Vanguard Smokesonic: in the Line of Fire

In the first half of the 20th century, most automatic fire alarms were heat-activated. Starting in the 1950s, however, more sensitive smoke detectors were introduced, working on one of two detection principles: photoelectric and ionization. In this video, we look at three different smoke detectors and discuss how this life-saving technology evolved over time. Wilkinson Alarm Video:    • SHORT: Wilkinson Fire Alarm   Merlite Alarm Video:    • SHORT: Merlite Fire Alarm   Guardsman and Vanguard Alarm Video:    • Guardsman and Vanguard Alarms: A Technolog...   SOURCES https://www.scribd.com/document/14390... https://carlwillis.wordpress.com/2017... https://www.diyphysics.com/2013/01/20... https://www.mysmokealarm.org/smoke-al... https://patents.google.com/patent/US3... https://patents.google.com/patent/USD... https://patents.google.com/patent/CA1... https://forums.thefirepanel.com/t/som...