Back flushing diesel into WVO filters to remove glycerin.

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Back flushing diesel into WVO filters to remove glycerin.

Postby Performance Plus WVO » Thu Jul 03, 2008 11:32 pm

The Question has came up on this forum why diesel should not be introduced into the WVO filter. The argument is the dirt will keep recycling to the WVO tank. I would like to suggest the filtered oil should be cleaned to a finer micron than the fuel filter on the WVO side of your vehicle. The reason being is then a person should only need to worry about two things clogging your WVO fuel filter on the vehicle. One is glycerin or slime build up on the filter "wich can be removed by flushing the filter with diesel to an extent". The next would be poly and might be mitigated by some diesel returning to your WVO fuel tank. One benefit I like to attribute to purging a small amount of diesel into the WVO suction line and filter, is when a person initially switches from diesel to WVO the diesel may act as a buffer dilluting the WVO slightly to lower the vicosity putting a smaller load on the IP. My belief and it is a belief because I cant see a IP working from the outside. Is it is much easier on the Ip if the initial switch over contains some diesel. This may help prevent "shocking the Ip in cold weather". Does any one have an opinion on my theory in trying to prevent thermal shock by introducing some diesel into the WVO side.
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Re: Back flushing diesel into WVO filters to remove glycerin

Postby hheynow » Fri Jul 04, 2008 8:11 am

Performance Plus WVO wrote: One is glycerin or slime build up on the filter "wich can be removed by flushing the filter with diesel to an extent". The next would be poly and might be mitigated by some diesel returning to your WVO fuel tank.

Does any one have an opinion on my theory in trying to prevent thermal shock by introducing some diesel into the WVO side.


Are you sure it's glycerin? How can glycerin drop out just with heat? I've never heard of it separating from VO EXCEPT in making bioD. Slime? Are you're de-watering your oil? Do you remove the fats from the oil? Are you using PHO?

My opinion on using the same filter for #2 & VO is it's not the optimal setup. I had it set up that way until I saw the light and decided that separate filters was better.

If you want to prevent thermal shock run your #2 through the FPHE as well. Introducing diesel has nothing to do with "thermal". I'd think the cold #2 on a very hot IP is thermal shock.
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Postby Performance Plus WVO » Fri Jul 04, 2008 9:17 pm

It seems most people shear their IP shafts when they switch to WVO from diesel on a cold day not the other way around. This has been my experience with 22 sheared IPs from customers conversions that were not done correctly. I have never heard of the cold diesel locking up a IP. The most common IP's to reach failure are rotary. The rotor locks into the larger massed barrel. The rotor which has smaller mass therefor will change tolerances more readily due to a temperature change of cold or hot. The rotor on the pumps I have seen fail have been from poor lubrication,cavitation and finally to high of a viscosity load. There have not been any cases reported to me in person of diesel that is injected cold into a hot pump having caused any issues. As far as two filters better than one I agree. The glycerin in my wvo may not be glycerin I dont know how to test its chemical make up. It may be fats that dont melt although I cold filter out of my centrifuge at 10 psi so in my mind the fats should have been removed. The chemical compounds in the waste oil I use as fuel are wide and varied it could be melted latex gloves for all I know. Point being something of foreign material gets stuck on my filters and if I back flush with diesel they last a lot longer without harming my motors.
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Re: Back flushing diesel into WVO filters to remove glycerin

Postby Johnh » Sat Jul 05, 2008 8:25 am

hheynow wrote:Are you sure it's glycerin? How can glycerin drop out just with heat? I've never heard of it separating from VO EXCEPT in making bioD. Slime? Are you're de-watering your oil? Do you remove the fats from the oil? Are you using PHO?

Quote from "Chemistry and manufacture of Hydrogen" in a chapter refering to Hydrogenation of vegetable oils. (chapter 11,page 36)
"Thus when such steam is blown through Palmiten the following reaction takes place
Palmitin + steam = Palmitic acid + glycerine
or for Olein
Olein + steam = oleic acid + glycerine
(Chemical symbols removed because they are not pertinant here)
This was to remove the glycerine prior to hydrogenation for conversion to stearic acid.
So it seems that there are other ways to remove glycerine from vegetable oil other than biodiesel.
Regards
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Postby hheynow » Sat Jul 05, 2008 8:38 am

Johnh...steam! :roll: Can you turn pyrite into gold? :mrgreen:
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Postby John Galt » Sat Jul 05, 2008 12:06 pm

There is no free glycerin in VO. What's clogging the filters is most likely PHO and animal fats.
The subject line chosen indicates a misunderstanding. The author might want to edit the subject so they don't appear quite so silly.
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Postby Performance Plus WVO » Sat Jul 05, 2008 12:31 pm

Yeah Mr Galt you are problably right it must be fats that are clogging my filters beacause indeed you do know my filtration process. Let me give you an thought to chew on. I centrifuge the oil in a DC for 2 days @ 95 psi @ 200 degrees. The rotor is clean when I am done. The oil is filtered cold @ 50 degrees through a 10 micron and then a 5 micron filter @ 10 psi and put into poly drums that are full then sealed. So maybe just maybe you can explain where the animal fats are coming from ? Could grill cleaners be causing a chemical reaction to make the glycerin drop out in my oil? I got 12,000 miles out of my last wvo filter @ 12 miles per gallon. Galt how many did you get ? And yes I did back flush. So If you would explain where the fats are coming from other than thin air it would be appreciated. Has any one else seen a thicker layer on the bottom of a container of well filtered and dewatered oil?Thanks MR. Silly
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Postby Johnh » Sat Jul 05, 2008 12:45 pm

