Northern Lights IM1000 Installation Manual - page 15
IM1000 02/13
Extreme care is required in the design and installation
of fuel systems. Fuel leakage presents a fi re and explosion
hazard. Follow U.S.C.G. codes and use only components
that are specifi ed for marine applications.
Each Northern Lights generator has a fuel manifold
with connections for supply and returned fuel. The lines
should be no smaller than these pipe sizes. Pipe sizes can
be found on the installation drawing.
Fuel lines must have as few connections as possible.
The line should be routed where they are protected from
damage and vibration. They should be clamped securely
about every 15" (58 cm). Metal fuel lines should be
bonded to the common bonding conductor. Fuel lines
must be kept away from hot engine or exhaust areas.
Fuel should be drawn from the top of the tank and
run at tank level as close to the engine as possible. If a
line breaks, this will reduce the danger of fuel siphoning.
The fuel pick-up tube should not draw fuel directly from
the bottom of the tank but should be located 1 to 2 inches
from the bottom and cut off diagonally. The tank must be
suitably vented. Metal tanks must be properly bonded.
The bonding strap should be connected from the fuel fi ll
to the fuel tank if a rubber connection is used. A water
separator type fi lter should be used between the tank and
the generator set and located as close to the generator as
possible.
To comply with U.S.C.G. regulations for boats for
hire, a shut-off valve must be installed at the tank
connection to stop fuel fl ow. An electric or manual valve
can be used. Electric valves should be energized only
when the engine control switch is in the run position.
Valves must have a manual override. If a manual valve is
used, provisions must be made to operate it from outside
the compartment where the tanks are located, preferably
from above the deck.
If the engine and fuel tank are separated by more than
12 feet (3.7 m), a Coast Guard approved shutoff valve
must be installed at the engine. This valve makes it easy
to change the fi lters without draining the entire fuel line
and allows for easier engine servicing. If the fuel tank is
located above the engine, provision should be made to
shut off the fuel when the engine is not running and for
servicing of the fi lters.
If the fuel tank is located below the engine, there is a
maximum lift of 39 inches (1 m) on the suction side of the
lift pump. Long runs of piping with multiple
connections and vertical looping create many points at
which air can be trapped or sucked into the system. Air
can hamper engine performance and create starting
problems. The fuel lines should not be teed into the fuel
lines of any other engine. The supply pump on the
generator does not have the power nor the capacity to
overcome the draw of the propulsion engines.
When lines are teed or joined at a common manifold,
air will be drawn into the fuel system if there is a leak at
any point, including at the propulsion engine. Air will be
drawn into the fuel system, which causes low power, hard
starting or generator engine shut down.
Due to the high return fuel rate of many propulsion
engines, it is common for air problems to show up in the
generator before it shows up in the propulsion engine.
Every effort must be made to prevent air from being
drawn into the system at any point.
If a lift of more than 39 inches (1 m) is required, a
pump and fl oat tank arrangement can be employed.
The pump should be energized only when the generator
control switch is in the run position.
Besides providing adequate air for engine
combustion, the generator end requires cooling
ventilation. The ventilation requirements for each
generator set is available from Northern Lights.
Normally, the generator set is located in the same
compartment as the main engine. Because the
generator is usually small in relation to the main engine,
the ventilation is adequate. If the generator set is located
in a separate compartment, it is important that adequate
ventilation is provided while the vessel is both underway
and not moving.
Vents must be located so moisture is not ducted into
the generators. The vents should be protected so that
water is not drawn into the generator during washdown.
Make sure that no moisture or contamination from
the bilge can be drawn up into the generator itself.
Ventilation
Fuel System
13