The fact that you can't properly measure pH in an oil seems to me to be not a liability but an asset. I earlier used the word "alkaline" rather than "high pH" to describe unwashed biodiesel. This was a deliberate choice of words. Something which is dry and alkaline has only the potential to raise pH. It can do nothing in the absence of water from which it grabs hydrogen ions and thus raises the pH.
We really need a corrosion chemist to come on this forum and check out some of this theory. The experience of people like yourself using unwashed biodiesel with no reported corrosion suggests that the motors are experiencing this BD as dry.
If you don't wash the BD it will of course be pretty dry: what little water it started with will be largely extracted into the glycerine layer with which it has a much higher affinity. The minute amount of water still present will be fully dissolved and remain fully dissolved even at low temperatures.
BD which has been well washed should have little ability to corrode aluminium even if damp, but poorly washed material might have a considerable amount of soap and considerable potential to cause corrosion. We know that BD which appears dry (perfectly clear) can have water come out of solution (visible haze) if cooled.
This ramble has lead to the thought that if you are going to wash the BD it had better be reasonably well done or, if not well done, the BD should be dried.
Could it be that as long as no water haze is visible there can be no corrosion?
Where is that corrosion chemist?
Many people on this forum say don't agitate hard, having had bad experiences with emulsions. I think you have hit on the explanation for this: it is as you say "water, air and biodiesel forced together". Of course an emulsifier must be present to stabilize the bubbles but an emulsifier is present, soap. That is why the wash is being done.
You also report that the white stuff floated to the surface after some time standing. If it was formed on the surface it must have sunk before it floated. I think that is easily explained. It is rather like bubble washing in reverse. Initially the glob has a lot of water in it and it sinks. after a while some of the water is released and it floats to the surface.
I think your observations might have application to other methods of washing. The usual advice "don't stir too hard" could be refined to "don't stir fast enough to create a vortex". Clearly a vortex would wrap air into the mixture.
It is air that is the culprit and your mist wash seems to be a pretty foolproof way of washing without pulling in air.
Yes I am a bit of a corrosion chemist. As a former electrochemist, (electroplating, electroforming, aluminium anodising) I understand the galvanic corrosion principles, ion transfer etc...
"NEUTRAL", you said it all in your first paragraph (4 th of december) POTENTIALLY ALCALINE. However this potentially alcaline solution is highly hygroscopic (hungry for H Ions) and the free surface of fuel in the tank would be in contact with athmospheric air, agitated and likely to pick up moisture. The resulting emulsion would be alcaline enough to worry me on the long term effect on aluminium. In a humid tropical climate it wouldn't take long. The Ester being also an oxygenated molecule is also corrosive but in an acidic way this time... Mild alcalinity should have no effect on steel. I would rather err on the slightly alcalin than on the mildly acid.
Can a sturdy Diesel mechanic tell us here what metals are found in the fuel path of a typical injection pump?
We seem to be getting somewhere at last on this topic. A question for you.
Given the hygroscopic nature of BD, water will be drawn into the material as you say. Initially however the water will be well below saturation level and the BD will remain perfectly clear. At a constant temperature and humidity the water absorption will slow and eventually cease. At no time will the water content exceede saturation and come out of solution. The BD will remain clear indefinitely - no haze.
The question is this: can this BD cause corrosion when the water is not free but dissolved? Would it be necessary to cool the BD so as to exceede the saturation level and produce a water haze before corrosion could occur?
Neural and Wotanozzle
You have both raised some interesting and informed
comments,as a diesel mechanic, I will add i hope some insight on the common fuel transfer systems used and the metals in use .I am not a metallurolist so the % of the alloy metals and variations used on differnet makes I can not comment on.
Firstly the BD does not sit around in the tank for any length of time (if it is used daily) so does not have much chance to absorb moisture,the fuel is constantly (in most cases) being circulated through the injector pump and heated before being returned to the fuel tank in a heated state therefore keeping it dryer.
The fuel lines are usually made of mild steel and often have an anodised alloy on the internal and external surface to prevent corrosion,I am not sure of the material used but possibly a mix of zinc and alluminium.Various rubbers are also used to isolate the engine line from the chassis line.
As stated the fuel lift pump and filter housing is usually alloy (alluminium )with hard carbon steel working parts as is the majority of injector pumps components,however latter rotary pumps use some carbon fibre and plastic components as well.The tank is usually mild steel sometimes with a anodised interior .Injectors are almost always High carbon steel in a mild steel case all compression parts are highly machined case hardened with tungstun alloys
My experiments have shown that BD degrades the strength of carbon Fibre components .This was evident using a small Davies pump with a Carbon Fibre impellor and housing and this product became soft and cracked with a breakdown of the surface polish,I still use these pumps but wash it with water or oil after use.
Again I have seen no degradation in alloy components used in the Engine with the use of BD.
