Fires are a significant disaster. People have to fight them relentlessly. In the past, to extinguish flames, pipes with holes were installed under the ceilings of warehouses, sealed with plugs made from low-melting alloys. As soon as the air heated up to a few dozen degrees, the plugs would melt, and water would pour out from the holes. But by the time the air warmed up, the fire had already destroyed many valuables.
More sensitive devices were then introduced—mercury thermometers or thermal relays with bimetallic strips that respond to rising temperatures.
Recently, specialized devices with photoelectric sensors have emerged. Don’t even think about lighting a match in a warehouse equipped with such a device! In an instant, torrents of water will come pouring down on you, and you’ll have to dry off in the fire department’s duty officer’s office.
The device, upon detecting the light from the match, will activate the water and won’t forget to sound the fire alarm.