When most people think of fire sprinkler systems, they picture a movie scene: the hero needs a distraction, pulls the alarm, and boom, every sprinkler in the building erupts at once.

Cool visual. Total myth.

Let’s clear up the Hollywood version versus how they actually work.

Automatic fire sprinklers have been around for nearly 150 years, and while the technology has advanced, one thing has never changed: they don’t all go off together. Each system is designed for a specific purpose, and only the right head activates when it’s needed.

Here are the four types you’ll most often find in commercial spaces:

Wet Pipe Systems
The classic setup. Pipes are filled with water and ready to respond. When a sprinkler head gets hot enough, it opens and sprays water over a designated area, and only that area. These systems are ideal for temperature-controlled environments or warmer climates where frozen pipes aren’t an issue.

Dry Pipe Systems
For spaces where freezing is a concern. Instead of water, the pipes are filled with compressed air. When a sprinkler head activates, the air releases first, allowing water to flow in. You’ll see these in unheated areas like loading docks, parking garages, and warehouses.

Pre-Action Systems
Think of this as a double-check system. Like dry pipe, the pipes stay empty until needed. Water will not flow until two things happen: a detection system triggers and a sprinkler head activates. That two-step process helps prevent accidental discharges, making it a reliable choice for data centers, museums, and archives.

Deluge Systems
Here’s the one that is a little Hollywood. Deluge systems use open sprinkler heads. Once the fire detection system sends the signal, water floods from every head at once. They’re designed for high-hazard areas like aircraft hangars, power plants, and chemical storage facilities.

Every building has unique risks, and the right sprinkler system makes all the difference.