How Do Fire Sprinkler Systems Work?

You’ve probably watched movies where a little fluff of smoke triggered all the fire sprinklers in the building at once. But did you know that even a large volume of smoke isn’t enough to trigger fire sprinklers—let alone activate them all at the same time?

Fire sprinklers are actually triggered by extreme heat, not by the presence of smoke. Also, only one sprinkler head gets activated at a time. In fact, only one or two sprinkler heads are usually required to extinguish fires.

However, are fire sprinklers worth it, especially for your newly-constructed home? The answer is an absolute yes. Fire sprinklers help mitigate the fire and prevent it from spreading all over your home, reducing the likelihood of mortalities by up to 85%.

Aside from that, do they cause severe water damage to your property? Of course, not—fire sprinklers are water efficient. They only need a small amount of water to extinguish the fire and stop it from spreading.

These are just some common misconceptions people often wonder about when they hear the term fire sprinklers. In this article, you’ll discover how they actually work, and all of the myths about them will be busted out. Continue reading below to learn more.

What Are The Basic Parts Of A Fire Sprinkler System?

In order to understand how the system functions, it’s a good idea to know the different parts and mechanisms that make up the system. These include:

• Automatic Sprinkler Heads: These are the parts of a fire sprinkler system you often see in a building that releases water to extinguish the fire. There are different types of automatic sprinklers that suit varying settings and needs. These include upright, pendant, concealed pendant, and sidewall sprinkler heads.
• Heat Sensitive Element: This is a crucial component of every fire sprinkler. It’s the trigger responsible for the activation of the sprinklers. The most common one is a small glass bulb with a glycerin-based chemical inside. This bulb will expand in response to increasing temperature until it bursts at around 135F to 165F.
• Sprinkler Cross And Main Pipes: These are the pipes that run across the ceiling and walls, carrying and storing pressurized water to be released through the automatic sprinkler head when a fire strikes.
• Sprinkler System Risers: These pipes connect the cross and main pipes to the main water source of the building.
• Fire Sprinkler Pressure Gauges: These are gauges responsible for measuring the water pressure inside the fire sprinkler system. They’ll tell you if there’s enough pressure to be used to disperse water effectively when a fire strikes.
• System Control Valves: These valves are responsible for draining, testing, and isolating different parts of the sprinkler system.
• Water Flow Switches: These switches will be activated when water starts to run through the pipes. Then, they’ll send a signal of fire disaster to authorities to ask for help.
• Water Motor Gong: This is the component that produces a sound alarm when there’s active water running through the system.
• Main Drains: These are where the water in the system exits during maintenance and testing.

Now that you know the basic parts and mechanisms of a fire sprinkler system, it’ll be easier to understand how the entire process works.

How Are Fire Sprinklers Triggered?

A fire sprinkler system has a heat-sensitive trigger mechanism that activates when a fire breaks out. This can be either a small glass bulb or a fusible metal link that contains a heat-sensitive liquid that expands and bursts as the temperature rises.

Here’s a detailed discussion to help you better understand each trigger mechanism:

• Small Glass Bulbs Filled With Glycerin-Based Liquid

When a fire sparks, the air starts to heat rapidly. This heated air rises toward the ceiling and other areas where fire sprinklers are installed. When the air reaches a specific temperature—usually 135F (57C), 155F (68C), or 250F (121C), the heat-sensitive liquid inside the small glass bulb expands until the glass breaks due to pressure.

If you use a wet system, the pressurized water in the cross and main pipes will be released through a deflector plate consistently in a single pattern across the room. The water will flow continuously until the main source is shut or runs out of supply.

On the other hand, if you use a dry system, the triggered sprinkler forces the air pressure stored in the pipes to fall. This opens the pipe valve that prevents the water from gushing out. Then, the water will be released through the activated sprinklers—this process may last up to 60 seconds.

• Fusible Metal Links

Fusible metal links are the exact opposite of glass bulbs. Instead of small bulbs with glycerin-based liquid, these trigger mechanisms use two metal rods fused using a solder with a pre-established melting point.

When the air reaches a specific temperature (pre-established melting point), the solder will begin to melt, causing the two metal rods to pull apart. Then, the pressurized gas and stored water will be released through the sprinkler head.

How Are Fire Sprinklers Turned Off?

Many people believe that fire sprinklers automatically shut down after the fire has been thoroughly extinguished. But that’s not the case.

When a fire is extinguished, the system has to be manually turned off to stop the continuous release of water. However, if the shutdown is due to malfunction, the sprinkler system may need to be repaired or replaced before reset.

This is why it’s a good idea to know where the system risers are. With this, you’ll be able to control the water flow by turning the valve on and off. Don’t worry if you don’t know where they’re installed. During the actual fire, the authorities will most likely take care of this step.

However, knowing where these risers are can still be helpful, especially when it comes to system malfunction and pipe damage. This will help you stop the water flow and prevent unwanted water damage.

Final Words

Fires have the potential to destroy properties or, worse, take lives. While having fire insurance for such situations is beneficial, you should take extra precautions by installing fire sprinklers in your home. Fire sprinklers are one of the best ways to protect your home from destructive fires. These will help prevent fire from spreading quickly throughout your home. Now that you know how fire sprinkler systems work, this may be the right time to call the local fire safety services and protect your home right away.