Residential and commercial fire sprinkler systems present differences in design and capabilities that are important to consider in risk assessment. Awareness of these differences in system design and water supply requirements make considerable differences in evaluating values at risk and risk assessment of pure property protection versus the safety of occupants. To consider commercial and residential fire sprinkler systems identical in a risk assessment invites gaps in the assessment. This paper is not intended to cover both commercial and residential sprinkler system design in detail - beyond a brief recap of the purpose and functions of fire sprinklers. Certain knowledge of commercial automatic fire sprinkler systems is assumed.
Any fire alarm system provides three critical functions:
Detect - sense a fire event
Alarm - provide a warning to occupants that the system has activated so they may take action
Communicate - provide a notification away from the occupants that the system has activated.
These three functions are the same for any fire protection system. Smoke detectors have the same basic function as automatic fire sprinklers. The difference is the application of control measures by fire sprinklers in addition to the alarm.
As safety professionals, being prepared to dispel unfounded rumors and misunderstandings are important when discussing automatic fire sprinklers. This list has the most common arguments against fire sprinklers and points that can be used to overcome each.
They are unsightly
Sprinklers go off accidentally and leak
They all go off at the same time
They cause water damage
They are too expensive
They don't save lives
Current sprinkler design uses painted and coated sprinkler heads that blend in easily to almost any environment. Sprinklers can be recessed and covered with plates that hide the entire unit - important for residential applications.
The actual experiences of accidental sprinkler discharges are remote. Factory Mutual reported that the probability of an accidental sprinkler discharge due to a manufacturing defect is 1 in 16 million sprinklers per year in service. Where sprinklers do discharge accidentally, it is most often caused by direct physical damage - using a sprinkler as a coat hanger for example. Actual occurrences of leaks are remote. But, even if a sprinkler does accidentally go off, will insurance respond? Most policies are structured to include a sprinkler discharge under the same definitions as any other plumbing leak.
Sprinkler heads are individually activated unless of a specialized design, such as deluge or exposure protection heads. A thermal element within each sprinkler head must "fuse", or melt. This allows the existing water pressure in the pipes to push off the cap and flow water from that specific sprinkler head.
The best argument against this is through calculation. A typical sprinkler head for a light hazard occupancy, like an office, is designed to discharge 0.10 gallons per minute.
