Smoke detectors are devices that automatically sound a warning when they sense smoke or other products of combustion. They are usually mounted on a wall or the ceiling. When people are warned early enough about a fire, they can escape before it spreads. You can purchase one starting at $6. Every year house fires kill thousands. Fire kills an estimated 4,000 Americans every year. Another 30,000 people are seriously injured by fire each year. Property damage from fire costs u