O-Rings... lots of O-Rings

[p6x]

 

[Scud]

That's a good chart. It would seem that most O-rings on motorcycles are Nitrile. But those green ones on the oil line fittings must be Highly Saturated Nitrile. And the seals in brake calipers and pistons must be Ethylene Propylene.

What kind of O-ring can seal a rabbit hole?

[80CX100]

On 2/2/2022 at 10:04 AM, Scud said:

Quite the education on O-rings. And I know that in high-reliability environments (mining, aviation, etc.), a mistake can be costly or deadly (Space Shuttle Challenger explosion).

A few years ago, I went down the rabbit hole of trying to find durable O rings to seal the cross over on the Lafranconi exhaust on my CX (which is the most idiotic design ever, jmho)

In my search, I spoke with the parts buyer at my local Freco Hydraulic shop, she advised me that since the space shuttle failure, O rings can be purchased made out of all sorts of miracle materials, money not being a consideration, she could get O rings that retailed for $600 Canadian a piece, I went with Vitons, iirc $10 @ dozen.

fwiw

[p6x]

1 hour ago, Scud said:

That's a good chart. It would seem that most O-rings on motorcycles are Nitrile. But those green ones on the oil line fittings must be Highly Saturated Nitrile. And the seals in brake calipers and pistons must be Ethylene Propylene.

What kind of O-ring can seal a rabbit hole?

I can bring more material and knowledge to the topic; as said before, o'rings have always been at the core of the many failures we had to contend with.

The oilfield environment always was a nice playing ground given the slue of effluents and conditions the o'rings had to be submitted to. This is one of the reason my company worked with chemical companies to get the best compound to address said conditions.

But for our purpose, Nitrile should suffice to cover the vast majority of our application. The fluid used in brake lines may be incompatible with Nitrile. The color of certain o'rings may be added for compound identification..

[p6x]

1 hour ago, 80CX100 said:

A few years ago, I went down the rabbit hole of trying to find durable O rings to seal the cross over on the Lafranconi exhaust on my CX (which is the most idiotic design ever, jmho)

In my search, I spoke with the parts buyer at my local Freco Hydraulic shop, she advised me that since the space shuttle failure, O rings can be purchased made out of all sorts of miracle materials, money not being a consideration, she could get O rings that retailed for $600 Canadian a piece, I went with Vitons, iirc $10 @ dozen.

fwiw

What is the maximum temperature the exhaust cross over experiences? The most resistant compound to temperature is Kalrez.

[80CX100]

19 minutes ago, p6x said:

What is the maximum temperature the exhaust cross over experiences? The most resistant compound to temperature is Kalrez.

Idk what the temps would be. It's a lower crossover under the sump so not crazy hot, but obviously hot enough to ensure failure of the O rings.

Anything that seems to be easily obtainable, evaporates and disappears in a very short time.

I'll be filing all this info away and will definitely keep that Kalrez material in mind.

Tks very much

[p6x]

@80CX100

Here's a table that can be used; for your application the fluid should be CO2 Gas; Viton is your best choice. You have to keep in mind that "cycling" ages your o'ring. Not that Kalrez is not good for low temperatures. I am not factoring pressure and differential pressure either.

 

[Lucky Phil]

7 hours ago, Scud said:

That's a good chart. It would seem that most O-rings on motorcycles are Nitrile. But those green ones on the oil line fittings must be Highly Saturated Nitrile. And the seals in brake calipers and pistons must be Ethylene Propylene.

What kind of O-ring can seal a rabbit hole?

Good question. I've dealt with orings of various types and materials all my life in aviation and motorcycles and cars. We had at one point issues with leading edge actuators leaking hydraulic fluid on long flights but were fine on shorter flights of sub3 hours. Of course when they did leak in cruise on the longer flights by the time the aircraft got on the ground the leak had disappeared. So long cruise and we had passengers taking images through the cabin windows of hydraulic oil coming off the trailing off the wing and when the aircraft arrived at the next port zero leaks. Quite frustrating to deal with from a certification perspective. The reason? Well the manufacturer had decided to change the actuator oring material to "something better" problem was the "something better" wasn't actually that great at -45 deg C 42,000' foot cruise for more than a few hours. Cold soak set in and so did the leaks. Long descant to warmer air for landing and the problem disappeared.

With regards to motorcycles the applications are pretty straight forward and as is the case in situations like this when all the technical intricacies and materials start to get delved into by people I simply go back to what has actually worked in previous practice. Theory and intricate detail on form function and material has it's place of course but apart from the transition to FKM/Viton for engines from Nitrile everything else seems to work acceptably well. The one interesting exception that needs to be considered on modern engines though that catches many mechanics esp home mechanics out is the use now of Flurosilicon seals for cranks and some other areas. Lubricating these when installing actually causes them to leak. They rely on being installed dry and the first rotations of the shaft deposits material from the seal onto the shaft and creates the sealing effect. If you don't read the manual and aren't aware you can have a major job on your hands to do the seal replacement all over again.

Ciao       

   

[Lucky Phil]

5 hours ago, p6x said:

@80CX100

Here's a table that can be used; for your application the fluid should be CO2 Gas; Viton is your best choice. You have to keep in mind that "cycling" ages your o'ring. Not that Kalrez is not good for low temperatures. I am not factoring pressure and differential pressure either.

 

You need to look at these charts with a careful eye. I've spent hours and hours researching these in the past and they very often contradict themselves or aren't comprehensive or detailed enough. This chart for instance look like it's geared more to the mining industry than the automotive and therefor I personally wouldn't rely on it entirely for motorcycle work. Not saying it's wrong but if you look at enough of them you start to get an idea of where their focus is and it makes a difference.I don't see Gasoline on this one and it's important not to extrapolate general stuff into specifics such as Hydrocarbon or tolulene into gasoline. I've seen these charts  indicate that Nitrile is fine in Gasoline which it is for a trapped seal but not as a dynamic seal and some Nitrile is better in fuel than other compounds. Even constrained nitrile seals when removed have swelled in gasoline and cant be reused so you need to not rely on any one particular of these generic charts as they can and do vary quite a bit.

Ciao   

[p6x]

5 minutes ago, Lucky Phil said:

You need to look at these charts with a careful eye. I've spent hours and hours researching these in the past and they very often contradict themselves or aren't comprehensive or detailed enough. I don't see Gasoline on this one and it's important not to extrapolate general stuff into specifics such as Hydrocarbon or tolulene into gasoline. I've seen these charts  indicate that Nitrile is fine in Gasoline which it is for a trapped seal but not as a dynamic seal and some Nitrile is better in fuel than other compounds. Even constrained nitrile seals when removed have swelled in gasoline and cant be reused so you need to not rely on any one particular of these generic charts as they can and do vary quite a bit.

Ciao   

This is for oil as in petroleum application only. There aren't any refined product in that chart.

All the fluids are either effluent coming from a well, or fluids used to drill or control the wells.

However, since we operate in the upper boundaries of the envelope, you can safely assume it should be fine for a V11.

[Lucky Phil]

Just now, p6x said:

This is for oil as in petroleum application only. There aren't any refined product in that chart.

All the fluids are either effluent coming from a well, or fluids used to drill or control the wells.

However, since we operate in the upper boundaries of the envelope, you can safely assume it should be fine for a V11.

I personally wouldn't assume that.

Ciao