Stop 46 – What Is a Fire Sprinkler?

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So how does a sprinkler actually work? Each sprinkler head is its own little heat detector, connected to pipes full of water under pressure.

When a fire heats the sprinkler to its set temperature, usually around a hundred sixty-five degrees, a small metal link melts, or a tiny liquid-filled glass bulb shatters. That opens just that one sprinkler, right over the fire, and sounds an alarm at the same time.

Here's something the movies get wrong: sprinklers don't all go off at once. Only the ones near the fire open. In fact, most fires in buildings with sprinklers are handled by just one or two heads.

There are four main types of systems. Wet pipe systems keep water in the pipes at all times. Dry pipe systems hold air, for buildings that could freeze. Preaction systems wait for a separate detector before filling with water. And deluge systems open every sprinkler at once, for special hazards.

Thank you for visiting the museum, and for honoring the firefighters who have protected Nebraska City for more than a hundred sixty years.