As early as 1890, inventors were working toward making a detecting system for fires in homes and businesses. While initial fire alarm systems were based on detecting temperature differences, systems in the 1930s introduced the detection of smoke. By the late 1960s, smoke alarms were present in many commercial properties. By the mid-1970s, they were growing in popularity in homes across America. (see Reference 1)
There are two main types of smoke detectors: ionization and photoelectric. In ionization detectors, a small amount of radioactive matter is placed between two plates charged with electricity. The air is ionized as it flows between the plates. Smoke, however, disrupts the flow of the ions and causes the plates to meet. This creates an alarm. (see Reference 2)
Since ionization detectors are based on the interruption of ions, the introduction of foreign particles into the detector can create problems. If left dusty and untended, these alarms can trigger at any time regardless of the presence of fire or smoke. In addition, insects can get trapped in the sensor. Clean the alarm with a vacuum or compressed air to remove dust and other debris. (see Reference 3)
Photoelectric detection is based on smoldering fires. In these detectors, a light is aimed at the sensing chamber but away from the sensor. When the smoke caused by the smoldering enters the chamber, it disrupts the flow of light and causes it to reflect onto the sensor. This sets off the alarm. (see Reference 2)
Since these alarm systems are based on the presence of smoke, burned food, cigarettes or extinguished candles can also trigger them. In addition, high humidity or pollen can sometimes cause unwanted reactions. To help prevent these nuisance alarms, place the smoke detector away from the kitchen, and clean the detector regularly. (see Reference 3)
If other problems are occurring with your smoke detector, change the battery. In addition, test the smoke detector occasionally to ensure that it still works. If the detector is not working properly and continues to have problems after troubleshooting, purchase a new detector.