User Manual

Siemens Switzerland Ltd

Building Technologies Division

always require a site-specific design, as all pipe diameters and nozzles must be

calculated individually according to the particular application.

Modular systems, on the other hand, consist of space-saving compact units that

are installed within the protection zone itself. These units combine fast and

reliable detection with quiet and safe extinguishing in one compact package.

They are particularly suitable for the protection of small enclosures with volumes

up to 120 m

that contain electronic and electrical equipment. The main cost-

saving advantage of such systems is that they can be installed quickly and easily,

and service and maintenance costs are very low.

Figure 4.4.2-1 Modular and centralized extinguishing system

Kitchens The fire risk in kitchens is relatively high. This is due to a combination of the

cooking materials used (cooking oils, fats, etc.) and the hot cooking equipment

(hot-plates, ovens, vats, etc.). Kitchen fires are predominantly fat fires, which

often start spontaneously and rapidly generate an intense heat. The flames are

also fed by the highly combustible fat vapors and can only be checked by

interrupting the oxygen supply and reducing the temperature of the cooking oil.

An additional problem related to kitchen fires is their inherent ability to spread

through the kitchen’s own air extraction system to the rest of the building. The

critical areas (e.g. cooking range, deep fat fryers, ovens and air extraction

system) should be protected by specially designed extinguishing systems. Wet

chemical fire extinguishers (Class F) should also be provided.

When extinguishing systems are used in commercial kitchens, then these are wet

chemical systems, which are installed immediately above the protection area or

within the air extraction hoods. They are stand-alone systems, which both detect

the fire and extinguish it automatically. The effectiveness of this extinguishing

agent relies on the cooling of the hot surfaces together with a highly efficient fire

suppression mechanism. On contact with the hot fat, the extinguishing agent

foams up to produce a soapy layer. This creates a dense barrier between the hot

fat and the surrounding air, effectively preventing the highly volatile fat vapors

from escaping and reigniting the fire.

If the hotel is equipped with a sprinkler system, then this should be extended to

protect the other parts of the kitchen. However, it must be ensured that the

water spray from the sprinklers cannot reach the critical areas of the cooking

range, deep fat fryers, ovens and air extraction system.