And Mr Galt I think you didn't read the question I was replying to.
I was not suggesting there was any free glycerine in WVO the comment was made that Biodiesel production was the only method he had heard of for glycerine seperation from WVO. I was showing that there are other instances of this occuring, and could in fact occur at deep fryer temperatures if water is introduced.
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Postby John Galt » Sat Jul 05, 2008 3:40 pm

The high processing temperatures are melting the PHO & fats, and the CF gets them very clean. However once they're in the fuel system, any part of that fuel system that cools below 65-70°F will see the very clean fats and PHO separating out.
Has any one else seen a thicker layer on the bottom of a container of well filtered and dewatered oil?

Yes, this is a very common problem with those who use heat for processing.

My comment about glycerin was directed at message #1
a person should only need to worry about two things clogging your WVO fuel filter on the vehicle. One is glycerin or slime build up on the filter

There is no free glycerin in VO to clog filters.
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Postby SunWizard » Mon Jul 07, 2008 2:23 pm

I agree there is no glycerine and it takes a specific chemical reaction to create it. It sounds like poly VO clogging the filter which is very common, and no one has mentioned it yet.
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Postby Radrick » Tue Jul 08, 2008 4:08 pm

Performance Plus WVO wrote:It seems most people shear their IP shafts when they switch to WVO from diesel on a cold day not the other way around. This has been my experience with 22 sheared IPs from customers conversions that were not done correctly. I have never heard of the cold diesel locking up a IP. The most common IP's to reach failure are rotary. The rotor locks into the larger massed barrel. The rotor which has smaller mass therefor will change tolerances more readily due to a temperature change of cold or hot. The rotor on the pumps I have seen fail have been from poor lubrication,cavitation and finally to high of a viscosity load. There have not been any cases reported to me in person of diesel that is injected cold into a hot pump having caused any issues. As far as two filters better than one I agree. The glycerin in my wvo may not be glycerin I dont know how to test its chemical make up. It may be fats that dont melt although I cold filter out of my centrifuge at 10 psi so in my mind the fats should have been removed. The chemical compounds in the waste oil I use as fuel are wide and varied it could be melted latex gloves for all I know. Point being something of foreign material gets stuck on my filters and if I back flush with diesel they last a lot longer without harming my motors.


I am in the process of setting up a 6.5T chevy to run wvo in very cold climates. I have done allot of research on the topic of IP damage and I have come to the conclusion that it is not thermo shock that causes the damage. The shaft and housing in the Stanadyne rotary IP runs a very tight clearance in the range of .0002. This area of the pump both relies on the fuel as it's only lubricant and relies on the tight clearance to maintain proper pressures in the chamber directly adjacent to it. In my opinion this setup is not sensitive to temperature change at all but is very sensitive to fuels that are too thick to sheet out and provide the required lubrication in this area of the pump. I believe this situation is not caused by temperature change but by the lack of heat in a possibly very small section of wvo hose just in front of the IP or by the super cooled IP over cooling the wvo as it enters the IP on the initial switchover. I believe the fact that both of these scenario's can only happen at switchover has caused the common belief that this IP is sensitive to thermo shock. Just my $.02
1995 Chevy K1500 6.5 TD not on WVO yet but soon.
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Postby Performance Plus WVO » Tue Jul 08, 2008 5:48 pm

Radrick your theory makes sense to me. The best way I have found to protect damage to this style "Rotary pump" Is to do as follows. I am not shure how to draw a diagram and put it on here. Rather I will try to explain flow procees of the systems I build. When I purge the excess wvo is pushed into the wvo tank by diesel. I purge on a closed loop. The purge is not 100 percent effiecent so some diesel is returned into the wvo suction line. In my opinion this blends the diesel and wvo so the viscosity is not as high in initial switch over. I live in a climate that stays in the low teens for much of the winter and will go as low as 20 below zero. When I switch in the morning on a really cold day I do not switch at 100 percent warm temp of 175 rather I will switch @ 125 wich seems to be easier on the pump I do this @ idle and let the oil circulate for approx 45 seconds before re applying throttle. I have personally only lost one IP and that time I had switched @ 85 mph full throttle 175 degrees and it was 2 seconds later I heard the shaft shear and the rest is history. In my opinion it is important to have some blended diesel in the vegetable oil just right as it first enters the pump to provide as smooth as a transition as possible. This is my opinion I am shure others will think differently but I have not had any switch over problems in a few years now using this technique every day. The down side is you use a little more diesel than if you did not purge some diesel into wvo suction but its pretty cheap insurance. The diesel back flush is restricted more during summer as it seems not as critical. Hope this helps replacing an IP on a GMC sucks dont ask me how I know. For that matter replacing any IP sucks but I think you will have less problems if you are cautious with your switch over habits. I know that it has helped me.
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