TM 55-1930-209-14&P-2
3-3.8
Seachest blowdown. Seachest blowdown is needed when gauges on input side of seawater strainers indicate a
significant drop in water pressure. Blockage should be eliminated by using the following procedures. If compressed air is
not available, start and operate the compressed air system in accordance with TM 55-1930-209-14 & P-7.
3-3.8.1 Forward seachest blowdown (serving ROWPU, chlorination, air conditioning, and ballast seawater
systems)
CAUTION
Before starting forward seachest blowdown, make sure seawater cooling water
pumps are not in use.
a.
Isolate seachest by closing valves SW1 and SW2. Make sure cooling pump is off. Close valve SW3.
b.
Check that compressed air pressure regulator 1 is set to 40 psi as shown on regulator gauge.
c.
Blowdown seachest on Barge 1 as follows:
(1)
Position valve SW30 to position B so compressed air flows into seawater seachest.
(2)
When air pressure regulator gauge reading stabilizes at 3-5 psi, position valve SW30 to position
A to allow seachest to vent.
(3)
Proceed to step e.
d.
Blowdown seachest on Barges 2 and 3 as follows:
(1)
Close valve SW30.
(2)
Open compressed air seawater seachest blowdown valve.
(3)
When air pressure regulator gauge reading stabilizes at 3-5 psi, close compressed air seawater
seachest valve and open valve SW30 to vent seachest.
WARNING
Do not open seachest valves SW1, SW2, or SW3 unless valve SW30 is positioned
to allow seachest to vent.
e.
To return seachest to normal operation, open valves SW1, SW2, and SW3, and turn on cooling pump and
seawater pumps as needed.
f.
If sea strainer inlet gauges do not indicate near normal reading, repeat steps a through e.
3-3.8.2 Aft seachest blowdown (serving generator cooling seawater system)
CAUTION
Before starting aft seachest blowdown, make sure generator sets are not operating.
a.
Isolate generator cooling seawater seachest by closing seawater valve SW37. Make sure all generators
are shut down and not pulling seawater from seachest.
b.
Check that compressed air pressure regulator 2 is set to 40 psi as shown on regulator gauge.
c.
Close seawater valve SW44.
d.
Open generator cooling seachest blowdown valve in aft port corner of ROWPU space.
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