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Robert's Independent biodiesel tests
Mineral Diesel vs. ABG Biodiesel vs. BIA Biodiesel
Introduction
These tests were undertaken to attempt to understand why my primary electric fuel pump failed and why my secondary pump seems to work erratically when running on B100. I thought that by doing this, I might be able to offer the community some real experience/data. I also hoped to find the cause of this behaviour so I could try and eliminate the problems in my vehicle.
Note: These tests are primitive, but as accurate and objective as I could make them. I have done this to try and find why my fuel pumps have seemed to behave differently with biodiesel to mineral diesel. Some credit must go to Tilly in the infopop forums for his "Dr Pepper Viscosimeter".
Objective
To determine if biodiesel from either of the 2 commercial producers in NSW is more viscous than mineral diesel. Additionally, I would like to determine if the cloud and gel point of these batches of biodiesel is any different to the current mineral diesel. This is being done to attempt to understand why the biodiesel appeared to cause my electric fuel pumps to fail.
Process
Obtain 3 samples in identical quantities.
1. Mineral diesel, as taken from a BP bowser in December (summer diesel)
2. Biodiesel as supplied from Australian Biodiesel Group, which has been sitting in a steel drum for just over a month (and has diesel conditioner added to it about 3 weeks prior). This was also the fuel used when my pumps developed the problems.
3. Biodiesel as supplied by Biodiesel Industries Australia in Rutherford, which was taken from a drum filled from their plant only days before. I have not yet put any of this in my vehicle.
Measure the temperature of each sample before pouring them through a device designed to restrict their flow and measuring the time taken. This should give a crude, but accurate indication of viscosity.
All samples are at same temp before viscosity test.
Secondly, put each sample in the fridge with a temperature probe in one of them and note the point at which each sample becomes cloudy and the point at which they gel.
Samples are put in the fridge with the probe in one to measure the temp.
Firstly, a visual inspection showed that the ABG sample was slightly cloudier than the BIA sample at ambient temp (27°C). However there may be other considerations here: the drum that the ABG sample came from has already been exposed to air a few times as various quantities have been pumped from it; biocide/diesel conditioner has been added to it; the pipe used on the pump which was immersed in it has a coating which oxidised on exposure to the biodiesel – possibly some of this stayed in the drum once the pipe was removed; the drum used may have contained some traces of engine oil in the bottom before it was first filled (the other drum with the ABI sample had already had a load of ABG biodiesel first, so less likely to contain old contaminants).
The ABG sample is slightly darker and more opaque.
The colour of the samples varied slightly, as did their translucence (as noted above). The ABG sample appeared a little darker. The mineral diesel sample was almost clear.
Note the colour difference between the ABG, Mineral and BIA samples
Viscosity test
A soft drink bottle was washed thoroughly and cut open. A small hole was drilled in the lid and then burrs removed to avoid turbulence. The top section was inverted and placed over the bottom section. The samples were each poured into the top section while the hole was plugged. A stop watch timed from the moment the hole was released until the flow stopped and the sample had passed through to the container below. These times were recorded for each sample before each sample was put in the fridge for the next test.
The "Viscosimeter"
Cloud Point/Gel Point Test
All three samples were lined up on a clear shelf in the fridge, with the temperature probe in the middle sample. It is possible that conditions inside the fridge may have made the outer samples colder first, though I think this would be negligible, so I only bothered to measure the middle sample. The door was opened a crack every 10 minutes or so to observe the translucency of the samples and the temperature of the probe.
At 4°C, the BIA sample is obviously gelled.
A closer look at the gelled sample.
The fridge would not go lower than 1°C and the freezer had no light in it, so I decided to stop the tests there. Any observations under this would not really be useful in this current Sydney summer climate.
The 2 remaining samples have still not clouded at 1°C
Results
Viscosity – time taken for each sample to flow through hole (at 27°C)
BIA – 1:59
ABG – 2:04
Dino – 1:57
Same test done after samples at 3°C
ABG – 2:21
Dino – 2:02
Cloud Point
BIA - 8°C
ABG – <1°C
Dino – <1°C
Gel Point
BIA – 5°C
ABG - <1°C
Dino - <1°C
Conclusions
While the cloud point/gel point was much higher on the BIA sample, this make little difference for the time of year that the fuel was made for. Additionally, these points may have been lowered in the ABG sample due to the diesel conditioner which had been added to the drum. I don’t feel that any of this would have had any effect on the fuel pumps, as the temperature at the time the problems occurred was far above the cloud/gel point for all of these samples.
The viscosity difference seems so small to be declared negligible at normal temperatures (about 3.5%) between the ABG and mineral samples. If viscosity increases as temperature decreases (it would seem slightly more with biodiesel), then surely winter with the mineral samples would also have put the same sorts of strain on my pumps? Why did they not fail then? I guess that our mineral diesel is well winterised to cope with such things, so possibly my pumps have never seen gelled fuel before.
The electric pumps that failed could not have been so weak to have burned out at the first sign on resistance (although the pump that did burn out was known to have been problematic earlier.) I would guess that mineral diesel gunk that got flushed from the cleaning action of biodiesel must have got stuck in the pumps first (as both the primary and secondary pumps were before the filter in my vehicle.) This killed my primary pump quickly, as it was already known to be faulty and did not need much to burn out. My secondary pump still seems to run better on B50 and erratically on B100 and this is a mystery which I have still not managed to solve with these experiments.
A specific gravity test would also be appropriate, but I have not the equipment to do this presently.
How can this result benefit other users? In vehicles such as mine, the 2 pumps before the filter is a real weakness. What can people with vehicles like mine do to prevent problems like this from happening to them? Perhaps there are some additives that can be put with dino diesel for a few tanks before using bio. Another option would be to remove the pumps and tank and ensure that the fuel system is completely clean before using biodiesel. Either way, this will deter most new users, so a better answer needs to be found.
The person who can give me the best answer as to why my secondary pump still seems to have problems on biodiesel, but returns to normal operation when mixed down to B50 wins my viscosimeter
), here's my 2 cents worth.
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