SYMPOSIA PAPER Published: 01 January 1994

Concepts Behind ASTM E 931-85: Empirical Practice for Classification of Occupancies for Their Relative Fire Hazard to Life


After the ASTM fire policy was first adopted in 1973, it was established that committee E5 would be responsible for developing fire hazard assessment and fire risk as- sessment standards. Since fire hazard is directly related to the type of occupancy involved, it was quickly recognized that a practice needed to use different criteria depending on the occupancy. Thus, a set of 23 occupancies was developed. The associated hazards were weighted based on empirical hazard ratings associated with issues such as (1) presence or absence of detection or suppression systems or both; (2) factors based on the fire, the occupants, or the type of ignition; and (3) the area available per occupant. A modified Delphi approach was used, based on ASTM committee members, to develop the numerical output. The result was a standard practice originally entitled “Assessment of Fire Risk by Occupancy Classification,” which was published as ASTM E 931, in 1985.

This standard was generated well before proper techniques existed to carry out fire hazard or fire risk assessments. The technology of fire hazard and fire risk assessment has since become more quantitative, and subjective assessments now have insufficient validity. ASTM E5 has also now developed a standard guide for development of fire hazard assessment stan- dards, ASTM E 1546. The definitions of fire hazard and fire risk used by the fire science community have been improved, so that the real focus of the standard was discovered to have been fire hazard, rather than fire risk. Finally, it was discovered that there had been some transcription errors between the values calculated for ASTM E 931 and those actually printed in the standard. An attempt was made to correct the mislabeling (by replacing fire hazard for fire risk) to include the corrected tables and figures and thus develop a modified standard. This was rejected in June 1992 by ASTM subcommittee E5.15, even as an interim measure. A new standard practice, bearing the number ASTM E 931 and entitled “Classification of Occupancies for Their Relative Fire Hazard” will soon be published excluding all numerical values.

Building codes and insurance companies often use occupancy classifications in order to compare the different threats to life or property inherent in the occupancy itself. Such codes control the use of materials, products, or assemblies in buildings. However, they often do not specifically address the potential threat posed by those furnishings or contents brought in by the consumer. The empirical practice described contains guidelines for rating the response of occupancies to a fire on the basis of the predicted threat to life. Thus, this paper was written to aid such potential users by ensuring ASTM archival maintenance of the correct results of the original work, which has had wide empirical use, rather than because the numbers have rigorous validity.

Author Information

Hirschler, MM
Safety Engineering Laboratories, Inc., Rocky River, OH
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Developed by Committee: E05
Pages: 32–49
DOI: 10.1520/STP12947S
ISBN-EB: 978-0-8031-5285-4
ISBN-13: 978-0-8031-1889-8