3 min read
An automatic fire sprinkler system is designed to detect, contain, and extinguish a fire in its early stages. Sprinklers are also useful at keeping a fire in check, so it can save property and protect occupants. But how do they work?
First, it might be helpful to dispel some misconceptions about these life-saving systems:
- Sprinklers don’t cause more damage than the fire itself.
- Smoke alone doesn’t trigger a fire sprinkler.
- Smoke detectors don’t set off fire sprinklers.
- One automatic sprinkler trigger doesn’t immediately affect other sprinklers in the system.
- Fire sprinklers don’t automatically shut off once a fire is under control.
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.
Sprinkler system functions have more nuance than that.
Here's how they really work.
How Are Fire Sprinklers Activated?
Automatic fire sprinkler heads have a small heat-sensitive part that activates the sprinkler. Most sprinklers use a glass bulb filled with a glycerin-based liquid that expands as the surrounding air heats up, typically somewhere between 135 and 165 degrees Fahrenheit, until the bulb breaks and triggers the sprinkler. Other fire sprinklers have a small metal piece that melts when it gets hot enough.
Once the bulb shatters, the sprinkler head activates and releases pressurized water from the piping system. Note that only the sprinkler head or heads closest to the fire will activate, so the water stays concentrated in the area of the flames rather than spreading throughout the building.
Types of Fire Sprinkler Systems
Sprinkler systems are built from a network of pipes filled with pressurized water. That pressure allows the water to spray outward in an arc when a sprinkler goes off, helping put out the fire and keep it from starting back up.
There are a few different types of fire sprinkler systems, and they vary in how they work and where the water is stored.
Wet Pipe Sprinkler Systems
Wet pipe systems are the simplest design: water sits in the pipes at all times, ready to go. That’s what makes them the fastest-responding fire sprinkler system, and it also makes them easier to install, modify, and maintain. The tradeoff is that they’re not a great fit for places or areas where pipes are likely to freeze or in facilities where a leak would cause serious damage.
Dry Pipe Sprinkler Systems
In a dry pipe system, the pipes are filled with pressurized air or nitrogen, and the actual water is held back behind a valve at the base of the system. Once a fire is detected, the air or nitrogen escapes, which drops the pressure in the pipes and lets water flow through and out onto the fire. Because there's no standing water in the pipes, these systems are a good choice for areas where freezing is a concern.
The tradeoff is response time. Since the air has to clear out before water can flow, dry pipe systems react a bit slower than wet pipe systems, and they tend to cost more to install and maintain due to extra equipment like an air compressor.
Pre-action systems add an extra safety step. Water is held back by an electronic valve that only opens when it detects both heat and smoke. Once both are present, water is allowed into the piping.
Foam Water Sprinkler Systems
Foam water sprinkler systems combine a regular sprinkler system with a foam mix that blends with the water as it sprays out. That mix creates a layer of foam over the fire that smothers it and helps keep it from flaring back up. These systems are good at handling flammable liquid fires, which is why you'll often find them in places like fuel storage areas, aircraft hangars, and certain manufacturing facilities.
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.
