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Page Title:
Suction and discharge connections. |
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|  MIL-P-18682D(SH)
3.3.4 Suction and discharge connections.
3.3.4.1 Unless otherwise specified (see 6.2.1), suction and discharge
connections shall be flanged for mating with flanges in accordance with
MIL-STD-777 or MIL-STD-438 for the applicable system.
3.3.4.2 Suction and discharge connection of split case pumps shall be
on the fixed half of casing,
3.3.5 Impellers or propellers.
3.3.5.1 Outside surfaces of impellers shall be smooth finished.
3.3.5.2 Impellers shall be keyed on the shaft and securely held against
movement by locked nuts or other means.
3.3.5.3 Impellers, for type II and type III pumps, shall not be fitted with
wearing rings. The impeller hub wearing surfaces shall have material thickness
to permit reducing the diameter of the impeller hubs by as much as 0.050 inch to
accommodate undersize casing rings to restore design running clearances.
3.3.5.4 Each impeller shall be dynamically balanced in accordance with
MIL-STD-167-1 .
3.3.5.5 O-rings and gaskets are prohibited from being in contact with
highly-alloyed corrosion resistant steel parts.
3.3.6 Shafts.
3.3.6.1 Shaft threading, except threading for rolling contact bearing
lock nuts, shall be counter to the direction of rotation. Shaft threading for
rolling contact bearing lock nuts may be clockwise or counterclockwise.
3.3.6.2 The shaft (pump or driver) except those driven by a.c. motors,
shall be provided with means to permit the ready and direct use of portable
tachometers. When this is impracticable, provision shall be made for the
use of a portable tachometer on the shaft of the driver.
3.3.6.3 Shafts shall be fitted with shaft sleeves in way of all wearing
surfaces, such as stuffing boxes, bushings, and water lubricated bearings.
O-rings shall be installed between the shaft sleeve and shaft.
3.3.6.4 Shaft flingers shall be provided adjacent to the gland for all
pumps. The flinger shall be so located that leakage which might occur between
the gland shaft sleeve and the shaft, as well as from the gland, is not allowed
to reach pump or motor ball bearings. For rigid coupled units, the coupling may
serve as the pump flinger provided the coupling is constructed of corrosion-
resistant material.
3.3.6.5 A balance ring shall be located in the coupling area between the
lower motor bearing and the pump stuffing box, allowing sufficient clearance for
packing gland adjustment. The balancing ring shall include the features and
ounce-inch capacity specified in MIL-E-917 for submarine rotating equipment
balance rings.
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