G424 Service Manual LPG Fuel System(Low Emission Version)95
Catalytic Muffler
The catalytic muffler is mounted in the exhaust gas
stream of G430 engine. The catalytic muffler facilitates
oxidation and reduction reactions that reduce the
amount of unwanted constituents in the exhaust gas
stream. Catalytic mufflers have sound deadening and
spark arresting features incorporated into the design.
After combustion the contents of the engine
cylinder(s) are expelled into the exhaust system.
These hot gases next travel to the catalytic muffler.
The catalytic muffler is made up of a shell (1)
incorporating an inlet (2) and an outlet (4). Inside, the
catalytic muffler contains a three-way catalyst section
(3) as well as sound dampening and spark arresting
features. The three-way catalyst section (3) consists of
a honeycomb coated with a mixture of platinum,
palladium and rhodium. The hot exhaust gases enter
the catalytic muffler through the inlet (1). Next the hot
exhaust gases flow through the catalyst section (3)
where an oxidation and reduction reactions take
place. These chemical reactions reduce the amount of
CO, HC and NOx in the engine exhaust. The exhaust
gas then flows through the outlet (4).
1
4
3
2
Reaction Stage
CO + O
2
= CO
2
Oxidation
HC + O
2
= H
2
O + CO
2
Oxidation
NO
X
+ CO = N
2
+ CO
2
Reduction
NO
X
+ H
2
= N
2
+ H
2
O Reduction
NO
X
+ HC = N
2
+ H
2
O = CO
2
Reduction
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