Non-water based automatic fire extinguishing equipment

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Report: NFPA's "U.S. Experience with Non-Water-Based Automatic Fire Extinguishing Equipment"
Author: John R. Hall, Jr.
Issued: October 2012

Includes statistics on usage and performance of non-water-based automatic extinguishing systems, principally wet or dry chemical systems, including how often they are reported in fires, overall and by major property use reporting their presence, as well as statistics on estimated reliability and effectiveness, as well as leading reasons when systems fail to operate or operate but are ineffective.

Executive Summary

Non-water-based automatic extinguishing systems were reported present in 2% of U.S. reported structure fires in 2006-2010.*  The percentage was higher in places where commercial cooking is common, including eating or drinking establishments (40%) and grocery or convenience stores (25%).  Dry (or possibly wet) chemical systems were the specific type of system specified for most of these fires, and other special hazard systems were the systems cited for most of the rest.

There are some odd patterns in the Table 1-1 statistics.  Fires involving carbon dioxide systems, halogen-type systems, foam systems, and to a lesser extent, other special hazard systems, are not reported primarily in the industrial locations where the first three systems are appropriate but are instead reported primarily in the properties with commercial kitchens, where most dry (or possibly wet) chemical systems are reported, or in residential properties and specifically homes.  This suggests that most of these fires involve either miscoded dry (or possibly wet) chemical systems or possibly portable fire extinguishers, which are not automatic and so should not be reported at all.

Dry (or possibly wet) chemical systems in the area of fire operated in 81% of reported structure fires large enough to activate operational equipment, and therefore failed to operate in 19% (100% minus 19%) of these fires.**  For systems that operated, performance was deemed effective in 69% of the cases.  For fires large enough to activate systems, systems operated effectively 55% of the time (81% times 69%). 

Because the principal application of dry (and possibly wet) chemical systems is as area protection for commercial cooking operations, it may be more appropriate to limit the analysis to fires involving ranges. If this is done, the likelihood of operating increases from 81% to 96%, the likelihood of effectiveness if equipment operates increases from 69% to 90%, and the likelihood of effective operation increases from 55% to 86%.

Nearly half of dry (or possibly wet) chemical system failures (44%) were due to lack of maintenance.  Other reasons cited for failure were as follows:

  • 27% were because manual intervention defeated the equipment,
  • 11% were because a component was damaged,
  • 10% were because the system was shut off, and
  • 8% were because the system was inappropriate for the type of fire.

* These estimates are projections based on the detailed information collected in Version 5.0 of the U.S. Fire Administration’s National Fire Incident Reporting System (NFIRS 5.0) and the NFPA’s annual fire department experience survey. These statistics exclude buildings under construction and cases of failure or ineffectiveness because of a lack of automatic extinguishing equipment in the fire area and after some recoding between failure and ineffectiveness based on reasons given. Some fires after 1999 are coded as confined fires, which are fires confined to cooking vessel, chimney or flue, furnace or boiler, incinerator, commercial compactor, or trash receptacle.  Confined fires permit limited reporting with most data fields not required and usually left blank.  Because nearly all fires reported as confined fires are reported without automatic extinguishing equipment performance details or as fires too small to activate operating equipment, confined fires are not included in any analysis involving reliability or effectiveness of automatic extinguishing equipment. See Appendixes A and B for additional details of statistical methodology, including the distinction between confined and non-confined fires.
** Fire incident reports refers only to dry chemical systems, not wet chemical systems, but wet chemical systems are the only systems now listed for use in commercial kitchens, the most common application of chemical systems. Therefore, we refer to this equipment as dry (or possibly wet) chemical systems.