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 TB 740-97-4
(b) Dehumidification piping system . The connecting points of all air ducts to areas being dehumidified will be
sealed with strippable coating and bituminous coating. The sealing will be carried over and around flanges, adapters, and other
devices used to attach or introduce the ducts. All seams in the ducts will be similarly sealed.
(c) Cargo tank sheet metal manhole covers. All joints and seams in the covers and apertures between the
coaming and the deck will be sealed with strippable coating and bituminous coating.
(d) Exhaust system. Openings in the muffler and exhaust piping outside the machinery house will be closed with
blanks, plugs, or pressure sensitive tape and sealed with strippable coating and bituminous coating.
(4) Installation of dehumidification systems . Four dynamic dehumidification systems (No. 1, 2, 3, and 4) will be installed
for eight cargo tanks. One dynamic dehumidification system (No. 5) will be installed for the engine room.
(a) Dehumidification systems No. 1, 2, 3, and 4. Install four package dehumidifiers, single desiccant bed absorbent
type, 10,000 cubic foot capacity, 110-volt, alternating current, as shown on figure 30. The machine will be mounted on stands and
protected with covers fabricated in accordance with figure 32. One machine will dehumidify two cargo tanks. The machine will be
installed between the port and starboard manholes and connected to all manholes in accordance with figure 30. Dehumidified air will
be circulated through all manholes by means of 4 inch galvanized metal duct. Connect two lengths of 4-inch flexible hose,
conforming to MIL Spec H-8796, inside each tank to carry air to the lower extremities of the tanks. Install four hair type humidistats,
one in each starboard tank, in accordance with figure 30. The humidistats will be set to maintain a 40 percent relative humidity, plus
or minus 5 percent, within the dehumidified area. Secure the humidistats to the dehumidification machines with lengths of No. 18
two-conductor, rubber-covered cable with suitable terminal connectors. Install one sensing element with six foot cable in the metal
blank over each manhole in accordance with figure 30. Duct work run on deck will be supported on wood or metal stanchions The
ducts will be fastened to the stanchions by galvanized strapping secured to the stanchions.
(b) Dehumidification system No. 5. A package dehumidifier, similar to and similarly mounted as specified for
systems 1, 2, 3, and 4, will be installed as shown on figures 31 and 31-Continued. One machine will be used to dehumidify the
engine rooms of from two to four barges. Four-inch diameter, No. 26 gauge galvanized sheet metal ducts, with necessary ells,
reducing fittings, and connections, will be installed as shown on figure 31 and 31 Continued. Suitable penetrations large enough to
permit the introduction of air ducts and the mounting of a sensing element in one block will be provided in the port and starboard
bulkheads of the machinery house of each barge. The air from the dehumidification machine will enter one side of the machinery
house bulkhead and will be removed from the opposite side. The connecting ducts between the barges will be flexible hose
conforming to MIL Spec H-8796. The flexible hose will be at least four feet longer than the distance between terminal connections.
Connections of ducts to the dehumidification machine will be made with unions or slip joint connections which permit easy removal of
machine for servicing. A hair type humidistat will be set to maintain a 40 percent relative humidity, plus or minus 5 percent, within
the dehumidified area. The humidistat will be installed in the machinery house of the barge from which the moist air return duct goes
directly to the dehumidification machine. The humidistat will be connected to the dehumidification machine with No. 18 two-
conductor, rubber-covered cable with suitable terminal connectors. Humidity sensing elements, with cable will be installed generally
as shown on figure 31 or 31-Continued. One sensing element will be mounted in the blank used for introduction of the moist air
return ducts on each barge.
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