Life Safety and Fire Analysis - Aircraft Hangar

Author

Frederick J. Tanis Jr., California Polytechnic State University, San Luis ObispoFollow

Date

6-2018

Degree Name

MS in Fire Protection Engineering

College

College of Engineering

Advisor

Frederick Mowrer and Christopher Pascual

Abstract

A hangar originally built in 1958 then modified and expanded over the years was evaluated using both the prescriptive requirements and a performance analysis. For the prescriptive analysis the building was evaluated against the 2015 International Building Code and the current NFPA codes and in a few cases the Department of Defense (DoD) Unified Facilities Criteria (UFC). During the prescriptive analysis a few areas were identified that do not meet the current codes due to areas being broken up into separate rooms and hallways and rooms being separated by security doors that only allow unobstructed travel in one direction. These modifications over the years have created a few areas that have a common travel paths and dead ends that exceed the requirements as set forth by NFPA 101 Life safety code. Due to the size of the hangar the notification devices installed do not meet the audibility or illumination requirements. It is recommended that the rotating beacons be installed per the new UFC 4-211-01 requirements. For the performance analysis a pool fire created from jet fuel was ignited both under the aircraft and in the vicinity of an aircraft. The hangar was then evaluated for both life safety by verifying that the available safe egress time (ASET) was greater than the required safe egress time (RSET). The RSET was calculated using both hand calculations and a pathfinder computer model. The ASET was determined using a NIST Fire Dynamic Simulator (FDS). The FDS modeling showed that the ASET was significantly greater than the RSET thus there was no issue with life safety. Asset protection from the fire scenarios chosen was not as promising. For both fire scenarios chosen in the hangar the aircraft suffered some damage. It was also determined from the modeling that the current activation sequence of the high expansion foam (HEF) system, using the sprinkler flow switches to activate the system, would be ineffective due to the delay in activating the sprinklers at the 70-ft ceiling level and the mechanical timer in the flow switch. A better way to activate the HEF system would be using multiple optical flame detectors as now required by UFC 4-211-01.