do flame retardants affect heat release of polymers? The reason for investigating the issue is because it is important to assess whether the addition of flame retardants positively decreases fire hazard. This part of the work considered the two following issues. (1) Analysis of the individual polymeric materials that need to be studied. (2) Analysis of the data found on heat release (particularly peak heat release rate), ignitability (if available), and other thermal properties (as available) of polymers in small‐scale test data in recent years. The effects are being presented in terms of the percentage of improvement. The work demonstrated that, almost without exception, when adequately compounded systems were developed, the peak heat release rate of the flame retarded system was lower than that of the non‐flame retarded system. The overall conclusion of the two‐part study was that flame retardants does indeed improve fire safety (when used appropriately) and that a key reason for the beneficial effect of flame retardants is that they decrease heat release. Copyright © 2014 John Wiley & Sons, Ltd.

SUMMARYThis is part of a project considering whether flame retardants affect polymer heat release, a critical issue to assess whether adding flame retardants decreases fire hazard. The work investigated the following. (1) Fire properties affecting fire hazard, confirming that heat release rate is the key fire property most strongly influencing fire hazard. (2) Ways to assess heat release and whether full scale fire heat release rate can be predicted from small scale test results, confirming that cone calorimeter and OSU data are adequate to predict full scale heat release. (3) Analysis of key 1988 NBS/NIST study comparing the fire hazard of flame retarded products versus non-flame retarded products for the same application. This confirmed that the study demonstrated that flame retardants lower fire hazard and that the levels of additives in the flame retarded products used were not excessive. (4) Review of studies investigating effects of flame retardants on various polymeric systems. The overall conclusion is that flame retardants do indeed improve fire safety (when used appropriately) primarily because they decrease heat release. Part 2 of the project (separately) considers the key polymers that need to be potentially flame retarded and reviews recent studies on effects of flame retardants on heat released by such polymers.