Gauses and filters components in the fuel line are usually stainless steel,plastic or high carbon steel and pape
LONG TERM CORROSION
I want to be corrected if I am wrong but in a cocktail of different metals, zinc and aluminium being strongly electronegative to steel would go first in an aqueous electrolyte, the only ones that I am used to, that is all electroplating solutions acid or basic, sea water, soda water, holy water... All are conductive to even minute currents. However if that warm unsaturated Ester is what I believe it to be (but no proof yet on that) NON CONDUCTIVE corrosion shoud be very minimal indeed. However, when cooling overnight or left sitting for a while, a precipitate of aqueous alcaline solution could form on the bottom of any volume filled with biofuel, including that lovely, cherished piece of engineering that is your fuel injection pump! Let's get the stuff strictly neutral in the first place. Perfectly dry, I think is impossible. Anyhow, trying to achieve the PERFECT biodiesel is like chasing the woman of my dreams, I finally gave up and I think a good damage-control assessment would do well instead. Such as testing the differents metals concerned (and by the same token rubbers, viton, pvc's etc...) in differents biodiesels that are likely to be produced by an ordinary kitchensink chemist with reasonably inexpensive gear in an acceptable delay. (Sorry Grand'ma, I nicked all your jars)... Any loss of lustre on a machined steel part or polished alloy means micro pitting. It can be put to magnification ( Old kelner lens from a ruined pair of binoculars give the right power). Party immersed parts would give a better reading by contrast. Patience, yes but one thing is sure: next year I will be one year older, wether or not I put those things in the jars..
By the way, hintertech, carbon fibre shouldn't be attacked by the Ester but the bender must be some polyester or epoxy that is...
sorry for misspelling your name ,I just discovered my mistake
I think 007 is better.
Tilly SBC/IBA What's in a name Div
Why do kamikaze pilots wear helmets?
TL, have tried washing using warm/hot water but it produced too much emulsion and a very white wash water. Try washing using water unheated straight from cold water tap.
If the BD did not solidify or become noticably more viscous at 40 deg F it should be OK to use at that temperature.
Any ideas on reducingthe amount of white stuff that forms when washing?
I did a second batch 12/7. I could not get a good titration read. Digital ph tester always inaccurate because of oil, The pheno I had I think was to old and would not read.
I increased the NaOH from my first batch 5.2g/l to 6.0g/l. Using 20% methonal and about 38l of WVO to process, ( the oil is Hydrogenated soybean with citric acid and silicone per the box and is changed every 24 to 48 hours. )
I ran the batch through a pump/static mixed for an hour. I had a lot more glycerine this time and it turned solid within 24h, the glycerine was still liquid from the prior batch.
Sat night was the first wash using cool water mist, about 10 gal. Sun did 2nd wash and started to see white/butter looking floaters, wash water still milky looking with anouther 10gal, later Sun afternoon did 3rd wash and the same thing, Floaters and Milky water.
I gently added 5 gal of water and added a bubbler over night.
This AM I had a lot of these floater, but the BD looked very clean, I drained out the milky water and filtered out the oil, cleaned out the white goo and did one last wash. the water was clear.
It seems that these floater want to change the water to a milky color when washing till removed.
I have not tried the cold test on this batch yet. The prior batch would start to get cloudy with little snow looking flakes in the batch when below 40F. I'm leary of using because of the night are below freezing and with a 20% BD mix not sure what will happen.
try not washing
1st do not worry bout the floaty white stuff it will either break down in the bd or you can heat the bd and it will go away this stuff is made up of water soap air and bd and is mainly produced when you allow the BD to get too close to the spray nozzel solution use a deeper container for the wash ideally the container should be able to hold the full amount of BD you are to wash AND the full amount of water at a 1 to 1 ratio that is for every 1 litre of BD you wash with 1 litre of water the container should al;so be deep enough for you to allow at least 12 inches between the washed BD and the nozzel using a 1 to 1 ratio that is a container deep enough to haold 38 litres of BD and 38 litres of water +12 inches at least seperationfrom the MIST nozzel
What is happening is that the BD is getting tooo close to the nozzel and the spray is NOT misting enough at this range ,SO you are INJECTING water and air into the bd and stirring the soaps this in turn sinks to the bottom of the tank BUT eventually the air saturates the mix and it floats to the top of the drum
I have done this deliberatly as a demonstration so as to determin what happens and how to fix
the fix is to either add salt to the floaty white stuff this will cause it to break up or when you are finished washing and go on to drying heat the BD and again the floatys will break down or just let them break down in the BD either way it is only soap and biodiesel at the end so ther is no cause for concern if you are really worried about it just scrape it off the surface and keep it to one side and watch what happens..
NEXT milky wash wat NO WORRIES this is exactly what should happen the milky water id the soaps and impurities that you want to remove that is why you are washing in the first place using a 1:1 ratio will speed this up in the first wash and the second wash water should be much less milky in fact almost just a white haze by setting up another barrel and collecting this water u can either use it again to remove additional crap or use it as the first wash water in the nect batch all you need is a small pump and a hose conection to your washing MIST nozzel
the more of the white milky water you get out the more soap you are removing this is nothing to complain about it is what you want the MIST system produces this because it is more efficient at removing soaps that bubbles BECAUSE you are using bigger water droplets than is produced by a bubble which produces only MICRO droplets which take much longer to do the same job.
