The required grade of filtration is 10µmeter. The ΔP across the filter cartridge should be limited to
1.5bar. Minimum water supply pressure through the filter system should not be less than 2.5bar and
max. 5.4bar.
Emergency back-up system 3.13
In case of loss of power from the main supply and pressure drop under 5bar, the emergency back-up
system (cylinder unit) shall be capable of supplying the required pressure to the most remote nozzle in
the system, until emergency power is available for the pumping system, or not less than 1 minute of
operation. The capacity of the emergency back-up system shall contain the amount of water (H
2
O) to
cover the largest section of nozzles for 1
minute at the design pressure.
Nitrogen (N
2
) is used as prime mover of the
water for immediate operation in case of
pressure drop and power failure in a fire
situation. The (N
2
) is supplied in standard gas
cylinders at a filling pressure of about 200bar.
A pressure regulating device is mounted on the
(N
2
) cylinder bank in order to maintain the
system pressure at its pre-set value.
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