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Thermodynamic Properties of Alternative Agents.


pdf icon Thermodynamic Properties of Alternative Agents. (977 K)
Yang, J. C.; Breuel, B. D.

NIST SP 861; April 1994.

Evaluation of Alternative In-Flight Fire Suppressants for Full-Scale Testing in Simulated Aircraft Engine Nacelles and Dry Bays. Section 2, Grosshandler, W. L.; Gann, R. G.; Pitts, W. M., Editor(s)(s), 13-35 pp, 1994.

Available from:

Government Printing Office
Order number: SN003-003-03268-9

Keywords:

halons; thermodynamic properties; halon 1301; solubility; fire extinguishing agents

Abstract:

Depending upon their applications, current halon 1301 (CF3Br) bottles are normally filled to about half of the bottle volume, and the bottle is then pressurized with nitrogen to 4.1 MPa (600 psig) at room temperature. The purpose of using the pressurization gas is to expedite the discharge of the agent and to increase the penetration distance of the agent during discharge. However, this driving force, i.e., the total pressure in the bottle, will vary depending on the ambient temperature because the vapor pressure of the agent and the solubility of the pressurization gas in the liquid agent vary with temperature. The current military specification (MIL-C-22284A) for halon 1301 containers stipulates that the container should have a proof pressure of 9.62 MPa (1400 psig), a burst pressure of 12.37 MPa (1800 psig), and a frangible disc that will rupture at a pressure between 8.59 MPa (1250 psig) and 9.62 MPa (1400 psig) at 70 deg C. In order to explore the possibility of using existing halon 1301 bottles for "drop-in" replacement agents or to provide safety guidelines on bottle design for the alternative agents, two important tasks are to determine (1) the solubility of the pressurization gas in the liquid agent and (2) the final pressure of the vessel when exposed to different ambient temperatures.