MIL-HDBK-1005/7A
than 2 hours per day, a series of fixed screens can be used.
Follow the sequence and sizes of bar, coarse, and fine screens
as given in Section 6. Framing and screening should be heavy,
hot-dipped galvanized steel, corrosion -resistant alloy, or
fiberglass when screens are not exposed to sunlight. Provide
easy access for cleaning and maintenance.
4.7.5
Pumping . System pressure and capacity are determined
by fire, flushing and cooling water requirements. The basic
criteria for pumping stations are identical with those for fresh
water stations given in Section 5 and Section 9 of this manual,
except as discussed below.
4.7.5.1
Power. Steam turbine drives can be used if the pump
station is in, or adjacent to, a central heating plant or power
plant that uses steam-driven auxiliaries. Power must be
available at all times. Where the seawater system is a main
source of firefighting water, provisions should be made for
either standby power or auxiliary drive by diesel power.
Standby power or auxiliary drive units should be automatically
supervised and thrown into operation, unless the pumping station
is to be manned continuously.
4.7.5.2
Pumps. The use of cast iron for pumps, other than
standby pumps, is prohibited for saltwater systems. Pump
suppliers can be consulted for recommended materials based on
service and pressure. However, designers should evaluate the
corrosivity of the water and specify appropriate materials.
Easy dismantling is essential for this type of service.
Capacity of the standby power system or auxiliary drive system
should provide at least 50 percent of the total pumping
capacity, unless electric power is provided from two separate
sources.
4.7.5.3
Alarms. Where the system will be in continuous
service, provide low pressure alarms. If the pumps operate
intermittently, the alarm system should be operative only when
driving units operate, after a suitable time delay.
4.7.6
Distribution System. Use applicable criteria for
potable water systems, Section 7. Include additional loops and
branches required for graving docks and waterfront operational
facilities.
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