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|  MIL-G-24477(SHIPS)
3.2.5.3.2 Fuel pump. The engine driven positive displacement fuel pump shall be
capable of lifting fuel up to 48 inches.
3.2.5.3.3 Filtration.
The fuel system shall be protected by a primary filter (strainer)
ahead of the engine mounted fuel pump and a duplex secondary filter ahead of the fuel injec-
tion pump or unit injectors. If the fuel system is of such a design that the filter must be
positioned on the suction side of the fuel pump, only the secondary filter is required.
Filters shall be constructed of brass, bronze, or other metals which are not readily cor-
roded by sea water contaminated fuels. Coated steel or untreated aluminum are not acceptable.
Filters shall include vents to permit the expulsion of air. Manually operated drain valves
shall be provided to completely drain the filter bodies without the use of tools.
3.2.5.3.3.1 Primary filter Primary filters (strainers) shall be the simplex metal
edge type with 0.003 to 0.0035inch spacing, enclosed manually operated cleaning device
and sediment drain. The term "metal edge" is defined as stacked metal discs or helically
wound flat metal wire or metal ribbon media. Wire cloth, screen, sintered metal or perfor-
ated plate media are not acceptable for simplex strainers.
3.2.5.3.2 Duplex secondary filters. Duplex filters shall consist of two filter units
connected to a common head equipped a three way plug valve and disposable filter elements.
The level operated valve shall direct the fuel flow through one side to permit element change
and cleaning of the other side without interruption of flow. Each side shall be sized to
accommodate the full flow of the engine fuel pump and employ drain valves to permit complete
draining. Filter elements and materials used for metal parts and gaskets shall be in accord-
ance with MIL-F-20627. Filter elements shall be rated at 150 gph in lieu of the 50 gph rating
stated in MIL-F-20627.
3.2.5.3.4 Fuel oil priming pump. A fuel oil pump to prime the engine fuel oil system
within 2 minutes at an ambient temperature of 70F. shall be furnished.
3.2.5.3.5 Fuel oil tank. The preferred Navy installation can be expected to provide,
by the use of a day or other arrangement, a positive head of fuel pressure on the engine
primary pump suction connection. The fuel systems of some engines may be so designed that
combustion space flooding would result when this positive head is applied during engine shut-
down.
In such cases, the engine supplier shall furnish all necessary devices, such as float
tanks, valves, etc., which he recommends to protect the engine and insure proper operation.
3.2.5.4 Lubricating system. Lubricating oil shall conform to symbol 9250 of MIL-L-9000
for ambient condition above 20F. The same grade or symbol number of lube oil shall be
used in the engine and attached accessories. Engines shall be provided with an oil level
indicator, filling opening and accessible sump drain connection or a sump pump to drain or
clean the engine oil pan. Bayonet type oil level indicators shall be shielded to permit
accurate readings while the engine is running. The lubricating oil system shall be arranged
as shown on figure 1. Engines shall be provided with suction and pressure connections for
priming and flushing the engine lubrication system.
3.2.5.4.1 Lubricating oil pumps.Pressure pumps, scavenging pumps and piston cooling
oil pumps shall be of positive displacement type, driven by the engine. The scavenging
pump capacity shall be approximately 1-1/4 times the capacity of the pressure pump and shall
scavenge the system from idle to rated speed. A relief valve shall be provided for the
outlet of each pump. If the pump suction incorporates a check valve, means shall be provided
to prevent excessive pressure build-up in the suction line in case the engine and pump are
rotated backwards.
3.2.5.4.2 Coolers. Lubricating oil coolers shall conform to MIL-C-15730.
3.2.5.4.3 Lubricating oil filters. Engines shall be designed to use full flow filter
elements conforming to type IV OF F-F-351 and MS35802. Full flow filter relief valves shall
be external of the filter case. The valves shall be designed to bypass oil when the pressure
drop is between 20 and 25 p.s.i. The valve closing pressure shall be not less than 20 p.s.i.
The filter inlet shall be internally baffled or so designed to prevent the oil flow from
impinging directly on the filter elements. The filter shall include a hand operated drain
valve which shall completely drain the filter for servicing.
3.2.5.4.4 Lubricating oil stainers. Strainers shall be the simplex metal edge type
With 0.005 inch spacing and enclosed manually operated cleaning device. The term "metal
edge" is defined as stacked metal discs or helically wound flat metal wire or metal ribbon
media. Wire cloth, screen, sintered metal or perforated plate media are not acceptable
under this specification. The strainer shall be sized to carry the full flow of 150 Saybolt
Seconds Universal (SSU) viscosity oil with a pressure drop of not more than 5 p.s.i. with
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