 |
|||
|
|
|||
| ||||||||||
|
|  MIL-D-18641F(SH)
3.14.25.4 Steam chests. Air ejector steam chests for all units shall be manufactured of a 400
series stainless steel.
3.1425.5 Test orifice A test orifice connection with orifice plate and cut-out valve shall be
installed in the air ejector suction piping. The test orifice connection shall be installed downstream
of the cut-out valve to allow a metered amount of air to the air ejector suction to check air ejector
performance.
3.14.26 Vacuum pump. When specified (see 6.2), the vacuum pump for types IV and V
distilling units shall be in accordance with MIL-V-18683. Pumps shall be single or multiple stage
as required by vacuum conditions.
3.14.26.1 Eductor. In lieu of the vacuum pump specified in 3.14.26, a water operated eductor
may be furnished. Materials shall be nickel-copper alloy for the eductor nozzle and bronze in
accordance with ASTM B 61 for the eductor body.
3.14.27 Flow meters. Flow meters shall be provided for each type I, III, or V distillation unit.
Meters for flow of feed or brine shall be of a construction which is not readily affected by scale
formation. In particular, meters equipped with a guide rod on which the float rides, or with an
indicating rod mounted on the float and extending through a guide or packing gland are not accep-
table. If method of feed is such that the ratio of feed and distillate must be controlled feed and
distillate meters shall be provided; otherwise, only a feed meter will be required.
3.14.27.1 Water meter. A distillate water meter shall be provided with each unit. Meter shall
conform to class B in accordance with MIL-M-2082, except that a magnetic drive shall be provided.
3.14.28 Distilling units for saturated steam propelled surface ships and submarines.
3.14.28.1 Submergence pressure. In submarines, the feed for the distilling unit will be reduced
from submergence pressure to that required by the feed circuit of the unit by means of a pressure
reducing valve furnished by the shipbuilder who will also furnish a relief valve to safeguard against
malfunction of the reducing valve. Any parts of the distilling unit located ahead of the reducing
valve and thus subjected to submergence pressure shall be constructed to withstand this pressure.
3.14.28.1.1 Heat exchangers. Heat exchangers of the shell and tube type provided as
components of the distillation unit for saturated steam propelled surface ships or submarines shall
be provided with two tube sheets at each end, except when U-bent tubes are used, two tube sheets
shall be used at the inlet-outlet end. For straight tube bundle exchangers, the inner tube sheets
shall be welded to the shell. A space not less than 1/2 inch wide shall be provided between the
tube sheets by use of a spacer ring or by machining one face of one or both tube sheets. The
space shall be provided with a vent and drain to atmosphere. The joint between tube sheets or
between tube sheet and spacer shall be welded. The contractor shall be responsible for providing
the proper span of tubes between double tube sheets, so that the tubes will not be overstressed
due to radial expansion differentials of the double tube sheets (see 6.3 and appendix C).
29
|
|
Privacy Statement - Press Release - Copyright Information. - Contact Us |
Click
here for thousands of PDF manuals