Clean Agent Supression of Energized Electrical Equipment Fires

Fire Protection Research Foundation report: "Clean Agent Suppression of Energized Electrical Equipment Fires(PDF, 959 KB)
Author: Gregory T. Linteris, Ph.D., Building & Fire Research Laboratory, NIST
Date of issue: January 2009


Clean agent fire extinguishing systems utilize clean agent gaseous chemicals for the protection of certain fire hazards in today’s world. Clean agents are gaseous extinguishing agents that leave no residue behind and do not conduct electricity. Clean agents include both halocarbon and inert gaseous agents.

A typical fire hazard fuel array is generally classified according to a well-recognized classification scheme (Class A, B, C, D, or K), and Class C fires are those that involve energized electrical equipment. Normal protection methods attempt to de-energize the electrical equipment to minimize the fire challenge of Class C fires (also referred to as energized electrical equipment fires or energy augmented combustion). However, it may be necessary to provide protection for scenarios where the power cannot be removed and the performance of clean agents on such fires is not completely understood.

The optimal design of clean agent fire extinguishing systems for energized electrical equipment depends on: (a) defining the hazard to be protected, and (b) establishing the appropriate design parameters. Defining the hazard depends on the type of electrical equipment, the worst case anticipated level of energy, and the nature of the unwanted fire that might require control. Establishing the appropriate design parameters primarily requires determining the clean agent extinguishing concentrations for each type of clean agent, but additionally considers other factors such as minimizing secondary adverse effects (e.g., minimizing the generation of products of decomposition).

This study seeks to define the anticipated hazards for applications involving Class C fires (energized electrical equipment) that normally require protection by clean agent fire extinguishing systems, and to develop a proposed test protocol that will provide the scientific basis for determining the minimum extinguishing concentrations required to protect typical energized electrical equipment using clean agent extinguishing systems.

The Research Foundation expresses gratitude to the report author Dr. Gregory T. Linteris of the Building & Fire Research Laboratory at the National Institute of Standards and Technology. In addition, the Research Foundation appreciates the guidance provided by the Project Technical Panelist, and all others that contributed to this research effort. Special thanks are expressed to the following project sponsors for providing the funding for this project: 3M Fire Protection; American Pacific Corporation; DuPont Fluoroproducts; Electric Power Research Institute; Fike Corporation; Fire Suppression Systems Association; FireTrace International; Kidde/Chemetron Fire Systems; National Association Fire Equipment Distributors; Nuclear Electric Insurance Ltd.; TYCO Safety Products/Ansul Inc.; and Underwriters Laboratories Inc.

The content, opinions and conclusions contained in this report are solely those of the author