Sorry - my fault.
Tests run by Exxon showed that, compared to reference
diesel fuel in 1993, a 20% blend of Biodiesel had
significant, quantifiable improvements in reducing wear
(193 micron scar for B-20 vs. 492 micron scar for
petrodiesel) and friction (0.13 micron scar for B-20 vs.
0.24 micron for petrodiesel) while improving film coating
ability of the blend (93% film with the B-20 vs. 32% film
with the petrodiesel). The B-20 blend compared
favorably for lubricity results against Exxonâs own
lubricity additive.
The SWRI results for the BOCLE tests confirmed the
earlier Exxon study results. Low sulfur, low aromatic
("CARB") diesel was compared to various blends of
Biodiesel (soy methyl esters). Data were presented in
values of grams of weight added to the apparatus before
failure of the fuel to adequately lubricate the metal. The
higher the weight the ball could support, the better the
lubricity of the fuel. Neat petrodiesel (low aromatic
CARB) had a BOCLE result of 3,500 grams, whereas the
neat Biodiesel had a BOCLE result almost twice as high
at 6,100 grams. The B-20 blend had a BOCLE result of
4,100 grams, close to the value for pre-1993 (high
sulfur, high aromatic) petrodiesel fuel. In concentrations
below 5%, the Biodiesel had no measurable effect on
the lubricity of petrodiesel.
Follow up BOCLE studies at SWRI in 1996 concluded
that Biodiesel methyl esters had even better lubricity
properties than previously reported. The Biodiesel
(RME) had a BOCLE value of 7,000 grams vs. 4,250 for
low sulfur diesel (not CARB diesel), and the B-20 blend
had a BOCLE value of 4,600 grams. Scar wear
diameters were also encouraging, with a 405 micron
scar reported for petrodiesel vs. a 190 micron friction
scar for the B-20 blend.
Subsequent field studies on light duty truck engines
(5.9L Cummins diesel at the University of Idaho) have
corroborated these results by finding an "absence of
wear" and friction scars on engines broken down for
inspection after a 100,000 mile road test running on 28%
Biodiesel. In a University of Idaho durability test (1,000
hour tests on small diesel engines), it was found that
methyl ester Biodiesel was equivalent to no. 2 diesel on
the basis of long term engine performance and wear.
The primary factors evaluated in that study were engine
brake power and torque, injector tip coking (carbon
deposition), and engine component wear based on oil
analysis.
In house monitoring over the past 5 years of our "Biofuel
Test Vehicles" (a Mercedes Benz 300TD diesel station
wagon and a 1985 BMW 524-Diesel) at CytoCulture has
shown no evidence of unusual wear or polymerization of
engine crankcase oil (analysis performed by Herguth
Laboratories, Vallejo, CA) after more than 40,000 miles of
operation on 30-100% blends with Biodiesel.
This is quite interesting, unfortunately something happened to
the latter part of the message, please do
post the rest.
I might add that in looking over the specs for various veggie oils,
I see little difference between
cottonseed oil and rapeseed oil, perhaps someone could enlighten
me on this? Is there a difference in
lubricity? The iodine levels at least are pretty much the same.
On Thu, Mar 21, 2002 at 02:54:08PM +0100,
[EMAIL PROTECTED] wrote:
> Here's something on lubrication from the Technical Handbook for
> Marine Biodiesel in Recreational Boats
> Lubricity Properties
> Biodiesel has been studied extensively in Europe and
> the U.S. for its effect on long term engine wear,
> particularly with respect to those components normally
> lubricated by the fuel itself. Fuel pumps and injector
> pumps depend on the operating fuel for lubrication of
> moving parts and shaft bearings. Initial work on the
> lubricity of Biodiesel, performed by Mark-IV Group and
> the Southwest Research Institute in 1994, established a
> clear advantage to blending Biodiesel with petrodiesel to
> achieve superior lubrication.
> Lubricity properties are measured at the Southwest
> Research Institute (SWRI) by a "Ball On Cylinder
> Lubricity Evaluator" (BOCLE) machine to measure metal
> to metal hydrodynamic wear simulating rotating shafts
> and bearings. A static steel ball is loaded onto the edge
> of a rotating disc and the diameter of the subsequent
> scar on the ball is measured (similar reciprocating
> machines exist in Europe to measure scar on a steel ball,
> and newer versions have been developed in America to
> improve lubricity measurements). The BOCLE test does
> not measure adhesive friction wear.
> Tests run by Exxon showed that, compared to reference
> diesel fuel in 1993, a
> T
>
>
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