ARGOSYSTEM uses argon as an extinguishing gas: argon
acts on the fire by decreasing the percentage of oxygen from 20.9% to
below 15%, which is theoretically the threshold below which the fire
should go out. The saturation principle used is of the total flooding
type. Therefore, the physical characteristics of the premises to be
protected become extremely important, so much so in fact, that the UNI
10877 standard requires a tightness test (or better, a calculation of
leaks) in order for an extremely accurate and reliable design to be
elaborated.
Argon is an inert gas which humans breathe from birth
because a very small percentage is present in the air. Its toxicity has
been carefully studied and the norm provides for the following:
Lowest Observable Adverse Effects Level (LOAEL): The
lowest concentration at which an adverse toxicological or physiological
effect has been observed. 52% Argon which corresponds to 10% oxygen.
No Observed Adverse Effects Level (NOAEL): The highest
concentration at which no adverse toxicological or physiological effect
has been observed. 43% Argon which corresponds to 12% oxygen.
Basically, the oxygen concentration will have to:
- drop below 15% to extinguish the fire;
- not drop below 12% to allow human presence inside the protected area;
- if it drops to between 12 and 10%, discharge delay devices will have to be installed;
- visual and acoustic alarms at the exits.
Total flooding extinguishing systems are used mainly to
ensure protection against risks arising in casings or appliances, for
which it is possible to identify a protected volume to contain the
extinguishing agent. They are
therefore ideally suited to extinguish various types of fires:
- Risks relating to electrical and electronic systems;
- For the protection of spaces in underfloors and suspended ceilings;
- Risks relating to flammable and combustible liquids and gases;
- High-value immovable property (museums, libraries);
- In areas with expensive machines and appliances (CED, control rooms).
In areas that are protected by total flooding systems
which may be occupied by people, the following safety criteria are
applied
- Time delays;
- Manual/automatic switches and cut-off devices;
- Emergency exits, emergency lighting and direction signs;
- Self-closing doors opening towards the outside;
- Visual and acoustic alarms at the exits.
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