Two Products that don't make sense

[Tikvah]

Well, a lot more than two, but these two are on my mind:

At the truck stops: 

1.  DEF
Diesel Exhaust Fluid.
Really?  Exhaust fluid for a diesel? 

2.  Air Brake Fluid
Much like the DEF, it sounds fishy.
Air Brake Fluid is kind of an oxymoron. 
Where in an air system do they pour in fluid and why?

Both of these seem like blinker fluid or a muffler belt.  I've even seen Volkswagon radiators on sale. 
Are these things for real, or are they some kind of marketing ploy?

[bobofthenorth]

I assume the air brake fluid is some kind of alcohol to prevent frozen lines.  That's most certainly a real risk at this time of year where I live.  Read JC's recent thread if you doubt me.  In the case of DEF you can thank your very own EPA for that one.  I don't understand the chemistry but it is somehow involved in emissions control.  I believe the engine actually goes through a purge cycle which requires DEF to complete but I could be way off on that explanation.  I dunno from Chebbies but the current generation Powerstrokes require this crap to run.

[luvrbus]

We looked at a new Foretravel friends purchased the thing had a 15 gal DEF tank for the Cummins engine,air brake fluid is a antifreeze and rust inhibitor I don't think you can buy air brake fluid in CA because it causes reproduction problems in trucks and buses according to prop 65     

[Tikvah]

In cold climates, do we put Air Brake Fluid in our buses?  I saw the other thread, but I didn't understand everything.
Where do you pour in Air Brake Fluid?  Is there a reservoir someplace that I haven't seen?
Don't we have Air Dryers so that we don't get moisture in our air?  Then why the frozen lines? 

Sometimes I'm so ignorant of these things I wonder how I get away with owning a bus at all.

[luvrbus]

Air dryers only remove moisture coming from the compressor it has nothing to do with condensation caused by the elements.you still need to drain the tanks and keep the system in order 

[Tikvah]

Air dryers only remove moisture coming from the compressor it has nothing to do with condensation caused by the elements

I might debate that from a scientific standpoint (sometimes the practical application doesn't fit science)

If the air is DRY, you can't have condensation.  There isn't any moisture in the air to condense to the cold pipe walls.

[bobofthenorth]

In cold climates, do we put Air Brake Fluid in our buses?

If everything is working as it was designed "NO".  As you have already pointed out, with "dry" air there would be no condensation.  However "dry" is a moving target, depending on temperature.  If you are in conditions of rapidly changing temperature then the air in your system may not be "dry", despite having been "dry" earlier in the day.  Up here in the frozen north we can buy dryer cartridges that are alcohol impregnated.  The only time I ever had a freeze-up it was on a semi trailer.  On that occasion I poured a bit of gas line alcohol in the glad hands and hooked them up. 

[luvrbus]

That is the best I can do for you Dave   they didn't install drain valves on tanks for no reason just saying

[eagle19952]

Having spent to many years in the Arctic, I can asure you in the winter time, I ( or someone who worked for me) installed atleast one of these a week, often more....this would be where you put the air brake fluid...




http://www.class8truckparts.com/Haldex-Midland-Alcohol-Evaporator-A72420/dp/B002HUVXPW


in the "olden days" you'd put it here... in the even older "olden days" it would have had a glass mason jar...

[Jim Eh.]

Air brake antifreeze is basically methyl hydrate with some additives to make it not so harmful to you air system components. Usually a "mister" or "alcohol injector" is installed in your air system between your air dryer and your wet tank. This introduces alcohol or air brake antifreeze into your system to suspend any moisture and allow it to pass through your air system back to atmosphere. Well in theory anyway. Your air system takes in air from the atmosphere so wherever you are at, whatever the relative humidity, that is how much moisture you are introducing to your air system. thus the need for an air dryer and/or alcohol injector.

If wherever you are at you cannot find any air brake anti freeze or methyl hydrate you can also use gas line anti freeze or go to a drug store and get some Isopropyl Alcohol. The latter products should only be used in a pinch and not as regular practise. Truth be known Isopropyl Alcoho actually works better at suspending moisture in your car gas tank than gas line antifreeze.

DEF, hmmm. Urea. A patch or work around to help with the problems of tier 4 engines and their DPF or (diesel particulate filter). Fancy words for a simple catalytic converter. In my opinion the engineers in the 80s and 90s couldn't get it through their heads that the catalytic element of the exhaust had to be within 30" of the exhaust manifold to keep hot enough not to plug up so they continued to add on more and more complicated equipment (prone to more and more failures) to stop that from happening.

Catalytic elements are not anything new for a diesel engine. They have been used on mining equipment for a very long time. Scrubbers as they are sometimes called work fine without the injection and burning of diesel fuel to "self clean" if they are installed close enough to the engine to keep warm enough to not plug up. They do require some periodic servicing but don't require all the fancy addons of today's diesel engines.

FACT: an internal combustion engine produces bad things .... period. Putting lipstick on a pig is not really going to change the environment, just change the form. Now we not only have the same pollutants  that engines have always produced but now they have added other chemicals to the burn and puke cycle. All the while reducing the efficiency of today's engines.

I have not proven any of this in a labratory. I express this to be my views and outlook on life and hold offer no promises that if things were to be changed back to when trucks/buses were getting higher mileage that the air pollution would be reduced. Just my opinion.

