User Manual

Fire Safety
44
Building Technologies 049_Archives_and_Libraries_A6
V10271399_a_en.doc
Fire Safety & Security Products 03.2009
 Print or written paper
 Photochemical on paper or board
 Print or written on organic non-paper media (parchment, papyrus, palm
leaves, etc.)
The item listed below are the so called new media, usually producing smoldering
fires, the use of chemical agents is the fastest available alternative. Nevertheless,
solutions based on inert gases and water combined are also applicable here.
 Photochemical on plastic (negatives, X-rays, slides, films, microfilms, etc.)
 Electronic media (magnetic bands, DVD, hard disks, solid state and flash
memories, etc.)
 Print or written on inorganic non-paper media (glass, plastic, etc.)
4.4.2.1 Inert gases and water combined
The extinguishing effect of inert gases (also called natural gases) is based on the
inerting effect of the natural gas. Due to the flooding with extinguishing agent, the
volumetric fraction of oxygen in the protection zone decreases continually. The
oxygen supply of the fire is cut off, leading to a decrease of both the combustion
rate and the temperature at the seat of fire.
When the oxygen concentration is reduced below that, capable of supporting com-
bustion; or the temperature falls below the critical value of 500°C, the fire is extin-
guished. The direct heat absorption of the molecules is different in each natural
agent, therefore each extinguishing gas presents a different extinguishing effi-
ciency.
Nitrogen (N
2
), Argon (Ar) and Carbon Dioxide (CO
2
) have excellent environmental
properties and are considered among the so called “green agents” since they pre-
sent zero ozone depletion potential (ODP) N
2
and Ar have zero global warming po-
tential (GWP) and in the case of CO
2
this value is only 1. Additionally N
2
and Ar are
non-toxic gases.
Inert gases are chemically neutral, therefore they have an excellent extinguishing
efficiency with all three essential fire classes: Class A (solid matters), Class B
(flammable liquids) and Class C (combustible gases). Additionally N
2
and Ar are
electrically non-conductive, colorless, odorless and tasteless.
CO2 in extinguishing concentration is lethal for human beings, therefore not rec-
ommended for use in archives and libraries, where presence of people cannot
be excluded.
In all types of archives is a required condition, that the extinguishing agent to be
used be a residue free or so called “clean agent”. For this reason inert agents are
particularly suitable for the protection of any type of archives. They will reliably ex-
tinguish any type of fire (open flame or smoldering) without reacting or leaving any
type of residue.
Paper, board and other organic media produce two kinds of fires when they burn:
– Open flame fires (surface fires): Oxygen depletion of the inert gases quickly
puts the fire off. Inert gases are the most appropriated extinguishing agents to
be applied in open flame.
– Deep seated fires: The surface fire is already put off, but inside the matter is
still burning. Would an incoming draft of fresh air take place, then re-ignition