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Question in U.S. Diesel Emission Standards

  1. Jun 28, 2009 #1
    I wonder is what are the legal and application area difference between "Tier","EPA" and "California" Emission Standard in U.S (I am not asking the allowable emission levels).

    Also, Is there any difference in on-road and off-road standads(again, I am not asking the emission levels)?

    Thanks for your kind help in advence.
  2. jcsd
  3. Jun 29, 2009 #2


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    Gold Member

    The EPA set emissions levels by "Tier" (e.g. "this Tier 4 level the EPA have set is a right bastard!"). The two are synonymous. Don't know about CARB, I'll do some reading at work and let you know later in the week.

    On and off-road standards (for EPA and EU) are broadly the same in terms of allowable pollutant concentrations, but do differ in introduction dates, and (depending on application) the way the figures are calculated. That is to say, we (industrial) are currently developing to meet Tier 4 emissions levels but the automotive guys did this a while back.
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