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Fire risk assessment as a tool
Assessment improves the overall level of safety in our codes and standards

NFPA Journal®, March/April 2007

The aim of NFPA’s fire safety codes and standards is to protect and if possible enhance the safety of the public and emergency personnel in buildings and other structures. What is the top complaint from industry about the way those codes and standards operate? That they lack the flexibility to accept, support, even stimulate newer, better designs and solutions. What is the top complaint from safety authorities? That the flexibility they do have provides too much room for unsafe designs to slip through the review process.

How do we welcome good new ideas while holding back bad new ideas? How do we move quickly to remove newly recognized threats without throwing out the baby with the bathwater for every innovative approach? One way is to change the way we think about and talk about codes and standards.

During the code revision process, proposals are received, sometimes accompanied by detailed information documenting the hazard or hazard-mitigation strategy. The challenge for NFPA Technical Committees is to evaluate these proposals in the context of current provisions, which are often based on historical consensus or rules of thumb. In the current setting, the emphasis is on code or standard compliance, but that may not be the same thing as fire performance. If we want to welcome good new ideas while rejecting bad new ideas, we need a better way to recognize both. The language of fire risk may be a way to discuss fire performance directly instead of through the proxy of compliance.

The Fire Protection Research Foundation has recently completed two projects that both illustrate this dilemma and present a means to address it.

The primary goal of the first project was to develop technical information to support new requirements in NFPA 55, Storage, Use and Handling of Compressed Gases and Cryogenic Fluids in Portable and Stationary Containers, Cylinders, and Tanks , for storing relatively small amounts of hydrogen (used for fuel cells for backup power systems) in metal storage cabinets.

This project focused on determining the hazard posed by a variety of scenarios involving the release of hydrogen from a storage enclosure and associated equipment. The hazard was estimated using computer simulations, and the results were used to determine siting requirements for various types of outdoor threats or targets such as adjacent buildings. The project was hazard based – i.e., neither the probability of the release scenarios occurring nor the probability of the consequence occurring (i.e., ignition of a deflagration or detonation) was considered. In contrast, the current spatial separation requirements for other gases in the standard were developed many years ago on a strictly prescriptive basis using neither a quantified hazard nor a risk approach. The challenge for the Industrial and Medical Gases Committee will be to reconcile the distances developed in the study with those currently in the standard.

Fire risk assessment (FRA) is a tool available to address these issues. It can be defined as a process for estimation and evaluation of fire risk that addresses fire scenarios and fire scenario clusters, with associated probabilities and consequences, using one or more acceptability thresholds. Using this tool, committees can better evaluate the relative impact of various hazards and protection methods on fire safety, such as the hydrogen study discussed earlier.

In 2006, the Foundation received a USFA Fire Prevention and Safety grant to develop a guidance document to assist NFPA committees in incorporating risk concepts. The guide has been developed and proof tested with the NFPA Cultural Resources Committee as well as representatives from a broad range of NFPA’s committees. It has three major sections: determining the usage of FRA concepts by a technical committee, risk-informed criteria, and applying fire risk assessment methodologies. The guide is available on the Foundation’s Web site at www.nfpa.org/foundation.

As our understanding of hazard and risk and their application to codes and standards improves, we will improve the overall level of safety in NFPA codes and standards.