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Areas of Expertise

Michael Fox, PhD.



Pool Chemicals Fire

Chemaxx was hired to investigate pool chemicals believed to have been responsible for a sudden, unexpected vigorous fire. The tragic incident took place inside the rear of an SUV that was traveling with two parents in the front and three children in the back seat. It is believed that an aerosol product leaked an organic solvent that made contact with the pool chemicals. The mixture burst into flames that instantly engulfed the entire vehicle in flames. While the parents were just able to exit the vehicle they were not able to rescue all their children even though they received severe burns trying. Only one child was saved and two children perished in the fire. It just doesn't get any more horrific than this.

pool chemical caused fire

The specific nature of the pool chemical is calcium hypochlorite, or Ca(OCl)2. Different pool products contain varying amounts of Ca(OCl)2.

Chemaxx conducted experiments in which a small amount of flammable liquid was added to different pool products. In general, the products with the highest percentage of Ca(OCl)2 burst into flames the fastest and the strongest, as shown in Video 1.

Video 1- Press play button (38 seconds)

The unexpected part was the lack of early warning, such as smoke. For example, a thermocouple placed in the container of pool product showed little to no increase until the sample burst into flames, as seen in Figure A.

Figure A - Temperature vs. Time for High Ca(OCl)2 Pool Chemical

The dangerous nature of the high percentage Ca(OCl)2 pool products stands in sharp contrast to pool products with less Ca(OCl)2 plus other ingredients. When these low Ca(OCl)2 products are mixed with a small amount of flammable liquid, they eventually react but produce only smoke and do not burst into any flames, as seen in Video 2.

Video 2- Press play button
(Allow up to 3-4 minutes to download with slow
connection- Video length: 4 min. 28 Seconds)

Likewise, the temperature of the sample remains low compared to the higher
Ca(OCl)2 products, as seen in Figure B.

Figure B - Temperature vs. Time for Low Ca(OCl)2 Pool Chemical

The lessons learned are many. For the manufacturers of pool chemicals the lesson is that Ca(OCl)2 based products can be made safer by lowering Ca(OCl)2 percentages and label warnings need to be more prominent. Packaging should ensure that the leakage of Ca(OCl)2 powder does not occur. For example, the identical Ca(OCl)2 pool chemicals are sold in Europe in solid plastic containers while being sold in the US in less sturdy plastic bags prone to leakage. For consumers the lesson is to be extremely careful about the storage and use of Ca(OCl)2 based pool chemicals. They should be kept separated in vented metal containers and kept safely away from children and any combustible materials.

Additional scientific research was conducted in conjunction with this project that included thermal gravimetric analysis (TGA), conventional chemical analysis and packaging considerations. There are also plans to do differential scanning calorimetry (DSC).

Dr. Fox has his Ph.D. in Physical Chemistry and is a Certified Fire & Explosion Investigator with substantial experience investigating complex industrial chemical accidents, fires and explosions as well as chemical-related consumer product accidents, fires and explosions.