We have all heard those words announced when the ten-second countdown begins to a rocket launch. The words came to mind recently when I looked at a curve titled "Time v. products of combustion" on the USFA web site (www.usfa.dhs.gov/downloads/pdf/coffee-break/time-vs-products-of-combustion.pdf).
The number 10 shows up prominently on the USFA curve, but it is not a countdown. Rather, it is the average number of minutes before fire units arrive at fire scenes and begin suppression. The curve also shows the short time to residential sprinkler activation. Not only do they intervene long before firefighters can get there, they act before conditions in the room of origin can become untenable to life.
The curve shows other data, including the average time to flashover. According to a report from the National Institute of Tests and Standards (NIST), that point has dropped from 17 minutes to three. Flashover is significant because conditions in a home quickly deteriorate when flashover occurs. However, conditions in the room of origin become untenable to life halfway to flashover. What that means is that anyone in the room of origin has about a minute and a half to get out before there is too little oxygen or it is too hot to take a breath.
Residential sprinklers usually operate in less than a minute, which is why they are such effective life safety devices. Even the fastest, most heavily staffed, fire department cannot get to a fire in time to save lives in that amount of time. That is why I tell fire chiefs, "Adding more stations and firefighters will not affect your record of life loss. If you want to do that, get sprinklers installed."
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