TM 55-1930-209-14&P-3
4-7.1
Pretreatment skid
4-7.1.1
Changing cartridge cage assembly (filter elements). Perform this procedure when the pressure difference
between media filter output pressure gauge P2 and cartridge filter assembly output pressure gauge P3 (Figure 3-1)
exceeds 12 psi, or when the CARTRIDGE FILTER OK light goes out. Changing the cartridge cage assembly (filter
elements) requires a minimum of three personnel and a bridge crane with a 2-ton hoist.
a.
Follow these preliminary procedures if HP pump diesel engine is operating:
(1) Close valve RO15 to prevent product water from flowing to drinking water tanks.
Open valves RO20 and RO21 to allow product water to flow directly overboard.
CAUTION
Do not immediately stop engine. Operating engine for 5 minutes at low idle
allows hot areas to cool and turbocharger to slow down while still maintaining oil
pressure on the turbine shaft.
(2) Gradually reduce HP pump diesel engine throttle setting to idle (Figure 3-3). Leave engine idling.
(3) Open throttling valve RO7.
(4) Stop coagulant and inhibitor pumps at control station (Figure 3-1) by setting ON/OFF switches to OFF.
(5) After HP pump diesel engine has been running at idle for about 5 minutes, stop engine by pushing in on
shutdown lever (Figure 3-3).
(6) Stop seawater pump by turning pump OFF/ON/START switch on control panel (Figure 3-1) to OFF.
b.
Remove cartridge cage assembly (filter elements) as follows:
NOTE
Item numbers referenced in these procedures are shown in Figure 4-1.
Valves, shown in Figure 1-2, figure 1-3, and figure 1-5, are listed in Table 1-3.
(1)
Turn valve RO4 to position C (OFF) to prevent seawater flow to cartridge filter assembly.
(2)
Drain cartridge filter assembly by opening valve RO8.
(3)
Disconnect camlock coupling, item 3, on cartridge filter assembly output line.
(4)
Remove four hex nuts, item 4, on top end assembly, item 1.
WARNING
Do NOT manhandle heavy components. Operate bridge crane
according to TM 55-1930-209-14&P-13.
(5)
Using bridge crane and 2-ton hoist, remove top end assembly from the filter housing, item 2, and place it
out of the immediate work area.
(6)
Attach a lifting rig to the U-bolts, item 10, of cartridge cage assembly, item 9.
CAUTION
Cartridge cage assembly must be lifted vertically and slowly to prevent damage to
assembly. Two crewmen should slightly rotate cartridge cage assembly to
overcome O-ring resistance while the hoist applies a steady lift.
4-8
