Kidde Fire Systems Natura, Руководство пользователя

Страница: 12 / 32

General Information
June 2020 1-4 P/N 06-237620-001
• Natura IGS systems designed to concentrations between 52 and 62 percent (correspond-
ing to between 10 and 8 percent oxygen, sea level equivalent of oxygen) shall be permitted
given the following:
– The space is normally unoccupied
– Where personnel could possibly be exposed, means are provided to limit the exposure
to less than 30 seconds
• Natura IGS systems designed to concentrations above 62 percent (corresponding to 8 per-
cent oxygen or below, sea level equivalent of oxygen) shall be used only in unoccupied ar-
eas where personnel are not exposed to such oxygen depletion.
Note: The term "…sea level equivalent of oxygen…," used above, deserves some clarification.
The allowed exposure limit to air diluted with Natura IGS agents relates to the residual
oxygen concentration. At sea level the atmospheric pressure is 14.7 psi (101,325 Pa).
The sea level equivalent of oxygen is the "partial pressure" of oxygen in air when the
atmospheric pressure is 14.7 psi. The volume fraction of air that is oxygen is 0.21, or
21%. Thus, at sea level the partial pressure of oxygen in air is 3.09 psi (21,290 Pa).
Thus, the provisions outlined above can be summarized in as shown in Table 1-2.
https://en.wikipedia.org/
Table 1-2. Egress time limits for spaces flooded with an Natura IGS Agent
Agent Conc.
vol %
% O
2
at
Sea Level
P
O2
, psi
Allowed Occupancy
Egress Time
Limit
C < 43 %O
2
> 12 P
O2
> 1.78 Normally occupied 5 min
43 < C < 52 12 > %O
2
> 10 1.78 > P
O2
> 1.47 Normally occupied 3 min
52 < C < 62 10 > %O
2
> 8 1.47 > P
O2
> 1.18 Not normally occupied 30 s
C > 62 %O
2
< 8 P
O2
< 1.18 Unoccupied areas only n/a