shaft type to allow the pump shaft to pass
concentrically through the reducer and motor
allowing finite impeller elevation adjustments.
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Impeller shaft shall be stainless steel and intermediate shaft(s) shall be
[cold-rolled carbon steel][same material as impeller shaft]. Design
shafting so that [shaft sections shall not exceed [_____] mm feet in length
and that] any necessary vertical adjustment of impeller can be made [from
operating room floor] without interfering with shaft alignment. Also
provide for removal of impeller from below without disassembly of pump
above impeller bowl. If pump is multi-staged, design to permit the lower
bowls and impeller to be easily removed for in-place inspections of upper
propeller and bowl. Design shafts for two different design cases. The
first uses a factor of safety of 5 based on ultimate tensile strength of
shaft material and rated wattage horsepower of [motor] [engine]. The
second uses 75 percent of the yield strength of shaft material and [locked
rotor torque of motor] [maximum wattage horsepower of engine].
2.2.9.2
Couplings
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NOTE: Rigid flange couplings should be specified
only for pumps having discharge diameters greater
than 1800 mm (72 in.). The rigid flange coupling
may be specified as an option for all pumps less
than 1800 mm (72 in.). Sleeve type couplings should
be used for pumps having discharge diameters from
600 mm (24 in.) to 2100 mm (84 in.). Threaded shaft
couplings can be used for pumps with discharge
diameters less than 600 mm (24 in.).
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Pump and [motor][gear reducer] shafts[ and pump shaft sections] shall be
coupled together using rigid flanged coupling capable of transmitting the
forces and torques involved. Coupling halves shall be bolted together and
shall be maintained concentric with each other, by means of a rabbet fit,
to within 500 m 0.002 inch. Shaft coupling nut, if used, shall be
retained by fitted bolts, and all tolerances specified for the coupling
shall apply. Finish machine the flange and bore in one setup to insure
that flange of coupling shall be true to the bore. Flange shall be
perpendicular to the bore, and parallel to the opposite end and mating
flanges to within 500 m 0.002 inch. Flange shall be concentric to
centerline of shaft to within 0.50 mm 0.002 inch.[ Pump shaft sections
shall be joined together with [sleeve-type couplings capable of taking
rotation in either direction. Threads, except on fasteners, shall not be
employed in construction of sleeve-type couplings][threaded couplings in
which the threaded shaft ends are threaded into the coupling].] Couplings,
including keys and fasteners, shall be constructed of stainless steel
materials. The finished shaft assembly shall be concentric about shaft
centerline to within 100 m 0.004 inch. Shop assemble couplings and pump
shaft and inspect for compliance with contract requirements. After
inspection, matchmark parts, including fitted bolts, to their mating pieces.
2.2.9.3
Journals
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NOTE: Select appropriate alternate paragraph.
Alternate 1 is used when plain steel shafting is
SECTION 15131A
Page 32
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