12 May 2003
Including change 1, 19 January 2007
Drives. As defined by NFPA 20, fire pumps may be driven entirely by
electric motors if either a single reliable power source is available, or if two independent
power sources are available. Single reliable power sources need not include dual
substations or starting equipment. If the above conditions for use of "electric drive only"
cannot be met, design the system such that a minimum of 50 percent of pumping
capacity is driven by approved alternative drives such as diesel engines. Portable or
mobile pumping equipment is normally driven by remote-starting electric motors (when
appropriate) or by diesel or gas-turbine engines.
Pressure Control. Pressure must be controlled under varying demands
by staging of pumps and by incorporation of surge tanks and/or other suitable
equipment. It is imperative to prevent excessive surges due to starting and stopping of
pumps. Use a small pressure-maintenance pump to handle low flows. Fire pumps
must be equipped for automatic startup upon pressure drop, manual stop, and provision
for "manual override startup".
Alternative Pump Drive. When a separate cooling/flushing water system
is used, a variable speed electric drive may be used to control pressure. Variable
speed equipment may also be used for combined fire protection and cooling/flushing
systems when approved by the cognizant NAVFAC EFD/EFA OR USACE DISTRICT.
Variable speed drive equipment should be selected from types that have been proven
by successful use. Adjustable frequency type variable speed systems are preferred
because of their higher efficiency. See MIL-HDBK 1004/4, Electrical Utilization
Systems, for additional requirements regarding variable speed systems.
Location. Permanent pumping equipment for individual piers, wharves,
or drydocks should be located ashore and as near as possible to the pier, wharf or
drydock. It is highly preferred to provide vertical pumps with wet sump/intake
configuration. Where this is impractical, then the pumps may be placed in an enclosure
on or alongside a pier or wharf. The pump columns must be adequately protected from
wave action and floating debris. Portable or mobile pumping equipment may also be
placed on pier decks or on floating platforms moored to the pier.
Materials. Care must be taken when specifying pump materials for
nonpotable water service. Where salt or brackish waters are present, the potential for
galvanic and crevice corrosion is severe. Steel and cast iron, ordinary brass and
bronze, and most stainless steels are not suitable for these corrosive water sources.
Specially coated steel and cast iron as well as 400 series stainless steel have proven to
be ineffective. Material selection should be based on a thorough investigation of the
site and operational conditions. The construction specifications should be explicit as to
materials required for each major part, indicating appropriate ASTM designation and
it is impractical
to list all parts,
a sentence such
following should be included:
"Minor parts not listed should be of comparable materials with equivalent