User Manual

Siemens Switzerland Ltd 23
Building Technologies Division
4. Extinguishing
4.1. Introduction
When it comes to data centers, NFPA (National Fire Protection Association) provides most details on how to
protect it against fire. NFPA 75 for example says that if a building has a water sprinkler standard, then usually so
should the data center, too. But it needs to be kept in mind that water-based fire protection systems, such as
sprinklers, provide primarily structural protection and not asset protection. Therefore, sometimes complying with
regulations doesn’t necessarily mean that valuable assets are made safe. Also, NFPA focuses on the protection of
the building ‒ and not individual rooms - and recommends sprinklers. However, sprinklers damage the electronic
equipment ‒ for example in a server room ‒ of a data center. For the protection of the delicate electronic
equipment Siemens therefore recommends the use of dry extinguishing systems (i.e. with inert gases or chemical
agents/clean agents). Depending on the application, resp. the rooms to be protected (i.e. server rooms,
emergency power supply, control room, etc.) ‒ as well as the national and regional directives of a country ‒
different solutions are appropriate.
4.2. Principles
For a fire to exist, three elements need to be present:
• Heat to raise the material to its ignition temperature
• Oxygen to sustain combustion
• Fuel to support the combustion
Extinguishing a fire implies interfering with the combustion process in such a way that the preconditions to
maintain combustion are no longer present. This can be achieved by removing any one of these three elements or
by interfering directly with the combustion process. This results in the four basic extinguishing mechanisms:
• Reducing the temperature of the inflammable materials or the flames (cooling)
• Cutting off the supply of oxygen (smothering, inerting)
• Physically separating the inflammable materials from the flames (starvation)
• Use of chemicals to inhibit the combustion process