Classify & Conquer
A research blueprint for bigger, better hazardous materials standards.

NFPA Journal®, July/August 2009

The Fire Protection Research Foundation recently completed a study conducted by Fluer, Inc. that documents the background of the current national hazardous material classification system, focusing on threshold limits and its technical basis. This system was first developed during the 1960s, when workplace safety emerged as a key concern in the United States. The U.S. Department of Labor reported that disabling workplace injuries increased 20 percent during the decade and that 14,000 workers died on the job each year. Workers had to be protected from hazards such as noise, cotton dust, and asbestos.

Between 1970 and 1986, significant federal legislation affecting the storage and use of hazardous materials was enacted, raising the awareness of code officials throughout the country to the public’s concerns. The reporting systems, which in some cases required notification of local authorities, including fire departments, increased awareness among local communities, and, in some instances, led to questions about the suitability and practices of facilities operating in certain communities.

In the 1980s, a system for classifying hazardous materials and setting thresholds for the amounts of these materials that could be used or stored in a fire control area was introduced into the Uniform Fire Code®. If a facility exceeded the thresholds, its occupancy designation would change to a hazardous occupancy, requiring a defined set of additional fire protection measures to be implemented. This system of classification was later transferred to the International Fire Code®; NFPA 5000®, Building Construction and Safety Code® ; and NFPA 1, although the required protection measures differ in each code. It has become the pre-eminent national hazardous material classification system and is now being implemented in the new NFPA 400, Hazardous Materials Code.

The Foundation’s recent study provides a fascinating history of the social and policy drivers behind hazardous materials regulation and the evolution of regulation in building codes and standards, including the development of the control area and concepts of maximum allowable quantities. As the classification system developed, there were inevitable shortcomings, and the Fluer report identifies a number of anomalies and inconsistencies, including the need for a quantitative method for classifying solid and liquid oxidizers, oxidizing gases, unstable reactive materials, and organic peroxides. These topics provide a blueprint for  research designed to further develop the technical basis for NFPA standards.

The Foundation is addressing one of these issues with another project on the classification of oxidizers. NFPA 430, Liquid and Solid Oxidizers, has never contained tests or criteria for this classification. Instead, oxidizers listed as typical of each class are based on information from manufacturers and historical fires. On occasion, the committee has classed or re-classed specific oxidizers based on the results of extensive and nonstandardized reaction-to-fire tests with oxidizers in their intended form and packaging. Further, revisions to the code have included changes to the definition of an oxidizer, as well as the subjective descriptions used to define each class, without a contemporaneous review of the oxidizers listed in the annex as typical of each class.

The Foundation’s current study, conducted by the Fire and Materials Laboratory, LLC, involved more than 200 bench-scale screening tests and 32 intermediate-scale fire exposure tests with varying oxidizers and packaging to explore meaningful criteria for hazard classification. The result is a proposed test method at both the bench- and intermediate-scale and criteria designed to provide a technical basis for the classification of oxidizers based on the energy released as a result of its involvement in a fire.

This study is a model for future efforts designed to improve our hazardous materials classification system.