Preventing Hydrogen Sulfide Formation in Shipboard AFFF Fire Protection Systems
Abstract
There is a very serious problem aboard U.S. Navy ships from generation of toxic hydrogen sulfide (H2S) in Aqueous Film Forming Foam (AFFF) solutions used for shipboard fire protection. This is the result of the action of sulfate reducing bacteria (SRB) in mixtures of seawater and AFFF, which remain stagnant for significant time periods in shipboard fire protection system piping. Over time, microbes present in seawater consume organic materials in the AFFF mixture and can deplete the dissolved oxygen. If the reduction-oxidation potential falls low enough, anaerobic action of the SRB on the sulfate present in seawater can then result in H2S generation, reaching dangerous levels. The recommended ceiling for exposure to hydrogen sulfide is only 10 ppm. If the microbes causing oxygen depletion and / or the sulfate reducing bacteria can be eliminated (or sufficiently minimized), the dangerous generation of H2S would not occur. The Navy Technology Center for Safety and Survivability is participating in a research project for the Naval Sea Systems Command (NAVSEA) to evaluate several treatment modalities for their ability to inhibit hydrogen sulfide formation in AFFF/seawater mixtures and for possible deleterious effects on AFFF performance. Various approaches have been considered employing laboratory evaluations (dynamic surface tension and Ross-Miles foamability), and 28 ft2 pool fire extinguishment and burnback protection field tests (Military Standard MIL-F-24385F). The protocol selected for NAVSEA shipboard H2S generation mitigation testing is a combination of a commercial broad spectrum biocide with a molybdenum compound which is a specific inhibitor of SRB.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2007
- Accession Number
- ADA573086
Entities
People
- Bradley A. Williams
- Ronald S. Sheinson
Organizations
- United States Naval Research Laboratory