I believe that microdroplets are potentially more damaging from cavitation than solutions. Both will cavitate under similar conditions though. There's lots of other variables involved.

I agree with Johno (FWIW). What is starting to fry your brain is well known to colloid/surface chemists. The answer/solution (pun intended) lies in surfactant application.

quote:

Originally posted by EuDeMan:
can anyone clear up the suspension v. solution question?
someone pls clear this up, my brain is going to overheat

I just got off the phone with the Bosch Factory Training Instructor. Although he was the one who provided the confirmation about cavitation in IPs, he was not aware of cavitation being "the most common damage to IPS". Fuel quality, especially water and dirt contamination, is the most common cause of injector pump damage, not cavitation. He went on to say that cavitation is NOT A FUEL CONTAMINATION PROBLEM, in his understanding. In fact he did not know if water had any effect on cavitation. Cavitation is a problem found in certain injection systems, using normal diesel fuel.
OK, to recap:
1) Cavitation is a real phenomenon that damages Injection systems.
2) Cavitation is not dependant on contamination by water to occur. Water may or may not make cavitation worse. (I suspect it does, but don't have proof)
3) Cavitation damage shows up on high-mileage engines
4) Fuel Quality is the major cause of Injection system damage. Specifically water and dirt.

The 3rd Edition of Bosch Diesel Engine Management discusses cavitation damage to injector pumps.

quote:

Fuel quality, especially water and dirt contamination, is the most common cause of injector pump damage, not cavitation.

The above makes absolutely no sense to me.

In IPs the possability of gas cavitaion is very low since they are designed to work with diesel fuel. The pressure at which diesel fuel can cavitate without contamination present is near zero since the pumps are designed to avoid creating conditions where uncontaminated diesel fuel is flowing through the IP.

However..since water is NOT supposed to be present in diesel fuel steam cavitation cannot be "designed out" of IPS.

I suppose I should just be happy when it is acknowledged that water contamination should be avoided to lengthen IP life.

Hey..Wait!

I AM!

If you talk to him again, ask him if he is a proponet of fuel additives to disperse water or demulsify it?

quote:

Originally posted by johno:
4) Fuel Quality is the major cause of Injection system damage. Specifically water and dirt.

dana, been following your super long, multi-threaded cross-forum cavitational rants, (and thanks, i appreciate the hours of research), this is interesting stuff.

to be clear, bottom line: are you suggesting
that conventional SVO filtering (3-day sitting, 10-micron pre-filtering, in-vehicle 5-micron filtering w/ "de-water" filter) IS NOT ENOUGH?

I heard that a 5-micron filter is not actually guaranteed to be 5 micron (just means smallest is 5), unless you buy a LABELED "Absolute 5-micron", which nobody labels, since almost none are "absolute".

I found a guy who sells absolute 1-micron filters... whats your opinion on that... would that help?

since all this cavitation talk has been pretty much over my head, though very interesting...I will address the simpler part of the previous post.

McMaster-Carr sells absolute rated bag filters as do many other vendors. The difference between their "normal" 1 micron and their absolute, IIRC is this:
normal is something like 90% of particles over one micron are filtered.
absolute is 97%.

At one micron, even if they aren't absolute, you are still way under what your normal vehicle filter is probably rated for.

The bigger problem is that these filters are used incorrectly by the vast majority of us, ie - not supported.

-Tony O

quote:

timhon
"to be clear, bottom line: are you suggesting
that conventional SVO filtering (3-day sitting, 10-micron pre-filtering, in-vehicle 5-micron filtering w/ "de-water" filter) IS NOT ENOUGH?"

There are two parts to that answer.
1-In most IPs a standard 10 micron final filter will act as a "safety" to prefiltered wvo..as far as particulate contamination is concerned. Since particulate removal is pretty much the same in diesel fuel and VO conventional diesel filter elements will work well for this application. Most IPs are designed to deal with 10 micron an smaller particulate contamination wihtout wearing out "prematurely". It is actually one of the rare cases where a product engineered for diesel will work for a VO application without modification.

