Pump unit operation 4
Pump unit activation 4.1
With the SEM-SAFE
®
High-Pressure Water Mist Pump Unit in stand-by mode (pilot pressure
maintained at 10-14 bar), activation of one or more water mist nozzles causes a sharp pressure drop
in the system. The pressure drop and increasing water demand is monitored by the system pressure
transmitter which at pressure below 6 bar creates a start signal initiating the high-pressure pump’s
start sequence.
The system will not activate in the case of an error on the cable to the pressure transmitter. In case
of short circuit or wire break on the pressure transmitter, the back-up pressure switch initiates the
pump start sequence.
The high-pressure pump start sequence can be also initiated manually by pressing the “Pump start”
push button placed on the Unit Control Panel front. Then the sequence is initiated as for an automatic
start. The high-pressure pumps can also be individually started at the Unit Control Panel by operating
the dedicated key switch located in the Unit Control Panel front.
Increasing discharge capacity in a fire situation 4.2
Activation of more nozzles and thereby increasing water demand is monitored by the system
pressure transmitter. If system pressure drops below 100 bar for 5 sec., the next high-pressure pump
in the start sequence is started and is adding its capacity to the pump unit discharge capacity. The
same procedure is used for the remaining number of pumps in the start sequence until the design
capacity has been achieved.
If the pressure has been above 100 bar for more than 10 minutes, the last started high-pressure
pump is stopped automatically, but re-started again if the pressure is below 100 bar for 5 sec. The
first started high-pressure pump can only be stopped by activating the emergency stop push button.
Shut-down of pump unit after activation (fire suppression) 4.3
SEM-SAFE
®
High-Pressure Water Mist Pump Unit will operate until it is stopped manually. Stop of
the pump unit after activation shall only be ordered by the responsible leader of the firefighting
team. The SEM-SAFE
®
High-Pressure Water Mist Pump Unit should only be stopped by the direct
orders of the fire brigade commander.
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