CHICAGO, Ill. – The nature of smoke and fire isn’t normally a hot topic of discussion for campus safety and security professionals. But according to the experts who participated in the Underwriters Laboratories (UL) Smoke Characterization Seminar, which took place in Lombard, Ill., Nov. 14 and 15, that subject, along with the proper installation of smoke detectors, should be a key consideration for fire installations.
The very makeup of what burns in a fire has evolved through the years, says J. Thomas Chapin, UL Corporate Fellow and Director of R&D. “The ‘fuel’ that surrounds us is changing – that is, the contents and construction materials in our homes and offices. That material dictates fire growth, including its ignition, decomposition, flame spread and smoke generation,” he claims. “We see a continuing shift from natural to synthetic materials in the products we purchase and use every day.” Therefore, what is in a room – whether it be telecommunications cables, hospital or dorm mattresses, furniture or cooking oil – can affect how smoke detection technologies respond. Indeed, ionization and photoelectric alarm responsiveness depends on the smoke’s particle size distribution and count, which is influenced by the chemistry of the fuel that is burning.
Whether a material bursts into flames or smolders also affects smoke detector performance. For example, liquids typically do not smolder, while solids will smolder and then flame. When UL compared ionization and photoelectric alarms, in situations where flames were present, ionization detectors generally worked better – on average they triggered 78 seconds earlier. In non-flaming (also called smoldering) tests, however, photoelectric alarms triggered 75 seconds earlier.
Slow, low energy fires are also challenging to traditional passive alarms for several reasons: These fires may not push smoke to the ceiling, there may be static air and the smoke may settle. All of these factors can prevent a smoke detector from activating.
So what types of smoke detectors should actually be installed? According to Paul Patty, senior research engineer for UL, both types are effective if they are installed per the manufacturer’s instructions and the minimum requirements of NFPA 72. “Deviating from these two simple steps can cause you to lose the benefit of early warning from your fire alarm system,” he says. Still, knowing what is in a room, including its chemical make-up, can lead campus officials to select the most appropriate smoke detection equipment for the situation at hand.
Other ways campuses can reduce the risk of death from residential fires is to decrease the flammability of a room’s contents, as well as the quantity of contents in a room, which reduces the amount of fuel available to burn. Being more aware of the sources of ignition (for example, cigarettes, candles, heating equipment and defective electrical equipment) is also extremely important. The three key factors that play a role in fire safety are: a) sources of ignition, b) fuel and c) human behavior.
As far as human behavior is concerned, manufacturers and testing laboratories like UL are exploring ways to improve how people respond to smoke detectors. Since not everyone, such as children, the hearing impaired and college students, are capable of hearing these alarms, research is currently being conducted to see if these individuals will better respond to light, different sounds, voice or vibration. Earlier alarm activation and expanded alarm responsiveness are also being explored.
Additional information on UL research can be found online at www.ul.com.
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Proper Installation Makes a Difference
According to NFPA 72, chapter 5, when installing smoke initiating devices, the following should be taken into account:
- Ceiling shape and surface
- Ceiling height
- Configuration of contents in the protected area
- Combustion characteristics and probable equivalence ratio of the anticipated fires involving the fuel loads within the protected area
- Compartment ventilation
- Ambient temperature, pressure, altitude, humidity and atmosphere
