The design may differ according to the reference used. APSAD R1 (France), NFPA 13 (USA) and the FM Global standards (USA) are some of the more common references. The reference applied helps determine the various classes of risk corresponding to the building(s) protected by the system. In turn, the overall number of sprinkler heads to be installed can be estimated according to the surface area of the buildings. It is also necessary to ensure that the roof structures can withstand the extra loads of the future sprinkler systems. The cost of reinforcing the framework can be a significant factor.
The class of risk with the greatest constraints is then taken as a benchmark to determine the “worst-case scenario”. The characteristics of the water supply (pump system and tank) can then be defined from this worst-case scenario. In most cases, the pump system must be capable of supplying several hundred cubic metres per hour over a period defined in the reference used. The costs of the sprinkler system equipment can be estimated at this stage. Ancillary work packages, such as civil works and external works, can however have significant financial consequences if the project is incorrectly evaluated at the outset.
The concrete base pad on which the water tank will stand may require special foundations depending on the nature of the soil (geotechnical study). It is also essential to identify the possible presence of ground water and contaminated earth that could generate substantial additional costs. Fire water drainage is also to be taken into account at the start of the project. The building constraints of the pump room, depending on its positioning, are also to be considered and the servicing and maintenance of a sprinkler system must not be underestimated either. Maintenance and servicing contracts are generally costed as an option in the quotes supplied by installation contractors.
It should be noted that the client can negotiate a reduction in their insurance premium with their insurer, helping to offset the cost of the sprinkler system, if the site is subsequently considered a “well protected risk”.