VITON and high temperatures

[neseng]

It concerns me when reading various posts on this forum, just how many members are using, or considering using VITON 'O' rings in their projects.

I do not want to come across as an alarmist, but readers should be aware of some important facts regarding VITON.

If VITON®is used above 315°C the surface may contain hydrogen fluoride
condensate which may cause severe burns.

VITON 'O' rings and high temperatures are a BIG NO-NO! When viton is exposed to high temperatures, it degrades and one of the nasties produced is 'HYDROFLOURIC ACID' which is a deadly poison.

Aqueous hydrofluoric acid is a contact-poison with the potential for deep, initially painless burns and ensuing tissue death. By interfering with body calcium metabolism, the concentrated acid may also cause systemic toxicity and eventual cardiac arrest and fatality. (...and it only takes very small quantities to do the damage!)

I would NEVER even entertain the idea of using 'O' rings, especially Viton, in the applications many have suggested or in any application exposed to high temperatures on any engine.

If the Viton 'O' ring shows any signs of having a sticky, brown coating after use, DO NOT HANDLE IT with bare hands, remove it with a tool and dispose of it safely and then thoroughly wash the component that it was removed from.

For further information, just Google VITON MSDS or Hydroflouric Acid MSDS.

Work safe and stay alive,

Regards, Norman.

 

[Hopper]

Thanks. That's interesting. Triumph motorbikes of the 1970s used/use viton o rings to seal their pushrod tubes going into the cylinder head, so they would get pretty warm there. Will have to treat them with a bit more respect in future.

 

[aonemarine]

The real question is... whats the concentration? this thread is meaningless without knowing the concentration....

 

[jgedde]

It concerns me when reading various posts on this forum, just how many members are using, or considering using VITON 'O' rings in their projects.

I do not want to come across as an alarmist, but readers should be aware of some important facts regarding VITON.

If VITON®is used above 315°C the surface may contain hydrogen fluoride
condensate which may cause severe burns.

VITON 'O' rings and high temperatures are a BIG NO-NO! When viton is exposed to high temperatures, it degrades and one of the nasties produced is 'HYDROFLOURIC ACID' which is a deadly poison.

Aqueous hydrofluoric acid is a contact-poison with the potential for deep, initially painless burns and ensuing tissue death. By interfering with body calcium metabolism, the concentrated acid may also cause systemic toxicity and eventual cardiac arrest and fatality. (...and it only takes very small quantities to do the damage!)

I would NEVER even entertain the idea of using 'O' rings, especially Viton, in the applications many have suggested or in any application exposed to high temperatures on any engine.

If the Viton 'O' ring shows any signs of having a sticky, brown coating after use, DO NOT HANDLE IT with bare hands, remove it with a tool and dispose of it safely and then thoroughly wash the component that it was removed from.

For further information, just Google VITON MSDS or Hydroflouric Acid MSDS.

Work safe and stay alive,

Regards, Norman.

Good advice, but 315 deg C is HOT (600 deg F). If your cylinder walls and pistons are this hot in a model engine, you've got other issues besides safety to contend with: like why did the engine sieze up? Why has the lubrication turned into sticky black goo? Hey, where is that smoke coming from?

(The combustion flame will not get at the ring in any reasonable engine)

In any case, I would think we're talking about a few micrograms of HF in say a 1" diameter O-ring. That won't do much if any damage to the skin. You wouldn't even notice it.

I'm for safety as much as the next guy, but I'm starting to feel like I'm surrounded by fear-mongerers. This isn't meant as a flame, and I consider your input good advice if ever I work with significant quantities of Viton at high temperatures. But, a small O-ring? I'm skeptical to say the least. But, you did say you don't mean to be an alarmist...

Cheers!
John

 

[rcaffin]

It concerns me when reading various posts on this forum, just how many members are using, or considering using VITON 'O' rings in their projects.
If VITON®is used above 315°C the surface may contain hydrogen fluoride
condensate which may cause severe burns.

