Where there’s smoke, there’s fire. Where there’s steam, there’s just hot water. Yet steam can trigger false alarms from smoke detectors, and it’s one of the latest sources of so-called nuisance alarms that smoke-alarm manufacturers are trying to reduce.
Addressing nuisance alarms represents one of the many baby steps that manufacturers have taken in the past 4 years to improve their home-safety products. For example, a new combination smoke/carbon monoxide (CO) alarm is the first such model that also detects natural gas, which means that you won’t have to buy a separate alarm that will alert you to a natural-gas leak. A series of smoke-alarm, CO-alarm and combination smoke/CO-alarm models has a built-in relay switch that makes it easier to connect the alarms to lights, so the lights turn on when the alarm goes off. Finally, the first fire extinguisher that’s designed specifically to be used on range-top cooking fires arrived last year, but it isn’t recommended for use on other types of small residential fires.
FALSE ALARMS. Smoke-alarm manufacturers in recent years have tackled all sorts of nuisance-alarm sources, such as cooking smoke. They accomplish this by adding so-called smart chips to their models. These advanced microprocessors are designed to deliver more-sensitive smoke-detection capabilities.
All smoke alarms measure the amount of smoke that reaches the alarm, so when the smoke gets too thick, the alarm goes off. But in April 2010, Universal Security Instruments (USI) introduced three smoke alarms and a combination smoke/CO alarm that use a microprocessor that also determines the rate at which the smoke that reaches the alarm increases or decreases. That capability helps the alarm to do a better job of distinguishing false alarms from emergencies, says Ron Lazarus of USI.
For instance, if you open an oven door and a burst of steam finds its way to a typical smoke alarm, the alarm will go off. But Lazarus says the microprocessor that’s on the four USI models waits a millisecond to detect if the rate of steam increases. If the rate of steam doesn’t increase, the smoke alarm waits another millisecond, detects the decrease in steam, registers it as a false alarm and stays silent. But if smoke that enters the alarm increases after a millisecond, the alarm sounds. You’ll pay at least $30 for a model that has this or similar technology.
The problem with the approach to nuisance-alarm reduction by USI and all other manufacturers is that no industry standard exists, says Thomas Cleary, who is a fire-safety research engineer at National Institute of Standards and Technology. He believes that smoke alarms that are designed to reduce the frequency of nuisance alarms generally do what the manufacturers say they do. But the lack of a standard means that nobody has a way to tell whether the USI approach does a better job of reducing the occurrence of nuisance alarms than do models that are from other manufacturers (First Alert and Kidde).
Cleary says scientists are working on creating such a standard, but it likely will be more than a year before guidelines are in place. For now, you should know that Underwriters Laboratories ratings on models that are designed to reduce the frequency of nuisance alarms pertain only to smoke detection; they don’t assess a model’s capability of reducing nuisance alarms.
SENSING CHANGE. USI’s new models also are the first that combine ionization and photoelectric detection technology on a single sensor. USI calls this IoPhic sensor technology. Other smoke alarms that use both ionization and photoelectric technologies have separate sensors for each. (Ionization sensors are designed to respond to fires that flame fast; photoelectric sensors are designed to respond to slow, smoldering fires.)
USI says having one sensor that uses both technologies makes the sensor less prone to false alarms than are models that have two sensors. But independent experts whom we interviewed say having ionization and photoelectric technology on a single sensor provides no benefit when compared with having those technologies on separate sensors.