The following scenario was recently presented to me: A sleepy father finally gets his fussy baby to sleep when a smoke detector, possibly sensing steam from an over-heated bottle of formula, blares a needless, high-pitched alarm. The baby – and the mother (up to that second grateful the father had given her a much-needed break) are now both awake. At least one is screaming. It takes a while, but the baby is finally fed and falls asleep. The father, to prevent his baby from being woken again, removes the batteries from the smoke detector, leaving his home – and his family – without an early warning system for smoke. According to industry sources, between 17% to 23% of fire-related deaths (during time frames in the 2010s) occurred in places where a smoke alarm was present but either disabled or non-fuctioning*. A chill went down my spine because my colleague could have been talking about me and my daughter twenty years ago. (While I can tell you that eventually I reloaded batteries into the smoke detector I won’t say - in case either my wife or daughter read this blog - how long it took me to do so.)

As I described in my previous blog, Smoke Sensor in a Bottle Cap, ADI has developed an advanced smoke detection hardware platform (the ADPD188BI) which is able to “see” characteristics of smoke. These characteristics, also called profiles, include the speed and rate smoke collects along with its density at various times after initial detection. The goal is for the smoke detector to blare an alarm only when the smoke’s profile indicates a fire. The more confidence consumers (such as this lunkhead father) have in their smoke detectors means more detectors keep their batteries and do their job, reducing deaths and injury. But here’s the rub: the smoke detector cannot, by itself, distinguish different types of smoke, it only “sees” the smoke. To make the platform a reliable smoke detector, it needs to be ”trained” to know the differences.

ADI worked with Underwriter Laboratories (known by most of us from the letters UL, they have been certifying merchandise for product safety since 1894), Intertek (another prominent testing service) and the Occupational Safety and Health Administration (OSHA). The goal was to develop a solution to meet the latest smoke/flame detection standard, officially known as UL-217 (8th edition.) Gathered at one of the UL’s testing centers, we started to burn stuff. Paper. Wood. We make Polyurethane smoke. We made it flame. Cooking grease was heated. A dozen times. A hundred times. Ultimately, these and other substances were burned over one thousand times. Above them all, in a specially built chamber, our smoke detection platform was hung and collected data on each event.

 

From all those data points patterns emerged for each tested substance. The collected data was then fed into a sophisticated data analysis tool to find patterns, and from those patterns ADI developed an algorithm – available now as part of a new reference design from Analog Devices – one which removes the risk of an errant alarm from the platform. Developers of smoke detection solutions for the market can avail themselves of any of these levels of design support:

  • Hardware only, it includes the previously mentioned ADPD188BI smoke detection platform, a programmable microcontroller with a pre-installed smoke detection algorithm which was developed using those thousands of smoke tests we talked about earlier.
  • Data from the smoke tests. ADI provides all the data collected during the UL tests, from which developers can write their own algorithm.
  • The Algorithm. For developers looking to rapidly prototype their products, ADI offers the original source code, complete dataset from the tests, plus the final algorithm - the one which has already been verified as UL-217 (8th edition) – compliant.

With the CN0537 Smoke Detector Reference Design Analog Devices provides developers with all the tools they need – both hardware and software – for rapid prototyping of smoke and flame detection products which meet the most up-to-date stringent requirements. Fathers of fussy babies everywhere say “thank you.”

 

#30#

 

* SOURCES

Smoke Alarms in U.S. Home Fires, March 2014

Smoke Alarms in U.S. Home Fires, January 2019

Both reports authored by Marty Ahrens for the National Fire Protection Association

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