Recirculation - Centrifugal
pumps that will operate at or near shutoff during a
service condition shall have means for recirculation.
As a minimum, fire pumps, main sea water pumps, and
the science seawater pump shall be furnished with recirculation.
The amount of recirculation shall be sufficient to prevent
overheating of the pump when operating at shutoff and
to REV 03, 09-30-94 prevent vaporization of the liquid
being pumped. For additional recirculating piping details,
see the specifications for the piping system served
by the pump.
All centrifugal pumps
except for the science seawater pump shall be designed
and built in accordance with ASTM F998.
The science seawater
pump shall be of all titanium or GRP construction. If
a titanium pump is used it shall be provided with ASTM
B367 titanium casing, impeller and wearing rings and
a stainless steel shaft. If a GRP pump is used it shall
be built to ANSI/ASME B73.1M standards for chemical
process pump with all wetted parts corrosion resistant
and nonmetallic.
A science seawater
pump rated at 50 gpm shall supply seawater to three
manifolds in the Main Lab, two manifolds in the Wet
Lab, two manifolds in the Bio/Chem Analysis Lab, and
to sinks in the Science Staging Area, Climate Control
Chamber and each van position. The science seawater
pump shall also supply flow to a scintillation counter
and an automatic salinometer. The science seawater pump
shall take suction from a seachest which is as far forward
as possible but not less than 30 percent of the ship's
length aft of the forward perpendicular.
MOD A00023 (FMR-7) REV 03, 09-30-94
MOD A00109 (FMR-29) REV 12, 10-31-97
MOD A00112 (FMR-31) MOD A00114 (FMR-30)
An all-titanium or GRP simplex strainer with 3/16-inch
basket perforations shall be installed at the pump suction.
Total clear area of the basket perforations shall be
not less than four times the area of the strainer discharge
connection.
The science seawater
pump and its associated piping shall be arranged and
insulated so that the seawater temperature does not
change by more than 0.3 degrees F when being pumped
from the sea chest to any service. An overboard bleed
line with automatic pressure control valve located in
the vicinity of the wet labs shall be provided to permit
maintaining supply main sea water velocity at not less
than eight feet per second to prevent marine growth
in the supply main under all seawater demand conditions.
Drains shall be provided to permit draining the entire
system, as well as individual branches when not in use,
to prevent marine growth.
The science seawater
pump shall have a local start-stop control and remote
start-stop control from one wet lab.
"Pump running"
indicator lights shall be provided at both sets of controls.
Suction vacuum/pressure
and discharge pressure gauges shall be installed at
the pump.
A digital temperature
sensing device, with display in ECC (see section 202),
shall be installed to obtain seawater temperature that
is not affected by cutter generated heat. This information
shall be supplied to the Science Data Network
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