How a Fire Sprinkler System Works

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An automatic fire sprinkler system is designed to detect, contain and extinguish a fire in its early stages. Sprinklers are also quite useful at keeping a fire in check so it can save property and provide a safe means of access for occupants. But how exactly do they work?

First, it might be helpful to dispel some misconceptions about these life-saving systems that continue to persist.

Here are just a few false narratives:

  • Sprinklers cause more damage in the event of a fire than the fire itself as a result of extensive water damage.
  • Smoke alone triggers a fire sprinkler.
  • A fire sets off the sprinklers
  • Smoke detectors set off fire sprinklers.
  • Once one automatic sprinkler switches on, so do all sprinklers in the system.
  • Fire sprinklers automatically shut off once a fire is under control.

None of the above misconceptions are actually true. Installing a fire sprinkler system doesn’t mean choosing water damage over fire damage or having sprinklers go off in the entire apartment complex every time someone burns a piece of toast. The functioning of sprinkler systems have more nuances than that.

Here's how they really work.

How are Fire Sprinklers Activated?

Automatic fire sprinkler heads have a heat-sensitive element that activates the sprinkler head.  In most cases, this element is a glass bulb filled with a glycerin-based liquid that expands and bursts when the air around it reaches a certain temperature, typically between 135-165 degrees Fahrenheit in wet pipe and dry pipe systems. Other fire sprinkler heads have a soldered link element that melts when exposed to a certain temperature. 

So, sprinklers are not actually activated by smoke they are actually activated by heat.Which is one of the elements of the fire triangle. But it’s easy to see why people think so. After all, heat is carried upward alongside the smoke from a fire.

Once the bulb shatters, the sprinkler head activates, letting pressurized water from the piping system flow out. Note that only the sprinkler head or sprinkler heads nearest the fire will activate, which means the extinguishing action is generally concentrated in the region of the flames.

Types of Fire Sprinkler Systems 

Sprinkler systems include a network of piping filled with pressurized water. The water must be pressurized to allow it to spray outward in an arc, increasing the sprinkler's efficiency at suppressing fire and preventing it from re-igniting.

There’s some variance among the different types of fire sprinkler systems as to how they work and where the water is stored.

Wet pipe sprinkler systems

Wet pipe fire sprinkler heads have a relatively simple design as the water is constantly maintained within the sprinkler piping. For this reason, wet pipe systems have the fastest response time of any fire sprinkler systems. They are also easier to install, modify, and maintain. However, wet pipe sprinkler systems may not be ideal in regions where pipes are likely to freeze or in facilities where a leak could have devastating impacts.

Dry pipe sprinkler systems

In dry pipe systems, the pipes are filled with pressurized air or nitrogen while the water is kept back behind a valve on the base of the system. Once a fire is detected, pressure in the piping drops, the air or nitrogen escapes, and water flows through the piping and out onto the fire. These systems are great for use in areas where frozen pipes are a cause for concern.

As for pre-action sprinkler systems, water is held back using an electronic “pre-action” valve that can only be activated in the presence of both heat and smoke, at which point water flows into the piping.

Talk to a Fire Sprinkler Systems Expert

A fire sprinkler system can activate, contain, and even extinguish a fire in far less time than it takes for the fire department to arrive on the scene. Every building or industrial facility is unique, requiring a personalized fire protection solution. Get in touch with Brothers Fire and Security to discuss sprinkler requirements or monitoring services.