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Old 11-17-2012, 10:33 AM
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floydarogers floydarogers is offline
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Originally Posted by Flyingman View Post
Supposedly DEF is metered to inject at some % (1-3%) based on fuel flow measured. This makes sense as it is just a chemical reaction, so many parts per million of DEF to each part of fuel. 1% would be 10,000ppm of DEF?
No. The ST810 and Intro to diesel tech docs that have been posted here make it clear that they use an active NOx sensor to drive the amount. Remember, there are actually two catalysts: the one in the DPF (which reduces NO--> NO2), and the SCR (which completes the reduction to NOx --> N2 + O2)
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