Zebrafive
Super Member
Viton or Buna-N? Which is better for hydraulics? Viton costs more, is it worth it? Planning on stocking up on ORFS and ORB O-Rings.
O-Ring material
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crazyal
Super Member
Is there that much of a difference in price? Off the top of my head I would say Viton is probably a better choice as it tends to have a higher chemical and temperature resistance than Buna N.
alchemy
Bronze Member
This was at wiki
"Viton o-rings are the only known solution to the pervasive use of Buna-N seals in many popular BMW automobile engine variable timing units, known as VANOS. In the VANOS, the Buna-N o-ring deteriorate while the Viton fluorocarbon o-rings have similar functional characteristics to Buna-N, but with much higher temperature and chemical resistance characteristics."
That probably is not a good comparison for tractor hydraulics. My german car has valve timing advance which I assume is what they may be talking about and the only thing I can imagine contacting the seals would be heat and motor oil. If that is the case then you would think viton would be better. On the other hand I was surprised to read elsewhere that viton is not great with solvents other than hydrocarbons. I think hydraulic oil is hydrocarbon but oils have different properties than light hydrocarbons like gasoline etc.
Interesting question. I'll check further. There should be a chart somewhere.
alchemy
Bronze Member
Found this chart. Ill be keeping this one handy myself since it has alot of materials and resistances. It does include hydraulic oil, Viton and Buna-nitrile.
One thing I saw on viton somewhere else though and I have physically encountered the problem myself is that there seems to be many types of vitons and the differences in their quality in certain conditions are very drastic. I guess you will have to also know "what type of viton." :confused2:
http://www.pumprite.com/chemre.pdf
according to that chart Buna N and Viton are both excellent with natural hydraulic oil but Buna N is not very good with synthetic hydraulic oil and Viton is. I would also expect that Viton would be much better than Buna N with heat because Viton is like a rubberized teflon. That chart is likely "resistance at room temperature."
That chart of course does not include the strength, elasticity etc. and it could end up being that if the chemical resistance was all that was known that Buna N could actually end up being better for certain hydraulic parts even though you would not think so by that. For example the natural rubber they use for gas pumps and hydraulic hoses has been the best hose for very hot solvents Ive ever used but if you made a tiny o ring out of it it would break apart easier than cheap orings.
Regardless of all that it would nice if someone came along who has actually tried both on tractor hydraulic.
One thing I saw on viton somewhere else though and I have physically encountered the problem myself is that there seems to be many types of vitons and the differences in their quality in certain conditions are very drastic. I guess you will have to also know "what type of viton." :confused2:
http://www.pumprite.com/chemre.pdf
according to that chart Buna N and Viton are both excellent with natural hydraulic oil but Buna N is not very good with synthetic hydraulic oil and Viton is. I would also expect that Viton would be much better than Buna N with heat because Viton is like a rubberized teflon. That chart is likely "resistance at room temperature."
That chart of course does not include the strength, elasticity etc. and it could end up being that if the chemical resistance was all that was known that Buna N could actually end up being better for certain hydraulic parts even though you would not think so by that. For example the natural rubber they use for gas pumps and hydraulic hoses has been the best hose for very hot solvents Ive ever used but if you made a tiny o ring out of it it would break apart easier than cheap orings.
Regardless of all that it would nice if someone came along who has actually tried both on tractor hydraulic.
Last edited:
OP
Zebrafive
Super Member
Viton is 3-4 times more in price.
crazyal
Super Member
I'm use to dealing with much higher quality (and priced) seals like Chemraz and Kalrez but prices for Viton and Buna-N are about the same. Here's a site to one of the companies who supply us. It includes prices if you buy bulk. I think you'll be amazed just how cheap Viton and Buna-N are.
O-Ring Online Ordering
moship
Veteran Member
Below is a link to Parker's O-Ring Handbook that has everything you ever wanted to know about o-ring design and in Chapter 7 there is a chemical compatibility chart.
http://www.parker.com/literature/ORD%205700%20Parker_O-Ring_Handbook.pdf
As posted above, o-rings are prices differ significantly between sources. Besides the link mention above local industiral supply houses sell in bulk packages (10 to 25 pieces) at a fraction of the piece-cost for a single o-ring at a hardware, big box or tractor dealer.
http://www.parker.com/literature/ORD%205700%20Parker_O-Ring_Handbook.pdf
As posted above, o-rings are prices differ significantly between sources. Besides the link mention above local industiral supply houses sell in bulk packages (10 to 25 pieces) at a fraction of the piece-cost for a single o-ring at a hardware, big box or tractor dealer.
Wayne County Hose
Veteran Member
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- Massey Ferguson model 85, Allis-Chalmers WD-45
I have never had an issue with a properly installed Buna-n, or nitrile, o-ring. I would say rather than spend money on something you don't need take time and educate yourself on o-ring use and application. Www.herculesbulldog.com. Hercules sells the proper kits for orfs, boss and tube, flange, whatever o-ring you may need.
OP
Zebrafive
Super Member
That is the reason for this post. To get educated on which will serve me better, Buna-N or Viton. Buying bulk will be less expensive than buying one or two at a time at the dealer. Compared to buying one at a time, Viton in bulk is still a bargain. Even at 3-4 times the price of Buna-N. But if there is no need for Viton over Buna-N that's what I'll buy.
dynasim
Platinum Member
One should use the manufacturers recommendation unless they have had a failure related to chemical attack, or they have changed oil types. While some would say Viton has "drop in replacement" physical properties, I have not found that to be true.
Chris
Chris