# Presentation: 637151

## Fuel Cell Flammability

**Fuel Cartridge Assessment**

- Int’l Aircraft Systems Fire Wkg Grp

- Harry Webster

- November 19, 2008

## BACKGROUND

**Fuel cells are an alternate power source used in lieu of or in conjunction with batteries to power electronic equipment.**
**Fuel cells use a hydrocarbon fuel source to generate electrical power, with water as the byproduct**
**Fuel sources range from highly flammable to relatively inert**

## FUEL CELLS

**Definition:  An electrochemical cell in which the energy of a reaction between a fuel, such as liquid hydrogen, and an oxidant, such as liquid oxygen, is converted directly and continuously into electrical energy **
**FAA Concerns**
- In-flight use and operation
- Carry on luggage
- Checked luggage
- Bulk Shipment

## Micro Fuel Cell Fuels

**Methanol**
- Methanol is oxidized directly in the Direct Methanol Fuel Cell (DMFC) system.
- Reformed methanol fuel cells (RMFC) produce hydrogen “on demand” and consume the hydrogen immediately within the fuel cell.
**Formic Acid**
- Fuel (formic acid) concentration: < 85% wt (Not Flammable).
- Formic acid is oxidized directly in the Formic Acid Fuel.

## Micro Fuel Cell Fuels

**Borohydride**
- Direct liquid Borohydride (Class 8) is oxidized directly in the Direct Borohydride Fuel Cell (DBFC) system.
- Indirect Borohydride (Class 8 or 4.3) produce hydrogen “on demand” and consume the hydrogen immediately within the fuel cell.
**Butane**
- A Butane or a Butane/Propane mix is oxidized directly by a solid oxide fuel cell system.
**Hydrogen Stored in Metal Hydrides**
- Hydrogen gas is chemically stored in metal powder under low pressure.
- Hydrogen is produced “on demand” and consumed immediately within the fuel cell.

## FUEL CELL CARTRIDGE FLAMMABILITY TESTS

**The fuel cell industry has made available a number of different types of fuel cell refill cartridges.  These are not complete fuel cells, but contain the fuel used to power the cells**
**Tests were conducted in the same 64 cubic foot test chamber used to test lithium batteries and the same low level alcohol fire exposure.**

## 64 CUBIC FOOT TEST CHAMBER

## TEST ARTICLE

**Medis 24/7 Power Pack**
- This is a complete fuel cell
**Fuel Type:**
- Sodium/potassium borohydride
- Potassium hydroxide
- Water
**Shipping Class**
- Class 8
**Plastic enclosure**

## MEDIS FUEL CELL

## MEDIS FLAMMABILITY RESULTS

**Plastic case is flammable**
**Unit vented some material which added to the fire**
**No explosion or rapid burning**
**Easily extinguished with Halon 1211**

## ULTRACELL

## TEST ARTICLE

**Ultracell**
- Fuel cartridge
**250 CC**
- 67% methanol
- 33% water
**Shipping Class**
- Class 3
**Metal fuel enclosure, plastic mounting**

## ULTRACELL FLAMMABILITY RESULTS

**The contents vented through end fitting after approximately 3.5 minutes of fire exposure**
**The vented material was flammable, burned with a reddish flame.**
**Plastic parts flammable.**
**Easily extinguished with Halon 1211**

## Protonex C720 Fuel Cartridge

## TEST ARTICLE

**Protonex C720 **
- Fuel Cartridge
**Fuel Type**
- Sodium Borohydride
- Sodium Hydroxide
**Shipping Class**
- Class 8
**Plastic enclosure**

## PROTONEX FLAMMABILITY RESULTS

**Vented non-flammable fumes**
**Plastic case was penetrated**
**At 7:00, small flame visible on side of unit**
**Fume buildup extinguished the alcohol fire at 11:00 minutes**
**At 12:00, small flame self extinguished**
**White paste oozed from cracked plastic case**
**15:00 No visible flames at test termination**

## JADOO POWER SYSTEMS TYPE C5

## TEST ARTICLE

**Jadoo Power Systems, Type C5**
- Fuel cartridge
**Fuel Type**
- Hydrogen in a metal hydride
**Shipping Class**
- Class 2.1
**Metal enclosure**

## JADOO FLAMMABILITY RESULTS

**At 9:30, vented gas from end cap fitting**
- Relatively large reddish blow torch type flame
- Flame gradually diminished in pressure and size
**At 15:00 test was terminated**
**Halon 1211 easily extinguished remaining flame**
**Metal enclosure not penetrated except at end fitting**

## TEKION

## TEST ARTICLE

**Tekion Inc.**
- Fuel Cartridge
**Fuel Type**
- Formic Acid
**Shipping Class**
-  Class 8
**Plastic enclosure**

## TEKION FLAMMABILITY RESULTS

**At 1:00, sprayed liquid from the fill port, 2-3’ stream**
**Liquid did not ignite**
**Plastic case deformed, but did not burn**
**Case was not penetrated except at the fill port**

## ANGSTROM

## TEST ARTICLE

**Angstrom Softank **
- Fuel cartridge
**Fuel Type**
- Hydrogen in a metal matrix
**Shipping Class**
- Class 2.1
**Plastic enclosure**

## ANGSTROM FLAMMABILITY RESULTS

**At 1:30, edges glowed red**
**Red glow continued for 4 minutes**
**Plastic case charred but did not burn with an open flame**

## LILLIPUTIAN SYSTEMS

## TEST ARTICLE

**Butane**
- Fuel cartridge
**Fuel Type**
- Butane
**Shipping Class**
- Class 2.1
**Plastic enclosure**

## LILLIPUTIAN FLAMMABILITY TEST RESULTS

**At 0:45, contents of container released and ignited**
**Entire test enclosure filled with fire**
**Fire duration: 20 seconds**

## Millennium Cell

**Fuel Type**
- Loose chemical mixture
- Sodium Hydroxide / Sodium Borohydride
**Shipping Class**
- Class 8
**Enclosure**
- Placed in 2” metal pipe cap

## Millennium Cell Flammability Results

**0:32, Ignited with small flame on surface**
**12:00, flame momentarily  extinguished with halon 1211**
**15:00 material reignited, pipe cap extremely hot**
**Material allowed to self extinguish, pipe cap cooled after 2 hours**

## Interim Conclusions

**All of the technologies present some fire hazard**
**The flammable liquids and gases are easily controlled by normally available hand held fire extinguishers**
**The corrosives (class 8) are flammable solids that are not easily ignited**
- However, once ignited, difficult to extinguish and require specialized metals extinguishers

**Additional Work**

**Flammability tests will be conducted on the different technologies as production units become available:**
- Individual units
- Bulk shipments
- Fuel cells in use powering electronic equipment
- Fuel cells charging batteries