Are Viton seals needed for SVO?

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Are Viton seals needed for SVO?

Postby Metcalf » Mon Jul 27, 2009 2:55 pm

I was wondering what everyone thought about the need for Viton seals for SVO applications? Needed or not?

Thank you.
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Postby SunWizard » Mon Jul 27, 2009 3:18 pm

That depends on what type of VO. To handle all types viton is best.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Postby jburke » Mon Jul 27, 2009 7:32 pm

I don't think so.
I've had a VW TDI fuel gasket soaking in a jar of SVO for 6 years w/o any sign of degradation.

The only problems I know off are caused by aromatics in the fuel displacing molecules in the rubber.


Non-Viton seals swelled in the presence of high aromatic Low Sulfur Diesel
Then shrank when exposed to low aromatic SVO or ULSD.
The lower aromatics allowed molecules to leave the seal, which caused the seal to shrink and leak.

Non-Viton seals work fine in a consistent aromatic environment.
Ex: LSD all the time, SVO all the time.
Viton is required for a variable aromatic environment.
Ex: running B100 then SVO or ULSD, then back to B100.....
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Postby SunWizard » Mon Jul 27, 2009 8:25 pm

What type is your "jar of SVO"? For a chart, see:
Buna-n (nitrile) rubber compatibility with VO
Last edited by SunWizard on Fri Sep 24, 2010 10:39 am, edited 1 time in total.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
SunWizard
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Postby jburke » Wed Aug 05, 2009 3:34 am

Hi Sun,

The oil is virgin ( 6 years ago ) soy.
I checked the website and confirmed what you state.

However, I have run well over 500 gallons of canola ( rapeseed )
through my '98 VW TDI which I believe has Buna-N rubber seals in the injection pump.
I did get a couple leaking gaskets in the first week, but that was on soy and was due to the prior use of LSD I believe. I replaced the leaking seals with stock Buna-N seals and have not had a problem again in 6 years of a mix of canola and soy.

I don't believe the oil:rapeseed data from that site.
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Postby SunWizard » Wed Aug 05, 2009 8:46 am

I didn't say viton is required, I said its the best to handle all types. If you don't have a leak, I wouldn't do the work of changing any seals. If you have a choice when buying seals, buy viton.

I agree that Biodiesel and blends of it are bad for Buna-N seals, but I don't think its because of aromatics in bio. There is much more going on than simply aromatics, thats why compatibility charts are very common. Here is a good info for Bio:
www.biodiesel.org/pdf_files/fuelfactshe ... bility.pdf

Here is another good site with compatibility charts
http://www.efunda.com/designstandards/o ... %20Oil#mat
Showing Buna-N vs. rapeseed (canola) being only Fair, usually OK for static seals. (most of our seals are dynamic, having moving parts.) Buna-N vs. Soy is Good, both for static and dynamic seals. Note Viton is Fluorocarbon on that chart.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
SunWizard
Site Admin
 
Posts: 1723
Joined: Mon Dec 11, 2006 2:53 pm
Location: N. Colorado

Postby jburke » Fri Aug 07, 2009 5:54 am

"I didn't say viton is required, I said its the best to handle all types."
I agree. My point is that you shouldn't be too concerned if you can't find it.


Viton is often not available for a particular seal.

Also, my conversion is a single tank. The i.p. seals have been in continuous contact with the veg. oil for over 6 years.
jburke
 
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Joined: Thu Apr 03, 2008 10:07 am


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