Sorry if I rant on. I get pissed thinking of how many working people are getting screwed because of somebody's miserable attempt of making a change for the better without thinking things out.

[bevans6]

Diesel exhaust fluid.  Modern diesel engines are run lean to promote full burn of fuel and reduced soot production.  Running lean results in excess oxygen in the combustion and exhaust, which produces excessive nitrous oxide, which is a very harmful pollutant.  DEF is injected into the exhaust upstream of the catalytic converter, and allows the catalytic converter to break down the nitrous oxide to ammonia and Co2, both harmless elements.  So the lean burn reduces the soot, and the urea based DEF lets the cat. converter deal with the resulting NOX, and the result is a clean diesel engine.

Older diesel engines used things like exhaust gas recirculation to get the combustion process to not produce so much NOX, and the particulate filters to deal with the resulting soot, but they had other issues and didn't work well enough.  DEF is kind of the stage two of pollution control.  TomC will usually tell us that the modern engines are cleaner, more powerful, more economical, and need more computers than NASA needed to put men on the moon to even start.  Plus you need a degree in computer science and engineering to diagnose one.  Then you need the economic output of a small country to fix one.  Your position on pollution control is up to you, I'm personally more in favor of than not, but I'm happy to let other people buy the new trucks and I'll try to keep my old oil burners going for a while longer yet.

Brian

[Tikvah]

I appreciate all the helpful information.  I realize that the pollution technology debate will continue within many circles for years to come.

However it seems with our old DD engines the DEF is of no value and not something to touch. 
In addition, it seems that Air Brake Fluid is a nice idea, but no practical way to get it into my bus.  And as long as we stay away from serious cold and have an operational air dryer we shouldn't need it.

I guess that gives me some peace of mind.  Now I know where to check the oil I'm glad there isn't something else to check 

[TomC]

DEF is 32% Ammonia and deionized filtered water. It is non hazardous, but has to be stored in a plastic tank since ammonia reacts with aluminum. All heavy-duty engines use DEF. The main reactant is nitrous oxide. The smog devices on Diesel engines are exhaust gas recirculation (of which my 1984 Mercedes Turbo Diesel has-nothing new). EGR was as high as 30%, but is only about 10% now. That is all that is on the engine. All else is after treatment. Exhaust goes through a catalytic converter to heat and burn off excess contaminates then through the Diesel Particulate Filter that takes out the remaining soot. DEF is then injected into the exhaust stream at about a 3% rate to fuel used. That mixture then goes through the second stage called a Selective Catalyst Reduction. If you look at the scientific numbers of the chemicals used-We have nitrous oxide which NO2 (I believe) mixed with H20 (water) and Ammonia (NH3) that releases N (Nitrogen-of which 78% of our air is nitrogen) and H20 (water).
It is so effective-I went to one of my customers running DD13 around town for grocery store delivery. In 265,000mi, they had yet to go through a manual regeneration (when the DPF becomes stuffed up with soot and has to burn down to ash). The truck had a broken exhaust flex pipe that allowed me to rub my finger on the inside of the exhaust pipe. NO black soot at all-I could still see the gold color of the inside of the flex pipe. The systems are very effective. Because the smog devices are after the engine, the timing and tuning of the engines are now concentrating on fuel mileage and actually the engines run dirtier then before-but the aftertreatment takes care of the rest. We're seeing 80,000lb trucks getting 8mpg running no faster than 63mph. Good Luck, TomC

[Oonrahnjay]

... All the while reducing the efficiency of today's engines.
I have not proven any of this in a labratory. I express this to be my views and outlook on life and hold offer no promises that if things were to be changed back to when trucks/buses were getting higher mileage that the air pollution would be reduced. Just my opinion.
Sorry if I rant on. I get pissed thinking of how many working people are getting screwed because of somebody's miserable attempt of making a change for the better without thinking things out. 

     This kind of issue was my job for almost 30 years.  I couldn't have said it better. 

... However it seems with our old DD engines the DEF is of no value and not something to touch.  In addition, it seems that Air Brake Fluid is a nice idea, but no practical way to get it into my bus.  And as long as we stay away from serious cold and have an operational air dryer we shouldn't need it. 

      Yes, don't put any of the DEF in your bus (they have special, separate tanks anyway and a set of equipment to inject it into the engine so you couldn't use it, practically, even if you wanted to.)  If you're stuck with brake lines or valves frozen up and it's important/emergency to get going again, you could remove the fittings that attach the DOT tubing that lead out of the air dryer and (I guess, using a funnel) pour 2-3 ounces of brake de-icer into each line.  Depending on the setup of your bus, you might be able to get the de-icer into the tubing and leads to the first tank (if your first tank feeds all the others).  Another possibility would be to open the drains on your tanks and (using something like a turkey baster?) shoot 2-3 ounces into each tank; a lot of it would likely leak out doing it that way but you might get enough in to make a difference.
      Speaking of old-tech, DD 2-strokes are running straight-weight oil.  And they'd give you better fuel economy with old-style low-sulfur-diesel fuel - but ULSD has replaced it so you can't get the "better for us" fuel anymore.

[Oonrahnjay]

...   in the "olden days" you'd put it here... in the even older "olden days" it would have had a glass mason jar...

    An evaporator very much like that one (it was installed with the fluid container - no mason jar - pointing downwards) was on my bus when I got it.  There was no air dryer on my bus, so the fluid (or vapor,) was drawn directly into the compressor.