System description 2
General system description 2.1
The SEM SAFE
®
High-Pressure Water Mist System consists of nozzles, pipe work, section valves
and pump unit and can be classified as one of the following four different types of systems:
Wet Pipe Water Mist System
Dry Pipe Water Mist System
Pre-action Water Mist System
Deluge Water Mist System
The SEM SAFE
®
High-Pressure Water Mist Pump Unit can serve any combination of these four
systems.
General description of Wet Pipe Water Mist System 2.2
The wet system is a system using automatic nozzles attached to a piping system permanently filled
with water at maintained standby pressure. The system is activated when a thermal-sensitive glass
bulb in the automatic nozzle bursts, which is caused by an increase of the temperature at the nozzles
during fire. This creates a pressure drop in the system which activates the SEM SAFE
®
High-
Pressure Water Mist Pump Unit that immediately delivers water under high pressure to activated
water mist nozzle(s) located in the area of fire.
General description of Dry Pipe Water Mist System 2.3
Dry pipe water mist system is a system using automatic nozzles attached to piping system
containing air under standby pressure. Protected sections are separated from the supply sources by
dry pipe section valve(s). The system is activated when a thermal-sensitive glass bulb in the
automatic nozzle bursts, which is caused by an increase of the temperature at the nozzles during
fire. It allows the water pressure to open a dry pipe section valve. The water then flows into the
piping system and discharges through any activated water mist nozzles located in the area of fire.
General description of Pre-action Water Mist System 2.4
A pre-action water mist system is used where special precautions are required to avoid the water
mist being released unexpectedly in the protected rooms. It is using automatic nozzles attached to a
piping system containing air under standby pressure, with a supplemental detection system installed
in the same area at the water mist nozzles. The actuation of the detection system opens a valve that
allows water to flow into the piping system and discharge through any activated water mist nozzles.
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