How Sprinkler Heads Work
Each sprinkler head contains a heat-sensitive element, usually a glass bulb filled with liquid or a metal piece that holds a cap in place. When fire heats the air around the sprinkler head to a certain temperature, this element breaks or melts. Once it breaks, water pressure forces the cap open and water sprays out in a specific pattern, typically in a circular or semi-circular spray.
Water Supply System
Fire sprinkler systems are connected to the building's main water supply through underground pipes or connected to elevated water tanks. The system is always pressurized and ready to go. When a sprinkler head opens, water flows through the pipes and out the nozzle without needing any electrical activation or manual switch. This is why sprinklers work even during power outages.
Types of Sprinkler Systems
Wet pipe systems keep water in the pipes at all times and are most common in heated buildings. Dry pipe systems are used in cold areas and keep pressurized air in the pipes instead of water, which enters only when heat melts a valve. Pre-action systems use both air and water and require heat detection before water enters, giving additional protection against accidental discharge.
Fire Suppression Effectiveness
Sprinklers suppress fires by cooling the flames with water spray and reducing oxygen around the fire. Studies show that sprinkler systems can control or extinguish fires before firefighters arrive in about 9 out of 10 cases. They significantly reduce fire damage, injuries, and deaths compared to buildings without sprinkler protection.
Maintenance and Testing
Fire sprinkler systems require regular inspection and maintenance to ensure they work properly. Building owners must have systems inspected annually, test water pressure monthly, and replace any damaged sprinkler heads. Backup power supplies and water tanks are often tested to guarantee the system functions during emergencies. 
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