Perkins M65, Руководство по установке, Страница: 21 / 54

TPD 1399E Chapter 5
Page 15
Engine Cooling Systems
Sea Water Systems
A completely separate sea water system should be
provided for each engine to prevent a blockage
resulting in the need to shut down more than one
engine. A typical system is shown on (A).
The water intake fitting (A1) should not project
appreciably below the bottom of the hull and it should
be situated well clear of other components such as
shafts, logs, rudders to prevent flow problems at high
speeds. If desired the rear edge of the water intake
may be allowed to project more than the front, by no
more than 6mm, to give a slight scoop effect, but if
this is done it is necessary to locate the fitting so that
it cannot be inadvertently partially rotated.
The intake fittings and pipework should have a
minimum bore of 25mm. Inboard of the intake fitting
a sea cock must be provided (A2). This should be of
the full flow type giving unobstructed passage to the
water in the open position, with a minimum bore of
25mm.
Between the intake fitting and the sea water pump
on the engine, there should be a strainer (A3) which
should be easily accessible for routine examination,
and the lid should be easily removable. Where
possible mount the strainer so that the top is just
above the waterline - this will allow the strainer to be
cleaned without closing the sea cock.
From the sea water strainer a pipe should be run to
the sea water pump inlet connection on the engine (
B1). The pipe may either be mainly rigid, of for example
copper or cupro-nickel, or flexible, but only flexible
hose which is reinforced to prevent collapse should
be used. Rubber hose connections in the sea water
system should be kept as short as possible and should
be reinforced with a minimum of three layers of
canvas. The system must be sufficiently flexible to
permit the engine to move on its anti-vibration
mountings. The sea water pump connection is for
hose with a 32mm bore.
A small supply of seawater is often needed to cool
and lubricate the shaft log. A connection point (B2) is
provided to suit 10mm bore hose.
Care should be taken to use compatible materials
in the sea water systems, to prevent excessive
electrolytic corrosion. Systems incorporating copper,
cupro-nickel, stainless steel Type 316, gun-metal,
silver solder, and aluminium brass will generally be
satisfactory. Components made from lead, iron, steel,
aluminium or its alloys, zinc or magnesium, should be
generally avoided.