The Differences Between Ionization and Photoelectric Smoke Alarms
Ionization or photoelectric–which smoke detector is best for you? Before you can decide, you need to know the difference between the two.
Ionization and photoelectric devices are the two most commonly recognized smoke-detection technologies. Each has a sensor that detects smoke and fire differently depending on the origin of the fire.
Ionization smoke detection is typically more responsive to flaming fires. For example, a towel is placed on a kitchen counter too close to a stove burner and it ignites.
Photoelectric smoke detection is generally more effective at sounding when a smoldering source is detected. When a lit cigarette falls between sofa cushions, for example.
Most homes today have ionization-based smoke alarms, mainly because they are less expensive. The ions, or electrically charged particles, in these alarms are what detect smoke in the air.
The biggest complaint about ionization-based smoke alarms is they give off too may “false alarms” (such as from cooking or steam from showers). So homeowners often disconnect them or remove the batteries. Not a wise option. Better to install them a little farther away from kitchens and bathrooms.
The photoelectric smoke detector uses a light beam to detect the presence of smoke. This type of smoke-detection technology can be minutes faster than an ionization unit in responding to a smoldering fire. With cost a major factor in the typical homeowner’s decision, it’s worth noting that the photoelectric device typically costs twice as much as the ionization type.
The National Fire Protection Association says having both alarm technologies in your home is the best protection. You can purchase a dual-sensor device, which is made up of both ionization and photoelectric technology. Or, if you already have an ionization-type unit in place, install a photoelectric smoke detector next to it.
How do you know if you have an ionization smoke detector? Look on the back of the device. The ionization-type alarm contains a trace of radioactive material called Americium 241, so a warning will be posted on the outside of the unit.
No matter what kind is chosen, every home should have some type of smoke-detection technology and a sufficient number of devices properly installed and in working order.