Reference
Residential Sprinklers - Are they all wet?
By Mark C. Hughes, P.Eng.
© 2005 Sintra Engineering Inc.
I recently came across some interesting results regarding residential sprinkler systems. These are something that has been around for a long time, but has limited use in real housing. Residential sprinklers are used in residential installations including single family and smaller multi-family installations. They have been around for almost 30 yearsÖ.so why are they not more extensively used? While recognized that theses fast-response sprinklers protect life and property from fires, less than 3% of the one and two family homes in the United States have them installed.
In addition to their fast-response characteristics, residential sprinklers have a different water distribution pattern from conventional sprinklers. Effective control of residential fires is often dependent upon a single sprinkler in the room of fire origin, so the water distribution pattern of residential sprinklers must be more uniform than standard sprinklers, which can rely upon the overlapping patterns from several sprinklers. Residential sprinklers are also required to wet couches, drapes and similar furnishings at the edge of rooms. In their discharge patterns, the sprinklers must be capable of delivering water to the walls in the areas where they are installed and high enough up on the walls to prevent the fire from getting above the sprinklers. The water delivered close to the ceiling not only protects the portion of the wall close to the ceiling, but also enhances the capacity of the spray to cool gases at the ceiling level, thus reducing the likelihood of excessive sprinkler openings. These design features significantly improve their effectiveness in single family dwellings.
In Arizona, a number of communities have required residential sprinkler systems in all new construction single family dwellings. In particular, Scottsdale Arizona conducted a 10 year study after the start of the initiative (1986) to evaluate the benefits. The installation costs for these sprinkler systems dropped by about 45% from 1986 to 1996. In addition, home insurance companies provided an average discount of 10% per year for homes with residential sprinkler systems.
The Scottsdale study also examined water usage during fire incidents. By 1996, in more than 90% of the incidents, the fire was controlled with only 1 or 2 sprinklers activated. The average amount of water flowed by the sprinklers was 299 gallons per fire which could be compared to an estimated manual suppression usage of approximately 6,000 gallons per fire. More importantly, the study indicated that at least eight lives were saved in these fires by the use of residential sprinkler systems.
In these days where new construction materials (such as engineered truss joists) are permitted in new home construction but can lead to fires that develop very quickly and result in much more significant damage, no similar implementation for safeguarding new home construction has occurred. This is particularly significant when municipal infrastructure and fire departments are under continued stress to deliver more with fewer resources in more distant suburban developments.
Mark Hughes, P. Eng. is a principal with Sintra Engineering, a Forensic Engineering firm.
return to Reference articles...
