- Author
-
Verdonik, D. P.
|
Darwin, R. L.
|
Williams, F. W.
- Title
- U.S. Navy Halon 1211 Replacement Program: Assessment of Aircraft Collateral Damage From Dry Chemical Fire Extinguishing Agents. Interim Report: 1998-1999.
- Coporate
- Naval Research Laboratory, Washington, DC
Hughes Associates, Inc., Baltimore, MD
- Report
-
NRL/MR/6180-99-8417,
November 15, 1999,
72 p.
- Keywords
-
halon alternatives
|
halon 1211
|
airframes
|
damage
|
dry chemicals
|
fire extinguishing agents
|
corrosion
|
purple K
|
potassium bicarbonate
|
sodium bicarbonate
|
fire fighting
- Identifiers
- collateral damage
- Abstract
- A literature survey and analysis (qualitative analysis) was performed of the potential collateral damage of typical aircraft materials caused by bicarbonate-based fire extinguishing agents. Very little data were found in the open literature assessing the corrosion, materials compatibility or other potential collateral damage effects caused by these agents. These data mainly address the typical storage and distribution system materials and do not address the necessary range of issues required to assess all potential aircraft exposures. In order to project the potential collateral damage, the general corrosion behavior and data for typical aviation alloys were used to supplement the limited specific data available. The general analysis indicated that significant collateral damage potential exists for airframes, structures and engines. While it is more likely that significant damage would result from a long-term exposure, potentially catastrophic short-term corrosion issues are also indicated. Increased corrosion rates are indicated for aluminum and magnesium based on the pH of bicarbonate agents and their breakdown products. The potential for turbine component damage is indicated from high temperature corrosion and through overheating caused by physical clogging of cooling holes. Previous efforts under the U.S. Navy Halon 1211 (CF3Br) Replacement Program developed operational requirements for flight deck and hangar deck (and flight line) fire fighting systems. The operational requirements for fire extinguishing systems on the flight deck and hangar deck may be defined into two main cases. The first case is for engine and electrical fires where the need to minimize collateral damage caused by the firefighting agent is high. These tires are termed small fires and are defined by the collateral damage requirements. The second case is for engine, electrical and catastrophic event (i.e., crash) fires where the need to extinguish the fire quickly outweighs any concerns of collateral damage caused by the agent. These fires are termed large tires and are defined by the lack of collateral damage concerns. For general aviation firefighting needs, the requirements may be summarized as follows: Small Class A fires, Small Class B 2-dimensional, 3-dimensional and hidden, deep-seated fires, Small Class C fires with Class A and/or Class B fuels, Large Class B 2-dimensional, 3-dimensional and hidden, deep-seated fires. The two main firefighting requirements that need to be assessed for potential Halon 1211 replacements are fire extinguishing effectiveness and collateral damage. It is expected that the currently fielded systems utilizing the primary agents Aqueous Film Forming Foam (AFFF) and water meet the requirements for large 2-dimensional Class B fires from both a fire extinguishment and collateral damage stand-point (i.e., lack of collateral damage requirements). Currently, Halon 1211 is used to meet the remaining firefighting requirements. It is the small engine and electrical tires (including their attendant collateral damage requirements) and the 3-dimensional and hidden, deep-seated portions of the large fires that require Halon 1211 replacement systems.