Technical Bulletin
Diesel Oxidation Catalyst National Clean Diesel Campaign
Installation, Operation, and Maintenance www.epa.gov/cieandiesei
Pre-lnstallation
Prior to installing any retrofit device, it is important
to perform a thorough engine inspection and review
maintenance records to ensure proper engine operation.
Vehicles with excessive fuel or lubrication oil consumption
should be repaired prior to installing retrofit technologies.
Excessive blowby emissions can be a sign of engine wear
and further inspection of the engine may be necessary.
Prior to installing a retrofit, the exhaust system integrity
should also be confirmed.
Technology Selection
To select the best Diesel Oxidation Catalyst (DOC) for a
specific vehicle, it is necessary to identify:
• Vehicle Type: Highway or Nonroad
• Vehicle Class: School Bus, Class 8ATractor, Ferry,
Locomotive, Forklift, etc
• Vehicle Specifications: Manufacturer, Model, Model Year
• Engine Specifications: Manufacturer, Model, Model Year,
Displacement, Horsepower, Engine Location on Vehicle,
Turbo-charge, Exhaust Gas Recirculation (EGR)
• EPA Engine Family Name: Can be found on the engine's
emission label and contains 12 or 13 characters such as
TCP7.2RZBDBRB or 3NVXHO466ANA
Diesel Oxidation Catalyst (DOC)
on Track Dozer
Annual Miles Traveled (Highway) or Annual Hours of
Operation (Nonroad)
Engine-out PM emission levels
Any unique vehicle, equipment or engine operation that
may create unusual conditions on the exhaust system or
DOC. Conditions such as high vibration or shock loading
may warrant special consideration in DOC selection and/or
mounting.
The United States Environmental Protection Agency (EPA)
and the California Air Resources Board (GARB) maintain
lists of verified diesel retrofit technologies that define the
specific applications and engine operating criteria that
must be met to successfully apply a particular retrofit
technology (www.epa.gov/otaq/retrofit/verif-list.htm).
When installed as described on the verified technologies
list and within the verified scope of coverage, a device
is expected to achieve the verified performance and
durability.
Exhaust Temperature Data Logging
To achieve verified levels of emissions reductions DOCs
typically require a minimum exhaust gas temperature of
150°C. This temperature requirement is met in normal
operation with most duty cycles. Data logging is not
typically necessary to evaluate acceptable exhaust gas
temperatures prior to DOC installation.
Installation
Installation may be performed by the retrofit supplier, or
the retrofit supplier may provide training to fleet personnel
to perform installation.
In most applications, the DOC may be configured to
match the dimensions of the conventional muffler and
can be installed as a muffler replacement. In other cases
the space available for DOC installation on the vehicle or
equipment is very restricted and the DOC configuration
must be custom-designed. Safety, visibility, and vibration
issues may also need to be addressed by a custom
EPA-420-F-10-030
May 2010
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installation. The time required for DOC installation will vary
depending on the situation and is generally one to three
hours.
Since a DOC typically weighs more and may be larger than
the muffler, stronger clamps and brackets are required in
place of those used with the original muffler. Failure to utilize
appropriate hardware and follow mounting instructions can
result in a failure of support brackets and damage to the
equipment or vehicle.
The DOC must be mounted within a set distance of the
exhaust manifold, as specified by the manufacturer. While
not normally necessary, exhaust pipe insulation may
be used to retain heat when the DOC is mounted a long
distance from the turbo charger.
Documentation should remain with the vehicle and/or in
fleet records which lists installation and vehicle information
such as mileage, date, device model number, installer, etc.
Operation and Maintenance
Once properly installed, DOCs require little maintenance.
DOC manufacturers and product suppliers should provide
vehicle service technicians with training on proper
retrofit maintenance procedures. Periodic inspection and
tightening of mounting hardware is typically appropriate.
Plugging is very rare, but it can occur in older, high-emitting
or poorly maintained vehicles and/or if an engine has a
mechanical failure. Long duration idling should also be
avoided. If a DOC is overwhelmed with unburned fuel
or lubricants (ash) it may need to be cleaned and the
manufacturer's instructions should be followed.
It is important to properly maintain vehicles and monitor
fuel and lubrication oil consumption. A bad fuel injector or
increased oil consumption may be masked by a DOC. The
DOC may be damaged by excessive fuel or oil consumption
or a poorly maintained engine.
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