Exhaust
System
GENERAL
The exhaust system must efficiently expel all engine
combustion products and muffle exhaust noises with
minimum back pressure. If back pressure is too high,
the volumetric efficiency of the engine is reduced,
fuel economy drops, exhaust temperature increases,
and valve life is shortened.
Back pressure must not exceed 27 inches
(686
mm)
of water column for the rated load when measured
with a manometer at the exhaust manifold, Figure
3.
.Ill
.....
INCHES
OF
WATER
INCHES
OF
MERCURY
OUNCES
FIGURE
3.
BACK PRESSURE TEST WITH MANOMETER
Inhalation
of
exhaust gases might
result in serious personal injury
or
death. Inspect exhaust system audibly and visually
for leaks daily. Repair any leaks immediately.
INSTALLATION
TIPS
Points to remember when installing an exhaust
system are:
Exhaust pipes should be as short as possible with
a minimum of fittings.
The muffler must be as close to the engine as
possible. Mufflers which are too far from the
manifold remain cool and collect carbon residue.
Pitch exhaust pipe upward from exhaust outlets
to avoid entrapment of raw diesel fumes in muffler
at shutdown.
Avoid sharp bends by using large radius elbow.
Check back pressure with a mercury or water
column type manometer.
Position the exhaust outlet away from the engine
air intake.
Exhaust noise can be suppressed or reduced by:
Using a heavy duty exhaust system with a more
efficient muffler.
Installing a deflector at the exhaust outlet to
direct exhaust toward the ground, but away from
the operator.
Using a resonator in addition to a muffler.
,
Avoiding use of flexible lines.
The importance of exhaust systems (normally
supplied by the customer) cannot be over-
emphasized.
A
poor or clogged system causes low
Exhaust
Smoke
A
light gray or light blue smoke may be a result of low
power, overheating and engine damage.
A
poor
ambient temperature and light load. This smoke is
exhaust system increases back pressure which
unburned fuel (not harmful to the engine) and disap-
reduces efficiency.
pears when more load is applied.
Black smoke indicates overfueling (more fuel than
oxygen) and is usually caused by overloading. The
smoke or unburned fuel becomes carbon when
raised to a high temperature. Carbon contributes to
engine damage because
it
contaminates the lubricat-
ing oil.
Inhalation
of
exhaust gases might
LiIl
result In serlous personal Injury or
death.
Do
not use exhaust heat to warm a room,
compartment, or storage area.
Vent exhaust gases outside. Use flexible tubing only
between the engine exhaust outlet and rigid piping.
WARNING
If the manufacturer tailors his own
exhaust system, an Onan applica-
tions engineer must approve the installation for war-
ranty purposes.
INDOOR INSTALLATIONS
Locate exhaust outlet far from air inlet to avoid
recirculation. The engine exhaust is tapped for 1-1/2
inch thread. Use flexible tubing to connect theengine
exhaust to rigid pipe or muffler. Shield the line if
it
passes through a combustible wall (Figure
4).
lfturns
are necessary, use sweeping (large radius) elbows. If
pitched upward, install acondensation trap at point of
rise, Figure
5.
14
Redistribution or publication of this document,
by any means, is strictly prohibited.
To Next Page
Loading...
Need help?
General
