Lithium Battery Fire Could Burn Through a Cargo Hold

Air Safety Week,  July 26, 2004  

• E-mail
• Print
• Link

Halon extinguishing agent has no effect on fire intensity

Lithium batteries may represent the ultimate hazardous material, especially when shipped in bulk as cargo, with the potential to breach all defenses should they catch fire. That is the principal finding of a June report of lithium battery fire tests conducted by the Federal Aviation Administration (FAA) Technical Center at Atlantic City, N.J.

The extreme hazard portrayed in the report suggests that it may be time to consider restricting lithium battery shipments to cargo aircraft. Presently, lithium battery shipments require prominent labeling as hazardous cargo, and, after Jan. 1, 2005, the batteries must undergo a "battery" of tests in order to be approved for shipment. However, those tests - for altitude, vibration, shock, etc. - do not include a test for fire resistance. In a shipment of closely packed lithium batteries, should one battery catch fire, a chain reaction results. The fire spreads from battery to battery in an explosive conflagration of molten lithium, according to the Technical Center report.

The examination of lithium battery fires was undertaken after a pallet of such batteries caught fire on the ground at Los Angeles International Airport in April 1999. The pallet was inadvertently dropped onto the tarmac, and a battery fire resulted, despite there being no external ignition source. There are no confirmed reports of bulk lithium battery fires in the air, but that is precisely the reason the FAA Tech Center undertook its examination of this more dangerous scenario. There is one case where a lithium battery fire may have played a role in the crash of a transport category airplane. In November 1987 a South African Airways B747 combi (a hybrid freighter with a partition separating cargo from passengers on the main deck), with 159 passengers aboard and cargo which included a consignment of lithium watch batteries, disappeared into the Indian Ocean off Mauritius.

After a wreck survey by robot cameras and limited debris recovery, investigators determined that the lithium batteries were located in the same area that was established to have been the seat of the fire. The airplane also was carrying a cargo of ammonium perchlorate, a rocket propellant known to be unstable and capable of spontaneous ignition. As a propellant with its own oxygen, ammonium perchlorate would have rapidly promoted a fire. However, in revealing testimony to the South African Truth and Reconciliation Commission, the presence of the lithium battery shipment was mentioned, and is pertinent to what has been revealed by the FAA lithium fire tests about battery venting, explosions, and accelerated self-reactive fires. The testimony obviously was dealing with the batteries' packaging material, but the general description of the fire that doomed the plane reinforces the point that lithium batteries can be extremely dangerous if they catch fire.

Using a steel test chamber to simulate an aircraft cargo hold, the FAA tests show that a runaway fire involving a shipment of lithium batteries might well result in loss of the aircraft. The batteries involved were those used commonly in consumer electronic products (e.g., video cameras).

Batteries were tested singly, and in groups of 32, 64 and 128. Tests also involved groups of batteries packed in rows inside cardboard boxes.

For test purposes, the battery fires were started by igniting a "fire pan" filled with alcohol. The findings were fearful. To summarize:

* A relatively small fire source was sufficient to start a lithium battery fire.

* The heat from a single battery afire was sufficient to ignite adjacent batteries.

* The outer plastic coating on the batteries easily melted, fusing the batteries together, adding to the intensity of the fire.

* The chain reaction ignition continued until all batteries were consumed.

* The molten lithium burned explosively, spraying white-hot lithium to a radius of several feet as the batteries bounced around.

* The duration of the peak temperature increased with the number of batteries, reaching as high as 1,400[degrees] F (as a matter of interest, the melting temperature of aluminum is around 1,200[degrees] F).

* The cardboard packing proved highly flammable. The packing delayed battery ignition by about 30-60 seconds, but once ignited, the fire among the close-packed batteries was worse.

* While thick-wall cargo liners were able to contain the fire (barely), thin-walled fire liners proved ineffective. The battery fire ignited the resin in the liner, and the liner was completely penetrated by molten lithium.

* Halon fire-suppressing agent, injected in sufficient concentration to "knock down" a fire, proved totally ineffective, even when injected after just the first battery had caught fire. Nor did it have any effect on the peak temperature. The fire continued as if Halon were not present.

* Lithium batteries catch fire with explosive force. When they burst, they create a pressure pulse. The eight-battery test produced a pressure pulse of 1.8 psi, and the 16-battery test generated a 2.6 psi pulse.