MIL-P-17861F
3 5.2 Casing. The casing, including flanged-mounted air separation
chambers , if furnished, shall be cast iron or aluminum alloy in accordance with
the material specified (see 6.2), except that type IV pump casings shall be
furnished in aluminum alloy only. The casing shall be designed to withstand a
hydrostatic test pressure equal to 1.5 times the pump discharge pressure or the
total dynamic head, whichever is greater. The casing shall be equipped with a
priming port and means for readily draining the casing. A standard pipe tee and
plug installed on the discharge connection will be acceptable as a priming port
The casing shall be designed or equipped to prevent siphonage of priming'~fiid
on shutdown if a foot valve is not installed on the suction line. The pump
shall be equipped with a renewable wearing surface or surfaces, or impeller
adjustment so that proper clearances can be restored without the need for
replacing the pump casing. The casing shall be designed with bolted plates or
segmental sections to permit removal and replacement of internal pump
components .
3.5.3 Impeller. The impeller shall be of the material specified (see 6.2).
Imperllers shall be open or semi-open. Impellers shall be cast in one piece,
balanced, and shall be keyed or screwed to the shaft in a manner to provide
positive locking against any rotative loosening effect.
3.5.4 Bearings. Pumps with separate shafts coupled to the engine crankshaft
shall be equipped with not less than two sets of ball or roller anti-friction
bearings to support the shaft. The bearing shall be rated to withstand
continuous radial or axial loading due to Inherent rotational forces and
hydraulic imbalance. The bearings shall have adequate provisions for
lubrication and shall be sealed against the entrance of dirt and water.
3-5-5 Shaft seal. The shaft seal shall be of the mechanical type and shall
be self-lubricated, oil lubricated, or grease lubricated. The seal shall
consist of a rotating element, a stationary element, a spring, and any
additional elements common to particular seal designs, such as a diaphragm,
bellows, spring cage, or grease cup. Stationary elements shall be fabricated of
a hard, wear-resistant ceramic or brass material, or of nickel-bearing cast
iron. On self-lubricated seals, the rotating wearing surface shall be carbon or
a material having similar low-friction properties. Seal springs shall be
stainless steel. Grease cups shall be of the spring-loaded type designed to
automatically feed lubricant to the seal as required.
3.5.6 Connections. The connection sizes for the suction opening shall be of
the same nominal pipe size as the discharge opening. The openings shall be
tapped or fitted to provide female tapered pipe connections in accordance with
ASME B 1.20.1. Both connections shall be so located or fitted that a
direct-connected length of straight pipe shall extend in a horizontal direction.
3.5.6.1 Optional connections. When specified (see 6.2), the pumps shall be
fitted in accordance with one of the following options:
Option 1: Four inch and larger pipes size pumps shall be equipped
a.
with standard class 125 pound (lb) cast iron flanges, conforming to
ASME B 16.1, or class 150 lb steel flanges, conforming to
ASME B 16.5, as specified (see 6.2).
8
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