Technical  Bulletin

                Diesel Particulate Filter
     National  Clean  Diesel  Campaign

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.
Opacity testing with a smoke meter may also  be  useful
to confirm proper engine operation. Prior to  installing
a retrofit,  the exhaust system  integrity should also  be
Technology Selection

To select the best Diesel  Particulate Filter (DPF) 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-charger,  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

   Annual Miles Traveled (Highway) or Annual  Hours of
   Operation (Nonroad)

   Engine-out PM emission levels

   Engine duty cycle and the resultant exhaust temperatures.
           Diesel Particulate Filter (DPF)
            installed on municipal truck
   Any unique vehicle, equipment or engine operation that
   may create unusual conditions on the exhaust system or
   DPF. Conditions such as high vibration or shock loading
   may warrant special consideration in DPF selection and/or
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      (
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
Exhaust Temperature Data Logging

The exhaust temperature profile is one of the main factors
in determining whether a passive or active DPF system is
acceptable for a specific vehicle or piece of equipment. The
required minimum exhaust temperatures for regeneration
of passive DPF systems depend on the filter design and
often range from 210C for 40 percent of the time to 260C
for 30 percent of the time. Active DPF systems rely on an
additional heat source for filter regeneration. Therefore,
active  DPFs  are  not  as dependent as  passive DPFs
are on the engine duty cycle and the resultant exhaust
temperatures typically encountered in normal operation.
Exhaust temperature data logging must be  performed
on each vehicle. The filter manufacturer or an  authorized
representative must perform the data logging and analysis
of results. If varying vehicle routes or sporadic work loads
are used, or significant changes in ambient temperatures
are expected, data logging under a variety of conditions
may be necessary to accurately document the duty cycle
and  the resultant exhaust temperatures. Exhaust pipe
insulation may be used to retain heat. If insulation is used,
data logging should be performed with insulation installed.
When data  logging, temperature measurements must be
recorded at the installation location for the DPF. Fleets
should maintain data logging  records for all vehicles in
case they are needed for later reference.
                                                                                                 May 2010

Installation may be performed by the retrofit supplier, or the
retrofit supplier may provide training to fleet personnel to
perform installation.
In some applications, the DPF matches the dimensions of
the conventional muffler and can be installed as a muffler
replacement. In other cases the space available for DPF
installation on the vehicle or equipment is very restricted and
the DPF configuration must be custom-designed. Safety,
visibility, and vibration may also need to be addressed by a
custom installation. The  time required for DPF installation
will vary  depending on the situation and can range from
two to twelve hours or more for an active system. Special
equipment or a regeneration station may  be  necessary for
some active systems.
Since a DPF 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. To facilitate removal of the DPF for
cleaning, quick-release clamps are often used at the filter
Passive  DPF systems impose strict  requirements on
exhaust temperatures and must be mounted within a set
distance  from the exhaust manifold,  as specified by the
manufacturer. Exhaust pipe insulation  may be  used to
retain heat. Active systems  may have more flexibility in
their installation location.
Documentation should remain with the vehicle and/or in fleet
records which lists installation and vehicle information such
as mileage, opacity readings, date, device model number,
DPF serial number, installer, etc. Records should also be
maintained to  document when service is performed and
when the DPF is cleaned. If a fleet moves a DPF between
different vehicles, records should be carefully monitored to
identify if a particular vehicle or device appears to  require
different service intervals than another.
Backpressure Monitoring

An   exhaust  backpressure  monitoring   and  operator
notification system must be installed with every DPF. The
driver notification system  must be  installed where it is
readily visible by the driver during normal vehicle/equipment
operation. In some cases an additional notification system
may be  installed  in  the  engine compartment to  alert
maintenance technicians  of service  needs.  If exhaust
backpressure  exceeds  certain  thresholds, the operator
is  notified that maintenance is  needed.  It is important
that  all  vehicle/equipment operators and fleet service
technicians are properly trained to recognize and respond
to  backpressure warning signals  as well  as understand
whether or not the warning signal is continuously displayed
or only  during certain  operating conditions.  It is  also
important  that the backpressure  monitoring  system be
periodically inspected to confirm proper operation.