Loss Of Activity In The Catalytic Converter - Kohler SFGLD480 Operation & Maintenance Manual

6. LOSS OF ACTIVITY IN THE CATALYTIC CONVERTER

The activity of a catalytic converter drops progressively over time, although a series of mechanisms can cause
said activity to be lost before the end of its useful life, significantly reducing exhaust pollutant reduction efficiency
as shown on the following table:
Mechanism Description
CHEMICAL Poisons are those elements or compounds which are present in engine exhaust gases and
POISONING combine chemically with the materials of the catalytic converter, causing them to lose activity. In
most cases when poisoning occurs the damage is irreversible.
Inhibitors are those elements that, when present in engine exhaust gases, can make the catalytic
converter lose efficiency in certain operating conditions. However, the catalytic converter recovers
CATALYTIC its normal performance when the inhibitor is not present in the exhaust gases or when operating
INHIBITION conditions change. One example of this is sulphur, which does not allow the catalytic converter to
operate correctly at low temperatures, and acts as a poison. When the system starts operating at
high temperatures it is eliminated and normal efficiency levels are regained.
The loss of activity by a catalytic converter through dirtying or masking happens when an inert
residue or ash from the exhaust gases is deposited on the catalytic surface, blocking it and
DIRTYING OR
preventing it from working correctly. In many cases, the residue can be eliminated from the
MASKING
catalytic surface using cleaning methods that allow it to regain normal catalytic converter activity
levels.
Thermal deactivation of the catalytic converter happens when the creep temperature of the
materials that make it up is exceeded. This type of problem can happen as a result of a sudden
THERMAL
increase in the pollutants to be eliminated which, when they are converted through exothermic
DEACTIVATION
reactions, cause the thermal limits of the materials of the catalytic converter to be exceeded,
causing irreversible damage to its structure.
The erosion of the materials making up the catalytic converter substrate is due to natural causes
MECHANICAL (time) or to wear caused by an excessive presence of solid materials in the exhaust gas.
EROSION AND Mechanical deactivation means that the internal channels of the catalytic converter become
DEACTIVATION blocked or their walls collapse due to mechanical problems (excessive vibration, blows, excessive
erosion, etc.). This type of damage to the catalytic converter is irreversible.
PRODUCT INFORMATION
IC-C-D-40-003e
OXIDATIVE CATALYTIC CONVERTERS
Table 5. Causes of loss of activity in the catalytic converter.
INDEX
A
2.7.6
DATE
Dep. 2
May 2012
O&M_2.002211.810_A_10_2016
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