The earliest methods of fire alarm use were shouting, banging gongs, and ringing bells. Early American night watchmen used wooden sirens, which later evolved into hand-cranked alarms. After the invention of the telegraph in 1837, American physician William Channing developed a manual fire alarm system (alarm box) using radio technology and Morse code. This system became widespread in Boston in 1852, and the telephone eventually replaced the telegraph.
In the early 20th century, constant-temperature fire detectors were invented, followed by differential-temperature fire detectors in the 1920s. In 1902, British engineer George Darby invented the "Butter Sentinel," the precursor to the modern smoke alarm. In 1941, Switzerland invented the ionization smoke detector. Smoke alarms entered the market in 1951, and in the late 20th century, photoelectric smoke detectors were invented and widely used.
By the late 1990s, most residential and public buildings in developed countries had installed automatic fire alarm systems or stand-alone fire alarms, and their application in my country is also becoming increasingly widespread. With the rapid development of technology, fire alarm systems are rapidly evolving towards intelligent and interconnected systems that utilize microprocessors, forming a "three-sensor" intelligent fire protection platform system that integrates smoke, temperature, and combustible gas detection.
