Cooling - Fresh Water System, Heat Exchanger - Beta Marine Beta 10 Operator's Maintenance Manual

HEAT EXCHANGER COOLING
Sea Water Level
All diesel engines require a cooling system. Generally all
modern seagoing boats with wooden or GRP (Glass
Reinforced Polyester) hulls normally have a Heat
Exchanger 'Fresh Water' cooling system.
Heat Exchanger cooling takes in sea water through the
bottom of the hull via a seacock usually with a strainer, to
the seawater pump mounted on the engine. The seawater
is pumped through piping to the heat exchanger where it
passes through the cupronickel 'tubestack'; first though
the bottom pipes, then back through the top pipes and
then out into the exhaust injection bend. From the
ENGINE 'FRESH WATER' COOLANT
It is essential that a solution of fresh water and anti-freeze
is used as engine coolant. The coolant solution must be a
mixture of fresh water and anti-freeze (Ethylene Glycol
based conforming to BS6580:1992) with the antifreeze
being a 50% solution (this also applies to warm and
tropical climates). This not only stops 'freezing up' in
winter, but it also prevents overheating and corrosion. The
ratio of anti-freeze to 'Fresh water' must be 50%. The
RAW WATER COOLING - KEEL COOLING
Older marine engine designs have used 'Raw Water'
cooling. This is when the seawater circulates directly
through the engine cooling circuit and will over time
corrode the inside of the engine. Seawater is very
corrosive and the salts can also cause scale build-up in
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injection bend the seawater falls into the waterlock and is
then blown with the exhaust through a 'gooseneck' and
out of the stern of the boat. The engine cooling has a
closed circuit that uses a coolant solution of 50% 'Fresh
Water' and 50% antifreeze. This coolant circulates round
the engine collecting heat and transfers the heat to the
seawater in the heat exchanger as it circulates around the
outside of the cupronickel 'tubestack' pipes.
A typical heat exchanger cooling system is shown on the
inside front cover, and detail drawings are included in the
following pages to ensure a reliable installation.
warranty is invalid if the correct percentage / ratio is not
used. The anti-freeze in the fresh water system enables
the boiling point of water to rise to 124°C with a 13 psi
pressure cap fitted. The water temperature alarm switch
will however be activated at 95°C to 100°C. If no anti-
freeze or a very weak solution is used, then the water
temperature switch may not be activated before coolant is
lost.
narrow coolant passageways. Beta Marine do not offer
'Raw Water' cooling.
Inland waterways 'Narrowboats' with 8mm steel side
walls are ideal for Keel Cooling.
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