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|  MIL-D-18641F(SH)
3.14.23 Vents and drains. Vents and drains shall be provided in each component as required.
Low points in integral piping which will not drain when the distillation unit is shut down shall be
provided with a plugged drain so that they may be drained when the ship is secured and unheated.
3.14.24 Cathodic protection Readily replaceable zinc anodes in accordance with MIL-A-19521
shall be installed in the salt water circuits of all heat exchangers of the distillation units except the
evaporating shells in accordance with the following:
For submarine submergence pressure applications, threaded support plugs shall not be
a.
used. Cover plates secured by four or more threaded fasteners shall be used for support
of anodes.
b. For submarine non-submergence pressure applications, bolted rover plates or threaded
plugs shall be used for support of anodes. If used, threaded plugs shall conform to
Drawing 803-5959186.
For surface ship applications, support plugs shall be of the straight thread O-ring seal
c.
type in accordance with MIL-A-19521. In exception to the material requirements of
MIL-A-19521, plug materials shall conform to the following:
Nickel-copper alloy
QQ-N-281 or ASTM B 164
70-30 Copper-nickel alloy
MIL-C-15726 or alloy 715 of ASTM B 151
3.14.25 Air ejector assemblies. The air ejector assembly furnished with the distillation unit
shall conform to type II of MIL-E-15465. The class shall be the same as specified for the
distillation unit, except for saturated steam propelled ships the air ejector assemblies shall be
class 3. Only one air ejector is required. Furnishing of a single or two stage air ejector unit shall
be determined by the distillation unit manufacturer as best fitting the vacuum requirements of the
distillation unit. A two stage air ejector shall be of the type which does not require an inter-
condenser. The air ejector steam pressure and temperature shall be as specified (see 6.2).
3.14.25.1 Oversized air ejectors. Oversized air ejectors and their after condenser shall not be
provided for the purpose of obtaining extra feed heating by using the high pressure air ejector
motive steam and thus decreasing the number of stages or effects or the size of the evaporators
or the salt water heater which uses low pressure auxiliary exhaust steam.
3.14.25.2 Check valve A check valve shall be provided in the air off-take line between the
distiller or stage condenser and the air inlet of the air ejector, or at the discharge of the air
ejector, to prevent loss of vacuum in the condenser due to sudden fluctuations in the steam supply
to the air ejector.
3.14253 Nozzles. Nozzles for units constructed with multi-stage air ejectors shall not be
interchangeable.
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