Emissions Durability Period and Air Index
Information On Your Engine Emissions Label
Engines that are certified to meet the California Air
Resources Board (CARB) Tier 2 Emission Standards must
display information regarding the Emissions Durability Period
and Air Index. The engine manufacturer makes this
information available to the consumer on emission labels.
The Emissions Durability Period describes the number of
hours of actual running time for which the engine is certified
to be emissions compliant, assuming proper maintenance in
accordance with the Operating & Maintenance Instructions.
The following categories are used:
Moderate: Engine is certified to be emission compliant for
125 hours of actual engine running time.
Intermediate: Engine is certified to be emission compliant
for 250 hours of actual engine running time.
Extended: Engine is certified to be emission compliant for
500 hours of actual engine running time.
For example, a typical walk-behind lawn mower is used
20 to 25 hours per year. Therefore, the Emissions
Durability Period of an engine with an intermediate rating
would equate to 10 to 12 years.
The Air Index is a calculated number describing the relative
level of emissions for a specific engine family. The lower the
Air Index, the cleaner the engine. This information is
displayed in graphical form on the emissions label.
Emissions Compliance Period On Engine
Emissions Compliance Label
After July 1, 2000 certain Sears engines will be certified to
meet the United States Environmental Protection Agency
(USEPA) Phase 2 emission standards. For phase 2 certified
engines, the Emissions Compliance Period referred to on
the Emissions Compliance label indicates the number of
operating hours for which the engine has been shown to
meet Federal emission requirements. For engines less than
225 cc displacement, Category C = 125 hours, B = 250
hours and A = 500 hours. For engines of 225 cc or more,
Category C = 250 hours, B = 500 hours and A = 1000 hours.
This engine has a moderate rating with and Air Index of 3.
The EPA Emissions compliance period is Category C. The
diplacement of this engine is 190 cc.
Below is a generic representation of the emission label
typically found on a certified engine.
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