Special Study of Safety in Pyrotechnics Manufacturing
Abstract
In June 1989, a fire and deflagration occurred at one of the Army ammunition plants (AAPs). The plant was mixing an Infrared (IR) Decoy Flare composition in a mixing bowl when the incident occurred. The bowl contained 200 pounds of mixture which included magnesium, teflon, acetone, hycarb binder, and hexane. A Board of Investigation (BOI) was formed immediately to identify a potential cause(s). As a result of the investigation, the BOI concluded that the most probable cause of the fire and deflagration was electrostatic discharge into the mixture. The plant was using a Cowles Dissolver System. The mixing bowl had been teflon coated to facilitate removing the mixture from the bowl as well as the clean-up process. However, the coating acted as an insulator and created some lack of grounding between the mixer bowl and the mixer shaft. A reading was taken of potential differences between the hexane dispenser tube and the mixer shaft and a net potential difference of 1,800 volts was found. A video tape taken of the operation at the time of the fire did, in fact, indicate a one-point initiation at precisely that location in the mixer bowl. A subsequent interview with one of the operators revealed that the flow of hexane into the mixer bowl had decreased that day by 50% as compared to the flow the day before. The BOI deduced that the decreased hexane flow increased the vapors in the mixer bowl and an electrostatic discharge ignited the hexane vapors which then ignited the flare composition.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 30, 1990
- Accession Number
- ADA527407
Entities
People
- John A. Johnson