User Manual

Siemens Switzerland Ltd 32
Building Technologies Division
Protection of room In a data center configuration with cold / hot aisles (see fig. 4.4.2-2 and 4.4.2-3),
the extinguishing flooding process presents some differences compared to
traditional room flooding.
• The flooding of the racks with circulation system active (considered to
be the expected situation) will mostly occur through the nozzles located
in the false floor.
• For the calculation of extinguishing volumes, it is recommended to
consider the false floor (zone 1) and the ambient (zone 2) as showed in
the fig. 4.4.2-2 and 4.4.2-3, respectively for cold / hot aisle systems with
and without housing.
• Since the cooling system will not be stopped, it is important to take into
account in the total volume calculated for the extinguishing agent, the
additional volume of the circulation system (if system located inside the
room this should be disregarded).
• Before the flooding process is initiated, the fresh air inlet should in all
cases be shut off (closed system).
Figure 4.4.2-2 Fire extinguishing in cold / hot aisle without containment
Figure 4.4.2-3 Fire extinguishing in cold / hot aisle with containment
Protection of ceiling void
and raised floors
Modern trend is that cables are routed along the ceiling over the racks, with
power cable rails and data cable trays on the ceiling, without dividing the room
to form the so called ceiling void. Different for raised floors, there the trend is to
keep the room divided, mainly for circulating the cooled air back into the room
through cold aisles or racks. Nevertheless, it is still usual to find data centers that
both have raised floors and ceiling voids. A proper engineering concept should
always consider the entire volume, including raised floors and ceiling voids, to
assure the extinguishing agent concentration and consequently efficiency of the
extinguishing system.