Ah, but what are the alternatives, and who uses O-rings at 300 C anyhow???
I suggest that talking about 315 C is simply not relevant to normal model engineering conditions.

Reality check: Viton is the standard material used by industry for temperatures up to (say) 200 C, which is well above what most any other common O-ring material can handle with the exception of Teflon. It handles normal fuels very well, and has a good life.

Cheers

 

[mu38&Bg#]

I have no doubt the dangers of hydrofluoric acid. The question really is how much acid is formed when an o-ring decomposes and whether or not the decomposition temperature is attainable. How hot does a 125cc gokart engine exhaust run?

What do these o-rings look like after a few races? Has anyone experienced the type of burns described above when changing them?

http://www.accelerationkarting.com/cr125o-ringexhaustmanifold.aspx

 

[neseng]

In my original post, I did say that VITON at elevated temperatures COULD be dangerous. In most applications that are mentioned by contributors above, I agree that it is probably quite safe and well below 315deg C. However, we have had members of this forum suggesting it's use as a valve seat material or as a gasket for a leaking or blown exhaust flange gasket. Both of these applications put the VITON in direct contact with flame.

Aqueous hydrofluoric acid is a contact-poison with the potential for deep, initially painless burns and ensuing tissue death. By interfering with body calcium metabolism, the concentrated acid may also cause systemic toxicity and eventual cardiac arrest and fatality. (...and it only takes very small quantities to do the damage!)

Notice that the acid burns are initially painless. I do not know the quantity required to do the damage, however inhalation exposure of 50 PPM for 5 minutes can be fatal so I imagine one drop or smear of hydroflouric acid off an over heated VITON 'O' ring is definitely to be avoided.

For reference, read the Toxological Informantion Section of: http://www.sciencelab.com/msds.php?msdsId=9924296

Finally, by all means use VITON 'O' rings but it does not hurt to know that there are concerns about it's use at elevated temperatures.

Norman.

 

[windy]

Some years ago the car repair trade were warned about the dangers of Viton O rings when a car had been in a fire.

Paul

 

[Generatorgus]

Yeah, and the sun is bad for ya too!!!

Almost everything we do is dangerous as of late.
My work is dangerous, some of my toys are dangerous, and I love to play with things that go bang.
Maybe we should all just hide under a rock, but I suppose ther would be danger involved there also.

Damn the toroedos, full speed ahead!!!

That's all I have to say about that.

GUS

 

[Tin Falcon]

the #1 safety tool we have is our brain. Use it. We can not afford to rush in where angels fear to tread or throw caution to the wind and throttle full speed ahead. staying and home and watching TV has its own risks and dangers.

I work at the place that makes Viton. There are tank cars of Hydrogen fluoride on site as well as lots of other nasty stuff that can kill you in six different ways if exposed this includes phosegene. I get regular safety training. and have to do all work with care.

My wife on the other hand works part time stocking greeting cards on store shelves. she goes to a local school play and trips on a parking barrier in a parking lot trips bruises her face ends up in the ER( two trips) and a half dozen stitches in her lip.

so be aware of all potential dangers , keep your head in the game , think, make wise choices , and get the job done SAFELY.
as far as as viton rings in egines as long as we keep our cool things should be fine if things get hot do not breathe the fumes.

Tin

 

[neseng]

Well, .....I rest my case! The facts are out there for anyone to research or to do their own investigations and come to their own conclusions.

I feel sorry for those that regard the safety and well being of their fellow men with such disdain!

But sad as it is, that is the world in which we live!

Norman.

 

[rcaffin]

In my original post, I did say that VITON at elevated temperatures COULD be dangerous. In most applications that are mentioned by contributors above, I agree that it is probably quite safe and well below 315deg C. However, we have had members of this forum suggesting it's use as a valve seat material or as a gasket for a leaking or blown exhaust flange gasket. Both of these applications put the VITON in direct contact with flame.

