- Author
- Williams, F. W. | Beller, R. C. | Burns, R. E. | Scheffey, J. L.
- Title
- Alternative AFFF Proportioning Systems for the SSN 21 Design--T&E. Interim Report. October 1985-January 1986.
- Coporate
- Naval Research Lab., Washington, DC
- Report
- NRL Memorandum 5778, June 2, 1986, 21 p.
- Distribution
- Available from National Technical Information Service
- Keywords
- fire extinguishers | fire suppression | fire extinguishing agents | flammability | flow | sprinklers
- Identifiers
- fire extinguishing agents
- Abstract
- The Aqueous Film Forming Foam (AFFF) fire suppression systems proposed for flammable liquid fuel hazards on the SSN 21 require proportioning systems to inject 3 percent AFFF concentrate into seawater systems to create AFFF solution. Alternative proportioning systems, each of which utilizes an air-pressurized concentrate storage tank, are being regulated by the Naval Research Laboratory (NRL). One candidate system uses multiple single-user injection points (e.g., orifice metering plates) to proportion AFFF at each hose station or sprinkler system. The other system, which uses an in-line balanced pressure proportioner and ratio controller, is designed as a central system which can proportion over a range of demands. Proportioning using the orifice plate system pressure sensitive and not flow sensitive. If the pressure differential can vary considerably during operation, AFFF flow and storage requirements must be overdesigned to meet the lowest design point, i.e., 3 percent at the smallest pressure differential. The size of the orifice in the orifice plate design may be so small (e.g., 0.1 in. dia.) that clogging of the orifice could be a problem.