line between the high-pressure manifold and the high-pressure pump discharge gate. For VdS, FM
Global, and marine SEM-SAFE
®
High-Pressure Water Mist Pump Units, one single large capacity
pressure relief valve is used for the complete unit. The pressure relief valve is pre-set at the factory
acceptance test, and this setting should not be altered. Any service or repair of the valve should be
carried out by a service engineer.
System pressure transmitter
The system pressure transmitter has the following functions:
Displaying the actual system pressure in the alarm
display on the Unit Control Panel (UCP)
Start of the pilot pump or re-charge of pressure level at
system pressure of ca. <10bar
Stop of the pilot pump at system pressure of ca. >14bar
(Land applications) or ca. >12bar (Marine applications)
Initiating the high-pressure pump start sequence at
pressure level of less than 6bar (Land application) or
less than 10bar for more than 10 seconds (Marine
application)
The system pressure transmitter is monitored for wire break and short circuit. Wire break in the
cabling will not cause pump start.
Pressure switch
The 6 bar pressure switch is back-up for the system pressure transmitter used in Land applications
in order to secure monitoring of the system pressure, in case the system pressure transmitter has a
malfunction. The 6 bar pressure switch will activate the high-pressure pump starting sequence if
pressure is below 6 bar. A leak alarm is initiated if the pilot pump starts more than 2 times within 5
minutes
Filter system 3.12
In order to avoid contamination, clogging of water mist nozzles and malfunction of pumps and
valves, the extinguishing water has to be filtered before it is delivered into the SEM-SAFE
®
High-
Pressure Water Mist Pump Unit. On pump units with a unit tank, the filter is mounted before the
water supply reaches the tank. On pump units with a supply manifold, the filter is mounted before
the water supply reaches the supply manifold, under condition that it is going through the booster
pump beforehand. If there is no booster pump, the filter must be placed before the reservoir tank.
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