The fire sprinkler industry takes many precautions to ensure that accidental leakage does not occur. However, if an automatic sprinkler has discharged water in the clear absence of a fire, an investigation should be undertaken to determine why the sprinkler operated. In most cases, a reason can be found.

When temperatures drop in the Southeast, sprinkler systems can sometimes malfunction as a result of these conditions. Sprinkler freeze failures seem to be less common in northern states because building owners and sprinkler system installers are more cautious since freezing weather is expected.

A Sprinkler Freeze Failure Scenario

If a portion of a sprinkler system is exposed to freezing temperatures, water in the piping can turn to ice, expand in volume, and produce thousands of pounds of pressure. The pressure can break fittings and force sprinklers to operate. As a result, water leaks or is discharged from the system when the ice blockage thaws. Sprinkler system failures due to freezing normally aren’t discovered until after the water begins discharging and starts to cause damage.

After a sprinkler system water discharge, building owners face property damage, business interruption, and irate tenants and customers. Most fire sprinkler contractors have the ability to eliminate the chances of a freeze failure with proper installation, but to make sure it never happens, building owners also need to be involved.

Wet System Freeze Failures

According to NFSA, most sprinkler systems are wet pipe systems, meaning that the piping is normally filled with water. A wet system freeze failure has two primary causes:

  • The system lacked adequate heating
  • The system lacked adequate insulation

Installation standards define how and where wet piping systems are supposed to be installed, but part of the responsibility rests with building owners and operators. According to paragraph of NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems:

“The building owner shall ensure that all areas of the building containing water-filled piping shall be maintained at a minimum temperature of 40°F (4.4°C) and not exposed to freezing conditions.”

A wet system freeze failure can occur in an area where a building used to be heated, but is now left cold or where a piece of insulation is disrupted, leaving piping exposed. In either scenario, the building owner has the ability to prevent the freeze failure with regular maintenance and inspection.

Dry System Freeze Failures

Despite the name, dry sprinkler systems can also have failures due to freezing in cold conditions. A dry pipe sprinkler system is a specialized type of fire sprinkler system that is typically installed in areas of a building that are subject to freezing. As its name implies, the pipes are normally dry and charged with compressed air. The compressed air holds the dry valve closed and prevents water from entering the system. When a sprinkler activates, the compressed air leaks out, the valve opens, and the system piping is filled with water. If the dry system is properly installed, the water will drain, but that doesn’t always happen.

In addition, if a dry system’s pipes are not sloped back towards the source or an auxiliary drain, the water will pool within the piping. When winter comes around, the uninsulated piping freezes, creating problems just like a wet system freeze failure. In buildings where there is a low quality of construction, this is a common scenario. Residential buildings where construction is fast and lacks proper oversight are particularly prone to dry system freeze failures.

Most fire sprinkler freeze failure scenarios are entirely preventable. For tips, continue reading our post, How To Prevent Sprinkler System Freeze Failures.

By Jeff Harrington, CEO and Founder of Harrington Group, Inc.