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Page Title:
Suction and discharge connections |
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|  MIL-P-18472G(SH)
Forcing bolts shall be provided for breaking
3.3.3.5 Forcing bolts.
joints.
3.3.3.6
Drains and vents. Casings of horizontal and vertical pumps shall
be fitted with drain and vent connections. Drain connections shall be in
accordance with MS16142 and MS18229 and shall permit complete drainage of the,
pump without disassembly of the pump. For vertical, bottom suction pumps, the
pump suction may seine as the drain. The casings of all close-coupled and barrel
type pumps shall permit ready replacement of wearing parts. Horizontal pumps
shall be fitted with vent connections on the discharge casings of each stage.
Pumps taking suction from vacuum shall be fitted with suction casing vent
connections , except pumps for vapor compression distilling units which shall be
self-venting.
3.3.3.7 Wearing rings. Pumps, except brine pumps with semi-open impellers,
shall be fitted with removable casing wearing rings. Diaphragms (interstage
pieces) in multi-stage pumps shall be fitted with bushings. For axially split
casings, the wearing rings shall be held by a double tongue and groove in the
fixed half casing, and a single tongue and groove in the removable half casing.
3.3.3.8 Gaskets. Pump casing joints shall be made up using compressed
sheet gaskets. For close-coupled and barrel type pumps, O-rings may be used to
make up casing joints. Gasket compression and tolerances shall not affect
bearing, bushing or wearing ring fits to an extent that will adversely affect
reliability and performance.
3.3.4 Suction and discharge connections.
Unless otherwise specified (see
6.2), 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.
3.3.4.1
Split case pumps. Suction and discharge connections of split case
pumps shall be
on the fixed half of casing, except on close-coupled pumps. In
special cases,
suction and discharge connections may be on the top or removable
half of casing
subject to specific approval by the design review agency.
3.3.5 Impellers. Impellers shall be of the closed type, except brine
pumps of 25 gallons per minute or less shall have semi-open impellers. Outside
surfaces shall be smooth finished. Impellers shall be keyed on the shaft and
securely held against axial movement by locked nuts or other means approved by
the design review agency.
3.3.5.1 Wearing rings. Impellers shall not be furnished with wearing
rings. 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 accom-
modate undersize casing wearing rings to restore design running clearance.
3.3.5.2 Balancing. Each impeller shall be dynamically balanced in
accordance with MIL-STD-167-1.
3.3.5.3 Diametral clearance. Diametral clearance shall be as specified in
table I.
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