Fire Sprinkler System Freeze Failures

Freeze failures:

As temperatures drop during the winter months, the possibility exists that your fire sprinkler system could experience a freeze-induced failure. Water expands when it freezes, and under the right conditions, this expansion can cause a rupture of a sprinkler pipe fitting or the activation of a sprinkler head. The resulting water damage can costs tens of thousands of dollars.

Under what circumstances should you suspect a freeze failure?

A freeze failure can occur whenever the temperature drops below 32⁰F, but there is typically a specific weather pattern that takes place prior to the discovery of the failure. First, there is a period of cold weather, during which the sprinkler system experiences the coldest temperatures of the winter season to date. Under most circumstances, the weather outside must be substantially colder than 32⁰F to overcome any building heat leaking into the attic from heated floors below. The sprinkler and/or pipe ruptures take place during the cold weather, but the effects are not realized because the water within the piping is frozen. The water damage is usually discovered on the first warm day after the cold stretch of weather.  Ruptures most often manifest as broken tee fittings or elbow fittings, though sometimes they appear to be activated sprinkler heads.

Failures with wet-pipe sprinkler systems:

Wet-pipe sprinkler systems are filled with water at all times.  They are intended to be utilized only in heated portions of a building.  Wet-pipe sprinkler system failures usually take place during the first cold winter after a major construction or renovation where a sprinkler pipe is installed in an unheated area or is not insulated properly.  Typically, the failure can be attributed to an installation deficiency, rather than a maintenance deficiency.  In some cases, the failures are caused by inadequately maintaining heat within the building.

Failures with dry-pipe sprinkler systems:

Dry sprinkler systems are designed to be utilized in sub-freezing environments.  The sprinkler pipe is filled with compressed air, rather than water.  During normal sprinkler system activation, a sprinkler head opens due to the heat of a fire and air exits through the activated sprinkler, reducing air pressure within the system.  When the air pressure drops to a certain point, a valve opens, admitting water into the system which eventually flows out of the activated sprinkler head.

Dry sprinkler system freeze failures occur when the dry sprinkler system is either partially or completely full of water, rather than compressed air.  The presence of water within the system can be an installation failure where a section of pipe is improperly sloped so that it cannot be drained.  Water in the system can also be a maintenance failure because draining procedures were not implemented properly by the owner or maintenance contractor during the most recent inspection.