2.But since water exists as suspended microdroplets rarely in diesel and commonly in VO no diesel filter elements will provide the same protection against "water contamination" of VO as they can with diesel fuel. Therefor YES..I am "suggsting"

quote:

that conventional SVO filtering (3-day sitting, 10-micron pre-filtering, in-vehicle 5-micron filtering w/ "de-water" filter) IS NOT ENOUGH?

In fact I have been loudly and repeatedly proclaiming that for years. This "conventional svo filtering" and dependance upon a "dewatering filter" element for water removal while promoted by at least one Kit asssembler simply does not work to keep water from passing through an IP and damaging it as it does.

No filter element currently available removes suspended/emulsified water from wvo. This must be done prior to introducing the wvo fuel to the vehicles tank.

"Owing to the differences in requirements, systems with distributor-type injection pumps use filters with mean pore size of 4...5 um, while pore sizes of 8...10 um are used with all other injection pumps." (Bosch Automotive Handbook, 4th ed, pg 507)
For regular diesel fuel, 200 ppm (listed as 200 mg/kg) water is the max permissible allowed per European Standard EN 590. What's the ppm at saturation? If it's less than 200 ppm, then the difference is "free" water they're allowing. This might be one way to back into some useful information that we could apply to SVO.

johno

200ppm is very small so it must be suspended/entrained water mustn't it? the EN14214 standard for biodiesel and the german standard DIN51606 both allow more, 500ppm and 300ppm respectively, as svo/wvo is more akin to biodiesel than dinodiesel then I would have thought that it can carry more suspended water than dino?

oh yeah if anyone wants to see the standards look Here

Chug

#2 diesel is saturated at about 65 ppm. 200 ppm means that they are allowing about 135 ppm free water.

65ppm water for #2 diesel saturation....thanks Dropout


not much and that is a lot lower than my best guess of suspended water, I will get my coat now then shall I? do you know what the ppm is for saturation of biodiesel?

Chug

The solubility of water in soy methyl ester is approximately 1500 ppm

Cheers Neutral

I remember reading this figure 1500ppm before somewhere any links appreciated? and does this mean that it can take 1500ppm before any free water will be noticed, and will it then be as haze or actually settling to the bottom? as I seem to recall that even at 1500ppm it should be clear.

Chug

I don't have it handy, but there is an older (1995 or so I think) paper by Van Gerpen et al that reports something like 1,200 to 1,500 ppm and suggests that the ASTM water spec be raised to that amount.

I presume that the stated figure is based on some standard temperature like 20deg C, which would mean that esters with 1500ppm would be clear above that temp and hazy below.

Dropout, neutral

do you know anywhere we can find out/read more info on this ppm solubility and temp? and does the 65ppm saturation for #2 diesel still stand? if so does it allow some 135ppm of free water

Chug

quote:

does the 65ppm saturation for #2 diesel still stand? if so does it allow some 135ppm of free water

I sure would like a few links to verify before accepting that figure. Don't have time to find them myself right now...

From everything I have learned ANY free water is "bad" in that it will hasten IP demise. I sure woudl not choose to run VO with the MAXIMUM allowable amount of water in it if at all possible. I really like my equipment to last as long as possible.

quote:

Originally posted by danalinscott:

I sure would like a few links to verify before accepting that figure. Don't have time to find them myself right now...

Don't worry, I found one for you.

http://www.uidaho.edu/bioenergy/BiodieselEd/publication/03.pdf

nice one Dropout

if these figures are correct then the specs for #2 diesel are allowing for up to 150ppm of free water arent they?
and we know free water is not good for our IP's, and yet it seems that #2 diesel is allowed it.
surely wvo must also have a higher ability to hold dissolved water just like biodiesel wont it?

Chug