Emissions test opacity results and comparing with older and newer diesels ?

[verk]

Hi TDR forum. Had my biennial emission test today and the result was 2.4 (unit ? is this just a percentage ? ) for opacity with an allowable limit of 20 (state of CT). I then thought to look at history and it's been pretty consistent ranging from 0.9 to 3.1. Does this figure represent anything meaningful to anybody in terms of particulate emissions ? Would like to see other results like Class 8 trucks as well as newer diesel with DPF. Anybody have any resources or figures for comparison ?

Sven

 

[Bob4x4]

That number is pretty good.Years ago at a seminar I put on I tested a very lightly modified first gen at 30% and my 94 with a Cummins 230/600 update kit at 5%

 

[Wayne M.]

I am a New York State HD inspector, and I run a lot of opacity tests. The fleet ranges from brand new (1year old) F super duty, HD GHG 17 (newest emission) class 8 trucks all the way back to a old smoky Mack RD with a mechanical Cat 3406.
You would expect near zero from a current truck with a clean stack up to high teens-20’s for a older pre emission truck that’s running well.
The opacity meter is calibrated daily with a tinted filter that’s put in the meter lightpath. The unit is percent of opacity.