4-7.2 Media filters. Media filters need to be backwashed and flushed when pressure difference between seawater pump
discharge pressure gauge P1 and media filters output pressure gauge P2 (Figure 3-1) exceeds 35 psig, when MEDIA
FILTER OK light (Figure 3-1) goes out, or when water sample taken from cartridge filter assembly drain valve ROE is
dirty Filtered water from two of the filters is used to backwash the third one In this procedure, a slow backwash Is
followed by a fast backwash followed by another slow backwash for each of the three media filters All three media filters
are then flushed simultaneously. Backwashing and flushing should normally take about 1 hour per ROWPU.
4-7.2.1 Preliminary procedures. If HP pump diesel engine is operating, perform the following- .
Close valve RO15 to prevent product water from flowing to drinking water tanks. Open valves R020 and
RO21 to allow product water to flow directly overboard.
Figure 4-3. Chemical Metering Pump Priming.
Do not immediately stop engine. Operating engine for 5 minutes at low idle allows hot areas to
cool and turbo-charger to slow down while maintaining oil pressure on the turbine shaft.
Gradually reduce HP pump diesel engine throttle setting to idle (Figure 3-2). Leave engine Idling.
Open throttling valve RO7.
Stop coagulant pump and Inhibitor pump at control station by setting ON/OFF switches (Figure 3-1) to OFF.
After HP pump diesel engine has been running at idle for about 5 minutes, stop engine by pushing in on
shutdown lever (Figure 3-2).
Stop seawater pump by turning pump OFF/ON/START switch on control station (Figure 3-1) to OFF.