Fire sprinkler systems save lives, but those containing too much antifreeze can actually fuel flames or even cause a flash fire explosion, the CALL7 Investigators have learned.It happened in Truckee, Calif., on Aug. 18th 2009, according to a Fire & Explosion Investigation Report obtained by 7NEWS.Isela Minutti, 27, was killed and her husband, 30-year-old Wuliber Martinez, was severely burned over 40 percent of his body.According to the report, Minutti had given birth to the couple's third child 10 days earlier.Her husband was frying onions over an electric stove when the pan caught fire, the report explained, saying, "As he turned (180-degrees) to the kitchen sink with the flaming frying pan to put water on the fire and the fire sprinkler activated directly over him and upon activation a violent explosion resulted."The blast was so strong that window glass was blown 86 feet from the building and an interior door frame and attached door were "pulled approximately 3-inches from the frame," the report reads.Investigators determined that Minutti was 5 to 7 feet from the initial sprinkler that had activated and "the resulting burns/explosion caused her death."Tests of the sprinkler system determined there was more than 70 percent antifreeze, specifically glycerin, and about 30 percent water in the pipes.CALL7 Investigator John Ferrugia discovered the flash fire explosion in Truckee was not the first time this had happened, but, it did get the attention of the National Fire Protection Association.The NFPA Standards Council sets national codes and guidelines for fire protection and safety in the U.S.In the months following the Truckee explosion, the NFPA issued a safety alert, reading, "Existing residential sprinkler systems whenever possible should not contain antifreeze solution."If antifreeze is necessary to protect the pipes from temperature fluctuations, the NFPA recommends it be the lowest possible concentration.Since that initial alert, the NFPA has conducted further tests and is continuing to update its guidelines.With the help of the engineering consulting firm Advanced Engineering Investigations, 7NEWS conducted a test at the Metro Fire Training Center in Littleton."Today we have mixed a solution of 60 percent glycerin and 40 percent water," explained fire suppression consultant Charlie Sullivan. "That will get you to minus 47.3 degrees Fahrenheit. You'll see that commonly in the mountains."For the first test, we set up a stove and hot skillet with a small amount of oil to simulate frying food. The oil caught fire and the overhead sprinkler was activated.The flames grew rapidly as the spray from the sprinkler hit the hot surface. The sprinkler also coated the test center's concrete walls in glycerin. That's important to note, because home kitchens do not typically have concrete walls, but instead drywall or tile. Also, home kitchens typically contain wood cupboards, curtains, hand towels and even wallpaper or cleaning supplies."Essentially, it looked like it fed the flame. It could also be the grease, so the next thing we're going to do is a hot pan, no oil," Sullivan explained to Ferrugia.The second test produced the same result.That is important because, as mentioned before, the Truckee fire was not the first time a sprinkler system had caused a flash fire.On Oct. 28th 2001, an overhead heater on the outside deck of the WINDANSEA restaurant in Highlands, N.J., became so hot, it triggered the sprinkler system.When the antifreeze mixture (propylene glycol) hit the hot surface of the heater, it sent a ball of fire through the enclosed deck.Nineteen people were injured; one was severely burned.The fire marshal's report reads, "The vapors from the sprayed liquid mixture ignited and a flash fire occurred."The fireball... melted a canvas and plastic enclosure wall on the exterior of the deck. When this occurred it allowed the outside air currents to reverse the travel of the fire ball and it extended into the inside of the restaurant.""The implications are the fire is going to get bigger and get bigger quicker," said Littleton Fire Training Chief, Jay Ruoff.Ruoff watched the 7NEWS test at the Metro Fire Training Center."I was surprised," said Ruoff after watching the fire expand and climb."Never seen it before?" asked Ferrugia."I have never seen that before," said Ruoff. "I don't think that anybody has a good handle on where the glycerin systems are.""So, you've got to find out?" asked Ferrugia."I think we've got to find out, and I'm not sure how we do it," replied Ruoff.