Corrosive properties of Biodiesel

[250downunder]

Following a brief discussion re the corrosive effect on cadmium plated screws left in Bio, I have commenced a basic test using samples of Copper, Aluminium, and Cadmium plated steel.
The Biodiesel used for the test is derived from used Soybean oil, water washed until the effluent is PH neutral. 100ml./100L. of Chemtech Diesel Power is added.
The samples have been measured so as to note any loss via corrosion. I will check and measure the samples monthly and report any effects.
After one month:-
Copper - no visible or measurable effect.
Aluminium - no effect.
Cad. plating - no effect.

[gilfish]

Re: Corrosive properties of Biodiesel

An interesting test 250, I believe that properly made ASTM spec and dried esters should not cause any corrosion at all? if it has any impurities at all it will.
It might be a good idea to check the TAN number and keep an eye on that as well, as your bio oxidizes it may become more corrosive. Keep us posted
regards andy

[Tony From West Oz]

Re: Corrosive properties of Biodiesel

250,
Are the samples submerged in the biodiesel?
I suggest that a test where samples are partially immersed in the biodiesel will show any issues at the air/biodiesel interface.
Is the temperature being controlled? Please record the temperature as this will provide an indication of the rate of any corrosion at higher temperatures (chemical reaction speed doubles for 10C increase in Temperature.

Keep up the good work.

Tony

[250downunder]

Re: Corrosive properties of Biodiesel

The samples are only partly submerged in Bio, so any changes can be easily seen and measured.
The test sample is open to the atmosphere and is currently only subject to ambient temperature. If no corrosion is evident after a few months I will consider raising the temperature.
Total Acid Number testing is beyond my limited capabilities.
I am trusting that the Chemtech additive that I use may help to limit oxidation [and the nasties that result].
[Baynox Plus would appear to be the stabilizer most suited for use with Bio, but it is difficult to source].

[250downunder]

Re: Corrosive properties of Biodiesel

After almost 4 months there is absolutely no sign of any corrosion of any of the materials being tested.
I am prepared to accept that properly washed & dried Bio has no corrosive effect on most metals.

[Qwarla]

Re: Corrosive properties of Biodiesel

That is nice to know, and is how I thought it should be.

As you said properly washed & dried Bio has no corrosive effect, one can only wonder what it may be like straight after seperation.
You do hear of people that take the bio straight after seperation, filter and use.

[250downunder]

Re: Corrosive properties of Biodiesel

Perhaps I should repeat the test using unwashed Bio.

[Captaincademan]

Re: Corrosive properties of Biodiesel

I totally forgot I said I would have a crack at this too, sorry for my lack of input. I'll go round up some bits and pieces now and put something together as well, as I don't wash my Bio, so it will be a good comparison. I'll try to add some more metals to the three above as well.

Attached sheet has the info on test.

Cheers,

Cade.

[Captaincademan]

Re: Corrosive properties of Biodiesel

Ok, 5 days in and no changes to any of the metals except the copper. it has cleaned it up (a bit). it appears that it has removed the tarnish a little.

watch this space.

[Captaincademan]

Re: Corrosive properties of Biodiesel

3 weeks in and no change to any of the submerged metals. Copper hasnt got any worse. Only thing worth mentioning is the brass thread above the bio where the bio has crept up the thread (capillary action I presume) has started to leach out some copper (gone green). No corrosion visible to sumerged brass.

I am thinking that the cad plating on the old fuel filter of mine that sparked this thread wasnt really cad plated at all. maybe it was just some form of paint? The cad plated spanner thingy has shown absolutley no signs of degradation.

[Matt]

Re: Corrosive properties of Biodiesel

OK is isn't metal but put in a Toyota fuel sensor and watch the varnish break down. I hate varnish and Peugoeot and their rubber seals, I spend my life fixing both these thing. I can add that B100 tens to gum up on CAD plated pipe.

Thanks you every one fopr your findings,

[Captaincademan]

Re: Corrosive properties of Biodiesel

OK 5 months on now, and I have some results.

See attached PDF.

Note:

1. early on in the piece, a raccoon or something knocked over the aluminium test jar. so no results on that one.
2. Cad plating shows serious signs of degradation. cad plating can be easily rubbed off the base metal with your finger. I think there may be differing degrees of quality of plating though, as it does not really resemble the affect seen on the old filter. Bio clear and clean, close to original colour
3. Copper - nil affect. it looks a bit different, but it is only a very minor tarnish. bio clear but slightly tainted in colour
4. Zinc plating - midly affected. can rub zinc plating with finger and it appears to start to remove. definitely affected though. bio slightly cloudy
5. Brass - nill affect. bio coloured green due to copper leaching, but clear
6. Steel - nil corrosion advancement. Bio coloured red due to rust staining, but clear
7. Galvanising - Badly affected. completely disolved and removed from base metal. cloudy bio with grit in the bottom.

So from the above, copper and mild steel are fine. (we knew this anyway) Cad plating and zinc are affected over time. initially though there was little change, it took several months to become evident. Galvanising is a complete write off. I would say it would be a complete disaster to use unwashed bio in a system that had galvanised components.

I hope this was of some help.

Cheers,

Cade.[IMG][/IMG]

[Captaincademan]

Re: Corrosive properties of Biodiesel

kind of surprised that my last post here didnt get any hits. I thought it might be useful to users of bio, especially those who do not wash. heres a bump incase it was missed.

[Bueff]

Re: Corrosive properties of Biodiesel

Okay I go first than

Thanks guys for putting your time into the testing, I am not going to go into the wash or not to wash discussion, but I do wash (my bio) and what comes out after it.... well, you don't want to imagine that going through your engine

[Matt]

Re: Corrosive properties of Biodiesel

Zinc type plated?