Plantoil/diesel conversion basics
Sign up Latest Topics Chat

  Author   Comment  

Posts: 934
Reply with quote  #1 

 Is the information provided by the Beatty report useful to those converting to or currently using VO fuel?


Although the Beatty Report very clearly states that:

It is important to note here that no correlation is suggested between the times required to initiate rapid oxidation reported in this study and “real life” operating conditions nor is it felt that any such relationship can be formulated.
there is some very useful information that can be drawn from the report.
For example:
Oxidation (Auto-oxidation) is a reaction in which Oxygen attacks an unsaturated fatty acid at the Carbon molecule immediately adjacent to the unsaturated site(where a Carbon has a double bond with another Carbon).
The problem with this rapid oxidation in vegetable oils is that the peroxide free radicals produced can and do also react with unsaturated sites to form long chain, cross-linked polymers,

In other words...VO polymerization is a reaction between VO and oxygen. This is a key point to remember if you wish to prevent VO polymerization in VO.  This is not new information to the VO fact it has been widely discussed for years among those who wish to store pre-filtered/dewatered wvo for periods longer than a few weeks. This is why the standard procedure for long term storage of WVO/VO is to fill storage containers as completely as possible to exclude as much oxygen as possible.
Is this the only problem related to VO polymerization?

The most serious problem associated with VO polymerization is crankcase oil solidification. The Beatty Report refers to this as well.
The effect of these polymers can range from the major inconvenience of tank fouling:

To damage of vital engine components:

It is very important to avoid crankcase oil solidification (a picture of this is provided above) since it can easily reduce engine lubrication to the point that catastrophic engine damage results. Similar to the knowledge regarding VO polymerization being an Oxygen driven reaction this is not new information to the VO community either with methods of avoiding this having been discussed for quite a few years on the Infopop VO fuel forum.


A less serious problem caused by VO polymerization mentioned by the Beatty Report is:

the major inconvenience of tank fouling:

This too has been discussed by the VO community for several years and although relatively rare is usually an indication of a VO fuel tank design that regularly heats its contents to a higher than optimum temperature and is either too large or insufficiently baffled..or both. This has been discussed in VO fuel conversion forums for several years as well. Mr. Beatty refers to it these discussions when he states:
the “real life” mechanism is believed to be that of a thin film of oil constantly spashed on tank surfaces followed by a classic drying reaction.
In this case however "drying" refers to an Oxygen driven polymerization reaction rather than the more common meaning of evaporation of water or some solvent from a material. Usually these films of polymerization appear on the hottest surfaces that are repeatedly "splashed" with VO since heat and Oxygen are both present in large quantities..and these are the KEY components of rapid VO polymerization. This polymerized film is often referred to as "chicken skin" since it can reach a thickness of up to 3/16" at which point it resembles the color and texture of cooked chicken skin.  In some cases this "skin" can loosen and be transported along with the VO fuel to the filter..and this can cause the "major inconvenience" that  is referred to by Mr. Beatty in his report since it may on rare occasions require complete flushing of the tank to avoid the necessity of very frequent filter changes.

Are there ANY other problems related to VO polymerization?

Yes..a few...though they are not mentioned in the Beatty Report.
The include:
1.Polymerization of VO left in fuel tanks for long periods while the vehicle is in storage.
2.Accumulation of Polymerized VO inside of IPs in single tank conversions.

Both of these have been discussed repeatedly in the past few years on the public VO fuel conversion forums.
Do metals accelerate VO polymerization?

Yes....but not on their own..and not significantly enough to require avoiding using them altogether. Here's what the Beatty Report says on the subject:

Several factors have been identified as promoting this reaction, they are in order of declining importance:

1. Availability of Oxygen- fuel storage tanks provide an ample supply of oxygen for the reaction.

2. Heat- A rule of thumb in chemistry is that the rate of a reaction doubles with ever 10 deg C increase in temperature, however it has been suggested that the oxidation reaction may even triple with every 10 deg C. (2)

3. Presence of Pro-Oxidants-Some Pro-Oxidants found in Veg Oil systems in order of decreasing activity, Copper, Mild Steel, Zinc, Aluminum. 

Now, tying all of these reactions together, free fatty acids, even thou only sparingly soluble, are carried in any water present and can therefore attack any metals they encounter. These metal ions can then catalyze the oxidation reaction.
(emphasis mine)


The relationship between the amount of water present in  VO fuel and its ability to polymerize has been discussed previously on the public VO fuel forums but until the Beatty Report the actual mechanism that creates this relationship was not known.  Of course water levels in VO fuel need to be kept very low unless one wishes to experience IP and injector damage due to cavitation so those likely to experience the "major inconvenience" of fuel tank polymerization are also the same folks who are likely to be experiencing these much more serious problems due to the presence of excessive water levels in the VO fuel in their fuel tanks. One of the prime rules in using VO fuel is to make certain that total water levels in that fuel is less than 500ppm. My personal standard is 300ppm...since I wish to get the same life from my IPs and injectors as I would were I using petrodiesel.


Clearly if VO fuel is properly dewatered one does not need to avoid metals in VO fuel tank construction. And if one chooses to used inadequately dewatered VO fuel fuel tank polymerization will not be the most serious consequence. Vendors that claim that one type of metal tank is significantly superior to another are simply hyping their product. All metal tanks and tank components have the potential to accelerate fuel tank VO polymerization. Only plastic tanks appear to not have this capability. 


What about warnings of other problems related to increased fuel viscosity?


These appear to be based on nothing but speculation un-supported by the experiences of the VO community as a whole to this point. Beatty states:

It is important to note here that the viscosity increases did not begin until late in the oxidation cycle and therefore might not be of concern in real life conditions.
and I would tend to agree. 



What about the recommendations/conclusions Beatty made at the end of his report?


These appear to be unsupported by any of his data..and directly contradictory to  his statement at the beginning of the report

It is important to note here that no correlation is suggested between the times required to initiate rapid oxidation reported in this study and “real life” operating conditions nor is it felt that any such relationship can be formulated.
as it appears he is not only speculating that a "real life correlation" DOES exist despite fairly obvious evidence it does not..he appears to be transitioning from a scientific study directly to an advertisement for the product he hoped to market at that point.


The addition of antioxidants and metal deactivators could also be quite helpful in minimizing this risk.









Previous Topic | Next Topic

Quick Navigation:

Create your own forum with Website Toolbox!

This forum is brought to you by A proud sponsor of Invest in the future.