How Fire Sprinklers Work

When fire sprinkler systems are installed in homes, the first thing that's done is to construct a network of pipes throughout the house's ceilings and walls. In most residential fire sprinkler systems, these pipes are filled with water at all times.

In some commercial buildings, these pipes may be filled with compressed air and connected to a water main or storage tank with a valve. This is done to protect the pipes from bursting during sub-freezing weather in buildings that are not constantly heated.

Once the water pipes are in place, the sprinkler heads are connected to the water pipes in your ceiling and walls. The network of water pipes is either filled with water at all times, or hooked up to your water main or a storage tank via a water pump or valve.

Each sprinkler head is designed to go off individually.

Here's how it works:

  • Each sprinkler head contains either a glass bulb filled with heat-sensitive gases and liquids, or a series of seals that melt under extreme heat.
  • The moment a fire starts, a plume of hot gases rises toward the ceiling. This plume is hot enough to expand the gases and liquids in the glass bulb, or melt the fusible links within the sprinkler head-depending on design.
  • Once that happens, a valve connected to the network of pipes releases in the sprinkler head, causing it to eject a flow of water onto the fire. This lowers the fire's core temperature, extinguishing it before it gets out of hand.
  • Fire sprinkler systems are designed so that sprinkler heads go off individually, concentrating the water only in the areas where it's needed. Water damage is typically minimal in homes with fire sprinkler systems installed, as is fire damage.
  • If the fire's core temperature drops below a sustainable amount, it will go out. This is how water usually puts out fire - it lowers the fire's internal temperature so that it cannot maintain its heat.
  • Fire sprinkler systems dump enough water on a fire at its source, which lowers the fire's core temperature before the fire gets a chance to spread out of control.
  • Fire sprinkler systems also protect against death by smoke inhalation. Those caught in a fire often die of smoke inhalation before the fire itself gets to them. Fire sprinkler systems eject water on the smoke produced by a fire, weighing down the larger particles in the smoke and making it thinner and less able to rise. This has saved thousands of lives from death by smoke inhalation enabling people to escape the fire.