There are many types of commercially available fire extinguishing agents used for a wide range of applications. The specific extinguishing agent used for a given application depends on the fire threat and design criteria. For class-C cargo compartments on aircraft, a gaseous flooding agent is used. Halon 1301 is currently the sole extinguishing agent being used in class-C aircraft cargo compartments. It requires a replacement due to its harm to the environment.

The fire threat within cargo compartments is changing compared to the threat that existed when aircraft class-C cargo compartment requirements were first established. The quantity of lithium batteries being shipped in cargo compartments is increasing each year. Lithium batteries can spontaneously catch fire or undergo thermal runaway where they release a significant quantity of flammable gas composed of hydrogen, carbon monoxide and hydrocarbons.

The objective of this study was to evaluate the effectiveness of Halon 1301 and some of its potential replacements against several flammable gases including lithium battery thermal runaway gases.

The United Nations (UN) Subcommittee of Experts on the Transport of Dangerous Goods (SCOE TDG) approves proper shipping names (PSN) and assigns each PSN with a four-digit UN number. Currently, two UN numbers have been assigned to lithium batteries as either UN 3480, Lithium ion batteries (including lithium ion polymer batteries) or UN 3090, Lithium metal batteries (including lithium alloy batteries). This research seeks to support the UN SCOE TDG establish a more performancebased approach to classifying the various types of lithium-ion batteries for transportation. Performance based classifications will support a better understanding of the risks of transporting lithium batteries and promote the industry in further developing safer batteries. A proposed standardized test method was used to assess the combustion hazard from a lithium-ion battery that has undergone thermal runaway. Lithium cobalt oxide pouch cells (3.7 V, 4.8 Ah) and cylindrical cells (3.7 V, 2.6 Ah) were tested at various states of charge (SOCs) and heating rates. The cells were individually heated to induce thermal runaway inside of a pressure vessel, resulting in a venting of gases. The vent gases were analyzed for their constituent’s volume, overall gas volume, and combustion energy. Key findings are as follows:

• The vent gas volume and combustion energy increased linearly with SOC for the pouch and cylindrical cells.
• The top three constituents as a percentage of the vent gas by volume across all SOCs and heating rates for the pouch and cylindrical cells were carbon dioxide, hydrogen, and carbon monoxide
• The vent gas volume and combustion energy increased with the heating rate for the pouch and cylindrical cells.
• When comparing cells heated at 20°C/min to cells heated at 5°C/min, across the tested SOCs, the pouch cells released an average of 14.1% more vent gas and had an average of 34.4% greater combustion energy, the cylindrical released an average of 7.2% more vent gas and had an average of 13.0% greater combustion energy.

Lithium batteries have been shipped aboard aircraft with existing United Nations (UN) classification numbers for many years. Although the UN classifies lithium batteries as dangerous goods, current UN numbers for lithium batteries do not indicate what level of hazard each individual shipment may pose. Lithium batteries can exhibit varied temperature rise and propagation characteristics when heated to thermal runaway. Therefore, This study was conducted to characterize the propagation of cylindrical cells and pouch cells at various states-of-charge (SoCs) to determine or verify key test factors that should be considered for development of a lithium battery propagation test.

Six cells were placed in line with each other (denoted cell # 1 through cell #6) in an insulated box, and thermal runaway was initiated in cell #1. Once thermal runaway initiated, power to the heater was cut off and propagation characteristics were recorded. Key findings included:

• The onset temperature of thermal runaway for the pouch cells depended on SoC. For example: A test at 20% SoC showed a thermal runaway onset temperature 53 °C to 83 °C higher than tests at 100% SoC.
• Pouch cells propagated faster than cylindrical cells.
• In the test at 20% SoC, the temperature of pouch cell #6 was as high as 108°C when pouch cell #1 went into thermal runaway and in the test at 100% SoC, pouch cell #6 was only 36.5 °C when pouch cell #1 went into thermal runaway. In other words, at a fixed heat rate, more time was required for cells at a lower SoC to enter thermal runaway. This indicated the need for more than six cells because too much heat was transferred to the system before propagation began.
• It was observed that the mass loss of each individual cell was fairly constant with slightly higher mass loss in the first cell.
• Cell voltage was a usable metric to pinpoint thermal runaway in the pouch cells but behaved erratically in the cylindrical

Knowing fire temperature and soot concentration in a fire is very important in fire safety research. The fire radiant energy, a function of fire temperature and soot concentration, contributes about 40% of energy loss to the walls of the Ohio State University (OSU) fire calorimeter during the burning of large area cabin materials. This report presents a method to measure the full field of flame temperature and soot volume fraction in fire using a digital camera. The report also outlines a new procedure to simultaneously calibrate and characterize the camera’s detector using a blackbody furnace. The developed methods are implemented to measure flame temperature and soot volume fraction in a liquid-fueled steady laminar diffusion flame, impacted by the phosphorus type flame-retardant material. The flame-retardant material is found to promote soot formation and suppress soot oxidation in the fire. The increased net soot concentration cools the flame, resulting in incomplete combustion.

Hidden fire in an aircraft overhead inaccessible-area is hazardous to in-flight safety and could lead to catastrophic disaster. In this case, fire detection at the earliest stage requires an improved understanding of the heat and mass transfer in overhead areas with curved fuselage sections. In this effort, an experimental campaign was conducted at the FAA William J. Hughes Technical Center on different fire scenarios for the Boeing747-SP overhead inaccessible-area to advance knowledge on this phenomenon and provide validation data for the Fire Dynamics Simulator (FDS). Extensive work has been done recently to enable computer simulation of fire on complex geometries within this tool. Therefore, we use the experimental data obtained to perform validation of said capability. Model validation results are defined in terms of thermocouple readings measured and computed with satisfactory overall agreement.