DEF?

Discussion in 'Questions From New Drivers' started by bobbybaldwin, Nov 12, 2013.

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  1. PackRatTDI

    PackRatTDI Licensed to Ill

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    The Volvo DPF/SCR system seems to have the right idea. Its designed to not run active regenerations under normal operating conditions.
     
    PackRatTDI, Nov 12, 2013
    #11
  2. GITRDUN45

    GITRDUN45 Heavy Load Member

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    You own one? What year? Average MPG Bestto worst? Thanks
     
    GITRDUN45, Nov 12, 2013
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  3. Lepton1

    Lepton1 Road Train Member

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    The more you idle the more you will need to regen? If so that might explain why I haven't had to regen my Cascadia in 5 months, I hardly idle.
     
    Lepton1, Nov 12, 2013
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  4. Shadow Captain

    Shadow Captain Light Load Member

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    SAY WHAT?? The DEF system has nothing to do with the Diesel Particulate Filter or the regen system! The exhaust fluid is called a SCR strictly added to reduce oxides of nitrogen also known as NOx.
     
    Shadow Captain, Nov 12, 2013
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  5. PackRatTDI

    PackRatTDI Licensed to Ill

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    Company truck. 2011 Volvo 780 sleeper. Averaging 6.6 right now thanks to lugging heavy wagons. Best was averaging nearly 10mpg bobtailing from El Paso, TX to Jefferson City, MO. Worst I'd say was 5.9.
     
    PackRatTDI, Nov 12, 2013
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    GITRDUN45 and blairandgretchen Thank this.
  6. PackRatTDI

    PackRatTDI Licensed to Ill

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    Here's what is going on when your truck uses DEF:

    "Selective catalytic reduction is used to reduce the amount of NOx#released into the atmosphere. Diesel exhaust fluid (from a separate DEF tank) is injected into the exhaust pipeline, the aqueous urea vaporizes and decomposes to form#ammonia#and carbon dioxide. Within the SCR#catalyst, the NOx#are catalytically reduced by the ammonia (NH3) into water#(H2O) and#nitrogen#(N2), which are both harmless; and these are then released through the exhaust."

    Volvo takes it one step further and uses the NOx to oxidize the soot passively in the diesel particulate filter which occurs at a lower temperature than is needed with a conventional active regeneration system. Volvo figured if they were going to be tackling the NOx downstream of the DPF with the SCR, they might as well tweak the engine to reduce soot, which increases NOx and then use that NOx to clean the DPF instead of running active regens.
     
    PackRatTDI, Nov 13, 2013
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    blairandgretchen, GITRDUN45, Lepton1 and 1 other person Thank this.
  7. blairandgretchen

    blairandgretchen Road Train Member

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    That takes care of THAT!
     
    blairandgretchen, Nov 13, 2013
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  8. white wolf

    white wolf Light Load Member

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    yah if ya run out just piss in the tank
     
    white wolf, Nov 13, 2013
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  9. ironpony

    ironpony Road Train Member

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    Yep... that'll really work well. NOT!!!
     
    ironpony, Nov 13, 2013
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  10. Grumppy

    Grumppy Trucker Forum STAFF Staff Member

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    I cant understand why or how someone could run out of DEF. I drive an 07 Frieghtliner & recently while it was in a Ryder shop for a couple of weeks, I drove a '12 or '13 model which was my first experience with DEF. It had 4 little green "dash" marks for the DEF level. I kept waiting for it to move but never would. Finally after about 2/12 tanks of diesel, one light finally went out. I dont remember exactly but I drove that thing for over a week & probably 6 or 7 tanks of diesel before I ever put 11 gallons of DEF in it... I though WTH? Is the gauge broke? But, I found out it just doesnt use very much. So, now I know.

    Which leads me to my original statement... I cant understand why or how someone could run out of DEF...???
     
    Grumppy, Nov 13, 2013
    #20
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