Types of Smoke Alarms

Many homeowners and apartment dwellers have installed smoke alarms, but few understand how these devices work. The first consideration is what type of smoke alarm you currently have or are thinking of purchasing. There are two primary types of smoke alarms, and you will be deciding between photoelectric vs. ionization.

While you might never have realized there are two types of smoke detectors, let alone the differences between them, understanding how each of these works could someday save your life. Here is what you ought to know:

What is an ionization smoke and fire alarm?

About nine out of every ten smoke alarms are ionization alarms. These smoke detectors have an ionization chamber in which a small amount of radioactive material is placed between two electrically charged plates. As smoke enters the chamber, it disrupts the current and triggers the alarm.

Ionization alarms are typically more responsive to the flaming fires that occur when wood, paper, or flammable liquids are burning. Because most house fires are categorized as flaming fires–meaning they have more flame than smoke–ionization alarms are quite a bit more popular with homeowners.

However, while ionization alarms are ideal for fires with aggressive, open flames, they are less effective with the smoldering type of fires. For that reason, there is another type of alarm to consider—the photoelectric smoke alarm.

What is a photoelectric smoke detector?

Unlike ionization smoke alarms, photoelectric alarms employ a light source and sensor to detect smoke. As soon as smoke enters a light-sensing chamber, the smoke particles deflect the LED light beam into a photo sensor in a different compartment of the chamber. When the light beam hits the sensor, the alarm sounds immediately.

Because smoldering fires often fill a room with toxic fumes and dangerous smoke well before moving to an open flame, photoelectric detectors are superior at early detection.

The photoelectric vs. ionization smoke alarm debate

Which of these is the best type of smoke detector? How can anyone predict which kind of fire you might encounter?

The U.S. Fire Administration (USFA) weighs in on the ongoing controversy about which type of smoke alarm is most appropriate for protecting people in their homes. Referring to the extensive scientific research completed over many years, the USFA offers the following guidance on smoke alarms:

  • Ionization smoke alarms tend to respond faster to the smoke produced by flaming fires than photoelectric smoke alarms.
  • Photoelectric smoke alarms tend to respond faster to the smoke produced by smoldering fires than ionization smoke alarms.
  • The type of smoke produced by fire depends on the kind of fire. Flaming fires have a different kind of smoke than smoldering fires.
  • Both smoke alarms will detect the smoke from either a smoldering fire or a flaming fire.
  • In some full-scale fire tests, the difference in the time to alarm between ionization and photoelectric smoke alarms was trivial. In other full-scale fire tests, the difference in response time was considerable.

Take the safer route and install both types

According to the USFA, the best way to improve your safety is to install both types of smoke detectors in every room where a smoke alarm may be needed. The fact of the matter is no one can predict which kind of fire you might face. Because smoke detectors have become affordable for nearly anyone, there is less reason for anyone not to have both ionization and photoelectric detectors in your house or apartment.

Location of smoke alarms is critical

The location of a smoke alarm within a home is as essential as the type you choose. Here are suggestions from the National Fire Protection Association (NFPA):

  •  Mount smoke alarms high on walls or ceilings, with wall-mounted not being more than 12 inches away from the ceiling.
  • Install smoke alarms inside each bedroom, outside each sleeping area, and at every home level.
  • On levels without bedrooms, install alarms in the living room or near the stairway to the upper level, or both.
  •  Install alarms at least 10 feet from a cooking appliance to prevent false alarms when cooking.
  • Do not place smoke alarms near windows, doors, or ducts where drafts could interfere with their operation.
  • Install an alarm on pitched ceilings within 3 feet of the peak but not within the peak’s apex.

Smoke alarms are your first line of defense

Even though they realize the importance of smoke alarms, many homeowners neglect them by failing to replace the batteries in them regularly. Decrease your chances of becoming a victim of a house fire by installing and maintaining smoke alarms.

Add the right homeowners insurance coverage to your line of defense. The insurance experts at NSI Insurance Group are here to help you. Use the convenient contact form, call us at 305-556-1488, or send us a message at info@nsigroup.org.

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