Perkins M190C, Руководство по установке

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N40475 Chapter 4
Page 9
Exhaust systems
A range of exhaust components are available for use
with all types of exhaust system. The components
are designed to connect together, allowing complex
systems to be built from stock items, to suit most
installations.
Caution: In all types of exhaust system the exhaust
back pressure must not exceed 15kPa, when
measured within 305mm (12 inches) of the exhaust
outlet from the engine.
Wet systems
Wet exhaust systems, where the auxiliary water
used to circulate through the heat exchangers on the
engine is finally dumped into the exhaust pipe to cool
the exhaust gases, are the most common choice for
small craft. Their principal advantage is that a rubber
exhaust hose may be used, with a fairly low surface
temperature, which presents no risk of fire.
The exhaust bore is 125mm (5”).
A general arrangement for such a system is shown on
Figure 1. In many cases the exhaust outlet passes
through the transom, just above the waterline (1). It
will be seen that a minimum fall of 5
O (2) is required,
and that the point of water injection must be at least
8 inches above the waterline (3), although the actual
height necessary for a particular boat can only be
decided in the light of the exhaust system design,
and the pitch and roll which may be encountered in
service.
Caution: It is essential that the exhaust system is
designed so that water from the exhaust does not
enter the engine under any conceivable operational
condition.
Figure 1