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What is Hartridge Smoke Unit (HSU) ? for Diesel engine emission

  1. Feb 24, 2009 #1
    I am working of the Diesel Emission Project, however i have some problem in evaluating the filtraion power of the Particulate Remover Unit. The following is my question:

    What is Hartridge Smoke Unit (HSU) ?

    Could any one can provide some picture of different level of HSU so that I can understand the visual senario of different value (e.g. 25, 50, 100, 150)?

    Thank you very much for your kind help.
  2. jcsd
  3. Feb 24, 2009 #2


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    Pictures won't give you a good idea of smoke opacity, which is what you're interested in. A value of 0 indicates perfect transmission, or zero opacity. A value of 100 indicates total absorption, or complete opacity. This is referenced (in the case of HSU) to a transmission length of 430mm, at 100°C and atmospheric pressure. Values in between are not linear with respect to actual light absorption.
  4. Feb 25, 2009 #3
    Thank you very much for your reply.
    However, I would like to ask how to verify the meaning that the emission is clean or smoky in terms of HSU?
    Could you provide some picture??

    Thank you very much for your help.
  5. Feb 25, 2009 #4


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    0 is invisible, 100 is a thick, dense smoke. Then you have everything else in between. As I stated, pictures are pretty useless, since this isn't a subjective measure, and the same smoke level can look good/bad depending on light conditions, background colour, and dilution.

    Pretty smoky:

    Pretty clean:
  6. Feb 17, 2010 #5
    Anyone who can tell me the corelation between Hartridge Smoke Unit (HSU) and FILTER SMOKE NUMBER(FSN) as I have the two systems giving one in HSU and the other in FSN.I would like to compare the result given by the two SYSTEM
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