Clean agent fire suppression systems are
used in enclosures where a sprinkler system
would cause damage to sensitive contents such
as computer servers, paper files or historical artifacts.
Upon fire detection the compressed clean agent (which
can be a halocarbon or an inert gas) is released into the
enclosure. Once the enclosure is totally flooded, the agent
will begin to leak out at a rate that primarily depends upon
leakage area in the lower part of the enclosure, although higher
leakages play a significant role as well.

his is due to the fact that most of the gaseous agents (except nitrogen)
are heavier than air. If the enclosure has leakages, the gas starts leaking
out from the enclosure and fresh air replaces the gas from above.

The gas suppression system is designed to protect critical systems
within the enclosure for a certain time once the agent is released, which
is called the ‘hold time’. This will generally be 10 minutes, or in some
cases 20 minutes or any other time frame dependent on the exact
situation and used standard. To keep the agent inside the enclosure,
the enclosure will have to be air tight enough to prevent agent from
leaking out too fast: the less leakage, the more hold time an
enclosure will have.

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