Northern Lights IM1000 Installation Manual - page 13
IM1000 02/13
Failing to follow these instructions when installing
a certifi ed engine in a vessel violates federal law (40
CFR 1068.105(b)), subject to fi nes or other penalties as
described in the Clean Air Act.
If the exhaust manifold is signifi cantly below the
water line, causing a rise of greater than 4 feet (1.23 m),
an insulated dry stack arrangement can be used to raise
the waterlift muffl er above the exhaust manifold (
see
Figure 4
). The uncooled portion of the exhaust piping
must be insulated.
The distance from the top of the loop to the thru-hull
fi tting should be a drop of 12" (30 cm) minimum, sloping
at least one-half inch per foot (42 mm/m) of distance. This
will prevent backfl ow of water into the exhaust manifold
due to pitching of the vessel. Remember, four feet is the
maximum allowable vertical lift between the muffl er and
the top of the exhaust loop. Pipe hangers should be used
to support the tubing and prevent dips or pockets which
allow water to build up in low sections of the line. This
causes back pressure and increases the noise level.
High exhaust temperature shutdown or alarm
switches are available options and are required on wet
exhaust systems used with keel cooled engines.
WARNING: Scoop type water inlet fi ttings must
not be used. They allow water to push up past
the raw water pump when the generator is not
in operation while cruising, and this allows water
to fi ll up the muffl er. With no exhaust pressure
to force the water out of the muffl er, the water
backs up into the exhaust manifold and into the
cylinders.
WARNING: If the engine is cranked for a consid-
erable period of time without fi ring, raw water can
fi ll up the muffl er and back up into the exhaust
manifolds due to lack of exhaust pressure to
evacuate the muffl er.
If the engine must be cranked for more than
one minute at a time without starting (for example,
to bleed the fuel system), close the seacock and
remove the raw water pump impeller until the
engine can be started. Then stop the engine
immediately, replace the impeller and open the
seacock.
The exhaust water piping should be isolated and not
connected to the exhaust piping of any other engine.
The installed exhaust system should not create exhaust
back pressure greater than 30" (760 mm) of water
for a turbocharged engine and 48" (1200 mm) for a
non-turbocharged unit, measured at the engine exhaust
elbow. The exhaust outlet must be located as close to the
outboard side of the transom to minimize exhaust gases
being drawn onboard the vessel. The exhaust outlet
should not be located near hatches or portholes and must
be above the water line.
DRY EXHAUST
Because of the high temperatures involved in a dry
exhaust system, each part of the system must be well
insulated from any combustible surface and equipped
with guards to prevent burns.
Dry exhaust shall not come in direct contact with
bulkheads or other combustible materials. A clearance of
9" (23 cm) must be maintained between the exhaust and
any combustible material, unless protected by suitable
insulation.
The insulating material must be suitable for the
temperatures involved, and thick enough to prevent the
surface of the insulation from reaching a temperature
above 71° C (160° F). The exhaust system must be piped
so that air circulates freely around it.
Water must be prevented from entering the engine
through the exhaust. Provision must be made for
drawing off rain water entering the silencer, or putting a
tee connection in the exhaust pipe.
The exhaust pipe between the manifold and the
silencer should be water jacketed but may be dry if
adequately shielded or covered to prevent burns.
A fl exible connection must be used between the engine
and the exhaust piping. Exhaust piping, silencers and
other parts of the system must be supported through
the length of the system. It is important that the engine
exhaust elbow does not support any weight of the
exhaust system.
Emission-Related Installation & Instructions
11
revised 2-25-13