Source: Lotus West
Author: Jim Kerswell
Title: FIRE EXTINGUISHERS
Several weeks ago I decided to buy a Fire extinguisher for my Elan, after noticing them in friends' cars and realizing that they are now required equipment for some classes of racing. Since I spent about a week researching the subject, I thought I might pass on some of what I found. This might be the incentive some people would need to get an extinguisher. I don't know how easily fiberglass bodies burn. I have no desire to learn from first hand experience. But even if one never has to use or on one's own car, someone else's car might be saved by having an extinguisher.
The main rating agency for fire extinguishers is the Underwriters Laboratory. Extinguishers are rated as to the kind of fire they are effective against, and on an ascending numerical scale within those categories. Category "A" fires are those fueled by wood, paper and textiles. "B" covers flammable liquid and grease fries, while electrically live fires are Category "C". Most of the home and automotive fire extinguishers which one typically encounters are ineffective for Category "A" fires. However, for automotive use we are concerned with the last two categories, obviously.
The types of extinguisher for on board automotive use contain either a foam or a dry chemical expellant. The dry chemical extinguisher seems the more prevalent. Its popularity is perhaps due to the ease in cleanup after its use. However, U.L. does recognize the foam extinguisher as being somewhat effective against Category "A" fires, while the dry chemicals are not. Within the dry chemicals there are two different types, sodium bicarbonate and potassium bicarbonate. Potassium compound is known in the trade as "Purple K". The important thing to remember about it is that it rates about a third more effective than the sodium chemical. It is, consequently, more expensive.
There are two common sizes of extinguishers: 2-3/4 lb. and 5 lb. The "weight" being that of the chemical. The smaller size is the one most commonly seen. I saw an extinguisher even smaller being sold at Akron and rated 2-B,C. I would caution against the purchase of such an article unless one wants an extinguisher merely For psychological reasons. A man in the business of selling fire extinguishing systems strongly recommend the 5 lb. unit, remarking that the duration of the smaller size was too short, however, the larger unit may be too bulky for attachment, in a readily accessible spot in a small car. As cost will inevitably be a factor, it should be mentioned that the 5 lb. units run from $22 to $32, depending on type of chemical and source. A man at the General Fire Extinguisher factory pointed out that if the conflagration has reached such an extent that a 2-3/4 lb. extinguisher won't put it out, the larger size probably won't either.
I finally decided to buy a "Purple K" extinguisher. This is sold in a 2-1/2 lb. size, although the physical dimensions are identical to the 2-3/4 lb. size. The unit is U.L. rated at 10-B,C as compared to the 5 to 8-B,C rating of the same size sodium bicarbonate extinguishers. cost about $17.00. As the more expensive "Purple K" extinguishers are not normally sold at auto parts stores or discount houses. I bought mine at the General Fire Extinguisher Factory.
A word of caution on mounting. Although you will want the fire extinguisher where you can get at it if you ever have to use it, those driving roadsters are advised not to put them where they are easily seen from the outside. The quick release makes them easy to steal.