User Manual

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Siemens Switzerland Ltd
Building Technologies Division
this way an incipient stage fire can be suppressed at its source as only those sprinklers in the immediate vicinity of
the fire will be activated, minimizing any unnecessary water damage.
Currently several premiere cultural heritage institutions have installed, or are in the process of installing, complete
automatic sprinkler protection. Examples include the Library of Congress, the Smithsonian Institution, the
National Library and Archives of Canada and the National Library of Scotland.
Wet-pipe automatic sprinklers represent an effective solution for typical museum and library fire-suppression
objectives. To limit the structural intrusion of such a system, partial coverage may be an acceptable compromise
where sprinklers are only installed in particular parts of the building.
Wet-pipe systems As historical buildings and museums are generally not subject to freezing or
overheating (+95 °C) during the year, the most appropriate type of sprinkler is
the wet-pipe system. Such systems are permanently filled with water, which is
maintained under pressure so that in case of fire the water can be immediately
discharged from the sprinklers.
Water mist systems An emerging fire-sprinkler technology which shows great promise particularly for
sensitive applications is the use of water mist. A fine water vapor is generated by
delivering water to the specially designed sprinkler heads at very high pressures.
This maximizes the cooling effect of the water, enabling fires to be extinguished
with minimal amounts of water. Experimental tests have shown that many room
fires can be controlled with as little as 2-3 liters of water. This type of system is
usually activated by control signals from the fire detection system, in response to
the alarm signals from the connected ASD devices.
The disadvantages of this type of system compared with traditional wet-pipe
systems are that they are somewhat more expensive to install and the
maintenance costs are also higher.
5.3.2. Gas extinguishing systems
The main application area for gas extinguishing systems is the protection of closed rooms. They are particularly
suitable for rooms that contain sensitive objects or equipment where water cannot be used. These typically
include all types of electrical equipment and computer rooms.
The gases are stored in pressurized cylinders:
· The non-liquefiable inert gases Ar, N2 and gas mixtures are stored in gas cylinders at a pressure of 300
bar.
· In high-pressure systems CO2 (which does liquefy under pressure) is stored in gas cylinders at 56 bar; in
low-pressure systems it is stored in large cooled containers.
· Clean agents such as HFC227 ea and Novec 1230 are stored in gas cylinders pressurized with nitrogen,
which acts as a propellant. The industry’s most common storage pressures are 25 bar (particularly in the
USA) and 42 bar, which allows for higher flow rates, smaller pipe diameters and longer pipe runs.
Extinguishing is controlled either manually or preferably automatically by means of a fire detection system. Only a
quick, faultless actuation prevents consequential damage, as a fire should be extinguished during its incipient
phase. However, to prevent human casualties, an alarm must first be sounded to warn people of the imminent
flooding of the area. The gas will only be released after a predefined delay has given people sufficient time to
evacuate the area. The extinguishing gas will then be released and a homogenous concentration is quickly built
up throughout the room. To completely extinguish the fire, this concentration must be maintained over a
sufficiently long period of time.
Such systems may be appropriate in modern dedicated museums, which have sensitive enclosed archives,
computer rooms, or similar electrical equipment facilities.