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|  MIL-P-18472G(SH)
Class D-1 and D-2 pumps.
3.3.2.1
3.3.2.1.1 Continuous operation. Class D-1 and D-2 pumps shall be capable
of continuous operation over the entire range of specified fluid temperatures
(see 6.2) with suction head equal to the saturation pressure of the fluid plus
the specified submergence (see 6.2). Except for submarine applications, class
D-1 and D-2 pumps shall operate continuously under submergence control.
3.3.2.1.2 High capacity. Class D-1 and D-2 pumps of 40 gallons per minute
or more capacity shall have a constantly rising head-capacity characteristic
curve such that at constant rated speed, the total head at shutoff is at least 15
percent in excess of the total head at rated capacity.
3.3.2.1.3 Low capacity. Class D-1 and D-2 pumps of less than 40 gallons
per minute capacity shall have a constantly rising head-capacity characteristic
tune at constant rated speed. For pumps having capacities in the range of 20
to 40 gallons per minute, the total head at shutoff shall be at least 5 percent
in excess of the total head at rated capacity.
3.3.2.2 Class E pumps.
3.3.2.2.1 Capacity. Class E pumps shall have a constantly rising head-
capacity characteristic tune such that the total head at shutoff is at least 10
percent above total head at rated capacity. At constant rated speed, class E
pumps shall develop 120 percent rated capacity at a total head of not less than
80 percent of the rated total head.
3.3.2.2.2 Series operation. Class E pumps shall operate in series with
pumps in accordance with MIL-P-17881 or MIL-P-22302 and shall operate in parallel
without surging under all conditions of operation from shutoff to full capacity.
3.3.3 Casings.
3.3.3.1 Horizontal pumps. The casings of all horizontal pumps, except
close-coupled pumps, shall be split horizontally at the centerline to permit
ready removal of the rotors and replacement of bearings and glands.
3.3.3.2 Vertical pumps. The casings of all vertical pumps, except close-
coupled or barrel type pumps, shall be split vertically in such a manner as to
allow removal of the rotor without disturbing the pump on its foundation, the
piping thereto, or the driving unit.
3.3.3.3 Work access. Clearance shall be provided around bolt heads and
nuts to permit the use of ordinary tools. Ordinary tools are tools which are
available in the Federal Supply Catalog.
(Copies of this catalog may be
consulted in the office of the DCASMA.)
3.3.3.4 Assembly alig nment.
Fitted bolts or dowel pins shall ensure main-
tenance of alignment in assembly. Dowel pins shall be corrosion-resistant,
shall have a threaded end and nut design, and shall be secured against coming
adrift under shock loading.
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