Kidde Fire Protection 400 Series, Design, Installation, Operation, And Maintenance Manual

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General Information
July 2018 1-4 06-237518-001
Note: These instructions do not apply to personnel remaining in the enclosure after system
release during a fire if they are properly trained and equipped with self contained
breathing apparatus.
1-3.2 Agent Safety Concentrations
Kidde IGS agents are used at relatively high concentrations to extinguish fires, typically in the
range of 40 to 50% agent in air, or more. At a Kidde IGS agent concentration of 45%, the
residual oxygen concentration is 11.5%, compared with 21% in normal air. The principal health
risk from exposure to atmospheres having such low oxygen concentrations is “hypoxia,”
meaning insufficient oxygen concentration in the blood. The resulting guidelines for exposures
to atmospheres flooded with Kidde IGS agents are as follows:
•
Unnecessary exposure to Kidde IGS agent resulting in low oxygen atmospheres shall be
avoided.
• The maximum exposure time in any case shall not exceed 5 minutes. See NFPA 2001 2015
Edition, table 5.5.3.3 for atmospheric correction factors that shall be considered when de-
termining the design concentrations.
• For systems that must meet NFPA standards, a pre-discharge alarm and time delay shall
be provided in accordance with the provisions of NFPA 2001, 2015 Edition.
• Unprotected personnel shall not enter the area during or after Agent discharge.
The following additional provisions shall apply:
•
Kidde IGS designed to concentrations below 43 percent (corresponding to an oxygen con-
centration of 12 percent, sea level equivalent of oxygen) shall be permitted where means
are provided to limit exposure to no longer than 5 minutes.
• Kidde IGS designed to concentrations between 43 and 52 percent (corresponding to be-
tween 12 and 10 percent oxygen, sea level equivalent of oxygen) shall be permitted where
means are provided to limit exposure to no longer than 3 minutes.
• Kidde IGS designed to concentrations between 52 and 62 percent (corresponding to be-
tween 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
• Kidde IGS designed to concentrations above 62 percent (corresponding to 8 percent oxy-
gen or below, sea level equivalent of oxygen) shall be used only in unoccupied areas 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 Kidde 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.
CAUTION
During discharge, the agent passing through the system nozzles can emit a
noise at a level which could cause hearing injury.
CAUTION
Direct contact with the agent during discharge can cause frostbite burns to the
skin.