- Author
-
Eggleston, L. A.
|
Pish, M. D.
- Title
- Requirements for Explosion-Proof Electrical Equipment in Air Force Hangars. June 1971-July 1972
- Coporate
- Southwest Research Institute, San Antonio, TX
- Sponsor
- Air Force Weapons Lab., Kirtland AFB, NM
- Report
-
AFWL-TR-72-135,
August 1973,
125 p.
- Distribution
- Available from National Technical Information Service
- Contract
- F29601-71-C-0116
- Keywords
-
aircraft hangars
|
electrical equipment
|
experiments
|
explosibility index
|
leakage
|
fuel spills
|
codes
- Identifiers
- lower explosive limit (LEL)
- Abstract
- The objective of this research effort was to determine if current requirements for explosion-proof equipment in USAF hangars are more stringent than necessary, and thereby result in unnecessary expense in meeting such requirements. Experiments and tests conducted, both in actual USAF hangars and in the laboratory, indicated that the vapor explosibility hazard from leaks and fuel spills is lower than generally believed. The results of this study indicate that hazardous zone definitions in existing codes could be relaxed without compromising safety. Vertical profile measurements of fuel spills and fuel leak vapors showed that under normal conditions of ventilation, the atmosphere in the 2-in. level was well below the lower explosive limit (LEL). Even with the extreme condition of volatile fuel spills in quiescent, confined spaces, the LEL level did not rise above 7 inches. It was concluded, therefore, that all portions of hangar spaces more than 12 in. above the floor could be considered as nonhazardous with respect to vapors from aircraft fuel spills and leaks relating to explosion-proof equipment requirements. In view of this, it further concluded that the 18-inch upper boundary in existing National Electric Code (NEC) and the Occupational Safety and Health Act (OSHA) requirements are more than adequate to ensure safety.