I totally agree that exposing Viton to an actual flame is stupid. Equally, putting it in contact with a near-glowing exhaust pipe would be equally stupid. No argument there. I imagine using it as valve seat material for a steam engine might work OK - but it's a poor choice for other reasons.

Aqueous hydrofluoric acid is a contact-poison with the potential for deep, initially painless burns and ensuing tissue death. By interfering with body calcium metabolism, the concentrated acid may also cause systemic toxicity and eventual cardiac arrest and fatality. (...and it only takes very small quantities to do the damage!)

Read the MSDS. This is a gross exaggeration. You would need to ingest quite a lot of HF to create this sort of damage, and one O-ring will not produce that. Blimey - it's not ricin!

I do not know the quantity required to do the damage, however inhalation exposure of 50 PPM for 5 minutes can be fatal so I imagine one drop or smear of hydroflouric acid off an over heated VITON 'O' ring is definitely to be avoided.

One drop of any concentrated acid is to be avoided, but that is way, way different from using an O-ring. You would need an awful LOT of HF to to produce an inhalation of 50 ppm for 5 minutes!

We all know that oxygen is vital to life. Did you know that 100% oxygen can be fatal to humans? True. Check it out.

Keep things in context.
Cheers

 

[Tin Falcon]

I feel sorry for those that regard the safety and well being of their fellow men with such disdain!

That in my option is a very judgmental statement. Are you trying to stir up arguments. That behavior is not allowed here.

I do not believe anyone here is really throwing caution to the wind .

Di hydrogen monoxide at elevated temperature will cause severe burns . large quantities can cause asphyxiation. lower the temperature and contact with it will cause tissue damage should we remove this substance from our homes and shops as well. ??
Back to viton O-rings. Every IC engine i have seen at shows you can put your hand on they barely get warm to the touch.

All here are entitled to there respectful opinion I will not allow this or any thread turn into a heated argument.
Tin

 

[jgedde]

Di hydrogen monoxide at elevated temperature will cause severe burns . large quantities can cause asphyxiation. lower the temperature and contact with it will cause tissue damage should we remove this substance from our homes and shops as well. ??
Tin

Good one Tin. I didn't catch it at first! Dihydrogen Monoxide... AKA H20

John

 

[enfieldbullet]

i must say i'm right there with the op with safety, i have been a chemophobe for some time.

the things that cured me were lab classes and chem accidents. i have inhaled and been burned by several acids and chemicals during the years, and it's not that bad. that includes ammounts of organic solvents that made me believe i must have hurt my liver (exams came out ok though)

my fear remains however over metallic salts and organic compounds, i loathe cromium and solvents. that stuff will acumulate in your system and kill you long after exposure.

i take acid over that any day.

which reminds me my blood lead level is a little high, which i think for the home machinist is a more reallistic threat. it is silent and cumulative and lead is far more present in machining.

my rules are get tested for heavy metals every year, use plenty of ventilation and know what you're handling(use proper safety equipment)

i must say i'm admired that the op took the time to read the MSDS, not many would do that. you should be proud about it.

but as a chemhead i must give you the advice to not get overly stressed about it, it's like reading the side-effects on any medicine.

*edit

i would also like to add that i'm not just a bonehead here, i have attended college as a biochemist (although i didn't graduate) and many of my teachers share the same philosophy.

 

[aonemarine]

im having a nice tall galss of it right now....
http://en.wikipedia.org/wiki/Hydrofluoric_acid

 

[Tin Falcon]

Maybe I need to buy one of these???

Tin

 

[aonemarine]

Maybe I need to buy one of these???

Tin

Only if you let it get cold.....LOL

 

[enfieldbullet]

the red is more of a flammability hazard.

i believe the health hazard(burns) would be the blue one.

i don't understand the reactivity 4 though

 

[Henry]

I think that is not the radioactivity is the biohazard symbol.
But I need a lot of that substance every day to keep moving.