When two metals with different coefficients of thermal expansion are bonded together and then heated, differential expansion causes bending toward the metal having the lower expansion rate. Very complex operation but compensates for thermal lag. Can be added where insufficient tubing exists for proper signal size. Locations close to sleeping area are essential. Smoke Detectors - Provides faster response to smoke generated by an open flame fire.
Smoke reduces the ability of radioactive ions to form a conductor and the alarm is activated.
Low battery voltage also indicated. B. Photoelectric Smoke Detectors - Provides faster response to smoke generated by a smoldering fire. Smoke interferes with a light beam reduces the light intensity of the receptor and the alarm is activated. Light Obscuration Principle - Good for large areas. The density of a cloud in the chamber is measured.