IF you must use a bubbler system and I whould NOT be very sure that you remove all the previous wash water including a layer that may be more creamy and airaited this layer will cause you heaps of trouble if left in the BD and bubbles are included
finally you might need to leave the BD overnight to allow full water settling but this would be rare heating the BD will remove any water still held in suspension sometimes soaps will gather on the bottom of the tank if you have produced floaty white stuff and heated the BD in this case decant most of the BD till JUST enough is there to hold the soaps and filter it off using a coffee paper filter them add the remaining BD to the rest of the batch
FLOATY WHITE STUFF IS NOT A PROBLEM it is just AIR, BIODIESEL, SOAP, AND WATER
my final word this has been described in this string so if you go back from this point and read what is already tabled you will see this information and some answers to it
BC inventor of the MIST WASH SYSTEM
Looks like I need to find a larger tank to wash in. I know at one point I was getting some of the spray mist into the BD.
I'll make this change on the next batch.
I have about 2l of unwashed BD from this batch and 2 night ago i chilled to 38F and now have a layer of white stuff between the glycerine and BD.
It's been at room themp for a day (68F) and has not disolved back. Could this be a layer of soap?
If there are esters in your BD made from tallow (animal fat), they will solidify and settle to the bottom before many veggi esters, typically around 15 deg c. These are referred to on this forum as "High temp tallow esters".
They will then remain solid until they are heated to around 40 deg c,. Above 40 deg c they turn back into a liquid. This is biodiesel, not soap.
A good way to confirm that this layer of white is the high temp tallow esters is that if you gently move the bottle of BD around the white layer moves in a whispy smoke-like fashon.
I have never seen a layer of soap in the Biodiesel. I think the soap jst becomes a part of the glycerine layer and if you make much soap you have an increased layer of glycerine.
Tilly SBC/IBA Talow div
Tilly visable soap will form in biodiesel if one tries hard enough to do it, it will settle to the bottom of the biodiesel and can be then removed with fine paper filters, I am doing this at the moment. Under some conditions it will be fairly solid and if a little heat is introduced will liquify.
as for your other answer to the other question I believe that you hit it on the head about esters
TL if you have 2 litres to spair then use this in the existing container to test out your misting system if no floatys appear you need a bigger unit and remenmber use a ratio of 1:1 and NO acids
same thing used to happen to me with the hose nozzel too close..bc is right with the mist distance ,,if you get a 44gal pound the bottom a bit conical weld a valve at the bottom and prop it on bricks that wouls solve your vessel prob..i use 2 of these.
I have in front of me my original 1 ltr test batch. This has settled out , after about three week in a room that gets down to 5 c to four distinct layers.It is in a Dr Peppers bottle and the top 141 mm is very clear bd. the remaining 29 mm consists of a dark caramel coloured layer with a 3 mm layer of white waxy stuff suspended about half way down.The shape of the bottle bottom "crimps" make it awkward to ascertain the exact proportions of this last part. Am I right in assuming that the dark stuff is the glycerine and the white is hight temperature fatty esters ?
To make sure, just gently swirl the bottle around, and if the white layer moves around in a whispy fashion, acting as if it is almost the same weight as the BD then it is the high temp tallow esters.
Tilly from Paradise.
Hi all - a query regarding the washing of mini batches as per the Patended Dr Pepper procedure.
When I have done these with new oil at 20/3.5 I get a lovely reaction with good separation and lovely clear BD.
To wash the BD I have been decanting off the Glycerine and then gently running in about equal parts of tap water to the BD.
The problem is that the previously clear (honey coloured) BD washes OK to a nice lemon colour however it goes a bit hazy - is this OK? What is the haze? I am presuming it is very small water droplets as the wash water ends up clear after about three goes. I am going to warm the combined (3) samples to see if they clarify before I try them in the tank.
Can anyone confirm why they go a bit hazy and how to clear them?
Sunny SE Qld
yes you are correct they are water particles, if you leave the bd for a day during hot weather it will clear if u dont have time for this heat to about 60d C and it will clear heating over this will dry the bd but u will have to go up to 120d C and keep it at this till the steam stops
I other heat tyo 60-80 dC then decant off the top 1/2 bd at least then dry the rest
If you have the time do the following
wash bd about 20 litres then
heat in a drum till about 60 d C then
carefully look inside the drum and u should see water drops collecting on the bottom of the drum under the bd
eventually all/most of the water will drop to this layer and you will have clear bd above the water down below needs to be steamed off if you want all the bd or
decant off the clear bd till u leave a little bd but all this water then add this contaminated bd to the next wash. you still have it but doing this will help speed up your recovery of good bd
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