There are two main technologies used for smoke alarms: photoelectric smoke detector and ionization smoke detector. A smoke alarm can use one or both of these technologies to create a fire warning. These devices are usually attached to 120-volt house wiring, but they can also be powered by a lithium or 9-volt battery.

Photoelectric

A photoelectric smoke detector uses a light sensor and light-emitting diode inside a sensory chamber. If smoke flows into the chamber, it scatters the light beam and sets off the alarm. If the area is normal, the light beam should beam horizontally. A photocell placed at the bottom of the device will trigger the alarm if enough light is refracted vertically.

Ionization

An ionization smoke detector uses a small quantity of radioactive material for ionizing the sensor chamber. This allows the air chamber to conduct electricity, generating a current flow between two electrodes. If smoke enters the chamber, it causes the conductivity to decrease. If the conductivity decreases past a certain level, an alarm will go off.

Which is the Best?

The type of alarm you choose should depend on the room. Ionization devices are best used in rooms that have highly-combustible liquids that may create large-flame fires. These materials include paint, cleaning solutions, newspapers, and other flammable liquids.

Photoelectric devices are best suited for kitchens, bedrooms, and living rooms. There rooms have large pieces of furniture that burn slowly, creating smoldering fires instead of large flames. It is impossible to determine which sensor is universally better for catching all kinds of fires. Each sensor is designed to respond to flaming fires or smoldering fires, so it will largely depend on the material being burnt.

Common Nuisances

27% of detector nuisances come from faulty power connections. Professional electrician services should be used to ensure the device is properly installed into the electrical system. Another 28% of nuisances come from kitchen detection, so avoid placing the detector nearby the stove or another area that regularly produces large amounts of smoke or heat.