Super Sensors Help Save Lives
Where there’s fire, there’s smoke. According to the Centers for Disease Control and Prevention, more fire victims die from smoke and toxic gases than from burns.
The most important part of installing any smoke detector is understanding why it is necessary in the first place and why it should be placed in a certain location. There is no doubt smoke detectors save lives, but that is a fact far too many people take for granted.
Residential smoke detection installations rose astronomically following pivotal research conducted in the 1970s. This research provided a key understanding of how smoke detectors save lives in real-life circumstances. Although residential conditions have changed significantly since then, many of the findings from this period have remained relevant.
As part of SECURITY SALES & INTEGRATION‘s 30th anniversary, we’ll explore how this research, and an updated version of it, is shaping the new generation of detection technologies and giving installing fire system providers the tools to sustain their business.
Landmark Research Still Telling
The Detector Sensitivity and Siting Requirements for Dwellings, known as the Indiana Dunes (Dunes I) research study, remains a benchmark in fire/life-safety research. The study was conducted from 1974 to 1976 for the National Institute of Standards and Technology (NIST) under contract with the Illinois Institute of Technology Research Institute and Underwriters Laboratories (UL). It focused on the placement and sensitivity requirements of smoke detectors in residential homes that were scheduled for demolition as part of an expansion of the Indiana Dunes National Lakeshore Park in northwest Indiana.
Researchers selected readily available detectors and installed them in homes to measure their performance during a fire. Residences with contents manufactured in the 1960s and early 1970s were set afire and used as test beds. Each of the test rooms was instrumented so that conditions such as temperature and smoke obscuration were continually monitored. Test fires were ignited to judge when unassisted escape to safety (but not jumping out windows) would no longer be practical.
The report presented results in a unique way. It defined adequate lifesaving potential by the amount of time people in a household would need to escape using the “primary escape path,” which was defined as the path from any room to one of the exterior doors. The escape time was measured from when the detector went into alarm until a room’s condition reached one of the defined tenability limits (e.g. smoke optical density, temperature or carbon monoxide concentration).
This was the first test that evaluated detection performance based on the amount of escape time that started upon detector actuation. These escape times populated a probability plot showing the percent of experiments that met or exceeded specific minimum escape times. Results for safe escapes were determined by selecting a minimum escape time and then selecting the percent of cases in which that time was available. Based on the test results, smoke detection on every level of a home provided adequate escape time in roughly 90 percent of the fires.
Installing smoke detectors on every floor level of the home yields optimum performance because it is impossible to predict where a fire might start. The closer a smoke detector is to the fire, the faster it will respond, allowing more time for residents to escape. For example, walls, stairs and HVAC systems, especially air conditioning, can impede smoke propagation to a detector. Therefore, coverage on all levels is imperative.
The results of the Dunes I test established the sensitivity limits for the Single and Multiple Station Smoke Alarms standard UL 217, which is utilized for residential applications. The same smoke obscuration limits of 0.5 percent to 10 percent were subsequently adopted into Smoke Detectors for Fire Alarm Signaling Systems standard UL 268, applicable to commercial buildings.
Synthetics and Smoke Detection
Modern construction materials are changing the composition of typical residential environments. Most homes today contain fewer natural materials and more synthetic fabrics than they did 30 years ago. There is less cotton, linen and silk, and more nylon, polyester and acrylic. That changes the way fires burn and the types of smoke they generate.
Thirty years after the Dunes I research, some members of the industry and the fire services administration community questioned whether the data would change when synthetic materials were used with current smoke detector technologies.
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