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 TB 740-97-4
metal screws, spaced approximately 2 feet apart. The forward winch cover will be provided with two holes to introduce the
dehumidified air ducts: One hole for the humidistat cable; and another to mount a sensing element. The after winch cover will have
two holes for the dehumidified air ducts and one for a sensing element. Apertures between the coaming and the deck and all other
joints and seams will be sealed with strippable coating and bituminous coating.
(d) Sealing of 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 joints and seams will be similarly sealed.
(4) Dehumidification installation.
(a) Dehumidification system No. 1. A package dehumidifier, single desiccant bed, absorbent type, 10,000 cubic foot capacity,
110-volt, alternating-current, will be installed, generally, as shown on figure 47. The machine will be mounted on a stand and
protected with a cover, fabricated in accordance with figure 49. An extension, terminating in a 90 elbow, will be fitted to the
reactivation air outlet on the dehumidification machine in order to extend the outlet beyond the exterior side of the sheet metal cover.
The elbow will be turned away from the reactivation air inlet side and turned downward 45to prevent the direct entry of water. Four-
inch-diameter, No. 26 gage, galvanized sheet metal ducts, with necessary fittings and connections, will be installed, generally, as
shown on figure 47. The blank in the port side machinery house doorway will be provided with four holes: Two for the entrance of
the air ducts; one for the mounting of a sensing element contact; and the fourth for the passage of the humidistat cable. A flexible
hose, conforming to MIL-Spec H-8796, will be run from the moist air return fitting in the doorway blank and will terminate
approximately 3 feet from the after starboard side bulkhead of the machinery house and no more than 18 inches from the deckplates.
A humidistat, electronic-type, will be set to maintain a 40-percent relative humidity, plus or minus 5 percent, within the dehumidified
area. The humidistat will be installed approximately 3 feet above the floorplate and approximately 3 feet from the intake end of the
flexible hose. The humidistat will be mounted so that it is protected against movement or damage. A humidity sensing element, with
6-foot cable, will be installed in the machinery house. The element will be secured on the port side as far aft as the cable permits and
the contact will be installed in the hole provided in the doorway blank. The sensing element will be secured against movement and
against contact with metal or other conducting surfaces.
(b) Dehumidification system No. 2. A package dehumidifier, similar to and similarly mounted as specified for system No. 1,
will be installed, generally, as shown on figure 48. Ductwork, similar in size to that specified for system No. 1, will be installed,
generally, as shown on figure 48. The dryair connection from the machine will enter the starboard side of the aft winch cover.
Ductwork will carry the air from the portside of the aft cover to the port side of the forward winch cover. The return air will then be
withdrawn from the starboard side of the forward cover and carried back to the moist air connection on the dehumidification machine.
A humidistat, similar to that specified for system No. 1, will be installed In the forward winch cover. The humidistat will be secured
near the winch motor. A humidity sensing element, without cable, will be installed in the forward winch cover.
(c) Duct connections. Connections of air ducts to the dehumidification machines will be made by unions or slip joint
connections, which permit easy removal of the machines for servicing.
(d) Ductwork supports. Ductwork run on deck will be supported on wood or metal stanchions. The ducts will be secured to
the stanchions by strapping.
(e) Humidistat connections. Rubber covered electrical cable, with suitable terminal connections, will be installed to connect
the humidistats to the dehumidification machine. The manufacturer's instructions will be followed in making electrical connections.
Provisions will be made to prevent movement of the cables at the points where they leave the dehumidified areas.
Change 2 N-2
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