Yes, work the mind and prevent Alzheimer's. Well, this is doing it! A little research on foam leads me to not want use aluminum bottles (even with corrosion inhibitors). Perhaps there was no corrosion inhibitor included in your mix. Still stainless steel is better although steel looks OK. Some info and links for the rest of you. I pulled a few lines from documents to illustrate the confusion. It will take further research on my part to decide what type of extinguisher to add to the one I already have.
From the ColdFire site. But rebutted in further documents.
Unlike old-fashioned AFFF foam, Cold Fire is completely non-corrosive and has an indefinite shelf life. You can put it in a 1.5 or 2.5 gallon extinguisher, or in the water tank of your crash truck and forget about it. It will never gel, crystalize, separate or corrode the metal. RDR offers even smaller 2,3 and 4 liter fire extinguishers with fixed nozzles. It can even be used in closed loop suppression/sprinkler systems. http://www.fire-end.com/foam_types.htm
Fire fighting foams can be put into two very broad categories: Class A, and Class B. These categories correspond to the types of fuels that the foams are designed to be used on. This is very important! No matter what any salesman tells you Class A foam is not designed to put out class B fires. It looks white and bubbly, but they are chemically not compatible. Using Class A foam on flammable liquids (Class B) could extinguish the fire but lead to catastrophic results because of its inability to secure the explosive vapors. Class B fuels can be subdivided into two more subclasses: Hydrocarbons like gasoline, kerosene, and fuel oil will not mix with water; and polar solvents like alcohols, ketones, and ethers which will mix with water.
Class B foams can be divided into two general categories: synthetic based or protein based. Both types have advantages and disadvantages.
Synthetic foams are basically super soap with fire performance additives. They include high expansion foam, aqueous film forming foam (AFFF), and Alcohol Resistant aqueous film forming foam (AR-AFFF). In general synthetic foams flow more freely and provide quick knockdown with limited post fire security.
Protein foams use natural protein foamers instead of a synthetic soap, and similar fire performance components are added. Protein type foams include regular protein foam (P), fluoroprotein foam (FP), alcohol resistant fluoroprotein foam (AR-FP), film forming fluoroprotein (FFFP), and alcohol resistant film forming fluoroprotein (FFFP). In general, protein based foams spread slightly slower than synthetic, but produce a more heat resistant, longer lasting foam blanket.http://www.firehouse.com/forums/showthread.php?t=35275
Protein-based foams can offer a significant advantage over detergent-based foams, however. Under some conditions, detergent foams make certain fuels easier to ignite.
Aqueous film forming foams (AFFF) are water-based and contain corrosive chemicals.
Suitable for use with carbon steel, fiberglass, polyethylene or stainless steel.
It is intended for use at a proportioning rate of 1% (1 part AFFF concentrate to 99 parts water) on Class B hydrocarbon type fuels such as gasoline, kerosene, diesel, etc. Chemguard 1% AFFF is not intended for use on fuels, which are polar solvent/water miscible such as alcohols, ketones, esters, etc.
Full stainless steel cylinder that resists corrosion.
Protein foams include regular protein foam (P), fluoroprotein foam (FP), alcohol resistant fluoroprotein foam (AR-FP), film forming fluoroprotein (FFFP), and alcohol-resistant film forming fluoroprotein (AR-FFFP).
FFFP foam on blended gasoline is your best choice because gasoline blended with MTBE prevents AFFF from forming a film under the bubbles.http://safetyinfo.wordpress.com/fire-safety/classification-of-fire-extinguishers/water-foam-fire-extinguishers/