Teflon orings
- Thread starter Candiru
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Never came across them — nor imagined them in a reg application
But if I had to make a guess:
- higher o2 index —> less fuel for the fire
- better resistance to solvents/ chemicals -> longer life
- better electrical permeability (or the lack of; but I can’t imagine why in a reg)
- softer? If yes -> better seal
Add extra grains of salts; just guessing
But if I had to make a guess:
- higher o2 index —> less fuel for the fire
- better resistance to solvents/ chemicals -> longer life
- better electrical permeability (or the lack of; but I can’t imagine why in a reg)
- softer? If yes -> better seal
Add extra grains of salts; just guessing
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Did you get your ideas from the book of numerous rear mounted auxlliary bottle diving deaths
www.deep6gear.com
Go do some research and go try stretch some teflon
Service Manual
www.deep6gear.com
Go do some research and go try stretch some teflon
Of which form?
Teflon HP seats are tough as hell
Teflon plumbing tape is softer than wet paper
I truly can’t tell how a Teflon oring feels like (or what range of softness it can have)
Poseidon used Teflon gaskets for their Cyklon 300s (2980s), for decades, in lieu of most of the HP and LP o-rings in the first stages — and they lasted for years. I still have a few whose gaskets are over twenty years old and they all remain airtight.
We used them extensively with high-O2 mixes, back when nitrox was still considered voodoo gas . . .
We used them extensively with high-O2 mixes, back when nitrox was still considered voodoo gas . . .
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I admit before this thread I had no clue of their existence, but doing a basic google search:
They seem to be available at a wide range of durometer in gasket (square oring) and oring (circular profile) format — at least this supplier claims it
PTFE GASKET company | Wuxi Xiangjian Ptfe Product Co.,Ltd.
The PTFE GASKET is Filled material: Filled PTFE products has more outstanding performance by adding filler such as carbon, graphite, bronze, glassfiber, carbon fiber, MOS2, PEEK, PI, POB BaSO4,., PTFE GASKET company, Shop Now
www.ptfefep.com
O-Ring Beschichtungen mit Gleitlacken & Trockenschmierbeschichtung
Verbessern Sie die Lebenszeit und Performance Ihrer O-Ringe, durch Beschichtungen. Die Flexibilität wird hierbei nicht beeinträchtigt. Beschichtung in modernen Massenbeschichtungsverfahren mit auf Ihre Bedürfnisse abgestimmten Beschichtungen.
www.adelhelm.de
I can’t tell if I’m being pranked here or what
Tanks A Lot
Contributor
PTFE has great mechanical properties:
It is currently the best choice available with regards to oxygen compatibility, even leaving FKM in the dust by a wide margin. Its low coefficient of friction means that moving parts can work much more efficiently than they otherwise would with a comparable elastomer. However, the instant compression set and poor sealing capabilities make this material a non-starter for some parts.
To give a few examples, my go-to O-ring for sealing oxygen cylinders with a 3/4"-16 UNF inlet is a 3.6 mm x 19.0 mm PTFE O-ring, such as this. As I get oxygen cylinders only once a decade, I found that FKM O-rings, under certain circumstances, failed prematurely.
I had a discussion with the guys from Deep6 a while ago, as they use another clever alternative. They use an O-ring that has an FKM core encapsulated in a PTFE layer. They use this O-ring on the barrel of the seat. The incredibly low coefficient of friction of the outer layer of PTFE means that the seat will move effortlessly, which in turn improves the performance of the first stage compared to a standard NBR or FKM O-ring. This also negates the need for a back-up ring.
This approach has the downside of not being the cheapest, and unfortunately, manufacturers are limited in how small they can manufacture these FKM-PTFE encapsulated O-rings. Here’s me hoping that this approach will be refined in the future down to the size of O-rings such as 1.0 mm x 2.2 mm. If this were to happen, I can dream of a manufacturer choosing one of these PTFE-encapsulated O-rings for their poppet in a balanced second stage. The O-rings on a balanced second-stage barrel are one of the limiting factors with regards to performance, as NBR, EPDM, or FKM introduce friction.
- Auto-ignition temperature of >427°C
- A super low heat of combustion at just 4,200–7,100 J/g
- One of the lowest dynamic friction coefficients of all materials at just 0.01 to 0.04 (obviously heavily dependent on the coupled material)
- One of the lowest static friction coefficients of all materials at just 0.08 (obviously heavily dependent on the coupled material)
- A virtually unlimited shelf life. Elastomers such as NBR, EPDM, or FKM will have to be discarded after a few years or a decade on the shelf.
- Most elastomers used in SCUBA will swell ever so slightly over time, depending on the lubricants used. The reason is that they absorb moisture/lubricants over time. While this is of no interest to the user, the engineer must take this into account. PTFE does not swell at all.
- It is inert to almost all chemicals (hardly relevant for SCUBA).
- Awesome dielectric properties, with around 60 kV/mm (hardly relevant for SCUBA).
- It has a very high hardness rating of 55 Shore. While this sounds low on the surface, this is on the "D" hardness scale, compared to elastomers like NBR or FKM, which are classed on the "A" hardness scale. This high hardness of PTFE means that it is less effective at sealing things. The soft elastomers deform easily to seal parts, but the harder PTFE does a poorer job at this. Oftentimes, things that get sealed via a PTFE O-ring require precision machining.
- PTFE is a polymer that does not belong to the elastomers. This means that once it deforms under pressure, it will stay that way. Think of it like an ordinary O-ring suffering from extreme compression set, but PTFE suffers this compression set instantly.
- It costs an arm and a leg, at least compared to "ordinary" elastomers.
It is currently the best choice available with regards to oxygen compatibility, even leaving FKM in the dust by a wide margin. Its low coefficient of friction means that moving parts can work much more efficiently than they otherwise would with a comparable elastomer. However, the instant compression set and poor sealing capabilities make this material a non-starter for some parts.
To give a few examples, my go-to O-ring for sealing oxygen cylinders with a 3/4"-16 UNF inlet is a 3.6 mm x 19.0 mm PTFE O-ring, such as this. As I get oxygen cylinders only once a decade, I found that FKM O-rings, under certain circumstances, failed prematurely.
I had a discussion with the guys from Deep6 a while ago, as they use another clever alternative. They use an O-ring that has an FKM core encapsulated in a PTFE layer. They use this O-ring on the barrel of the seat. The incredibly low coefficient of friction of the outer layer of PTFE means that the seat will move effortlessly, which in turn improves the performance of the first stage compared to a standard NBR or FKM O-ring. This also negates the need for a back-up ring.
This approach has the downside of not being the cheapest, and unfortunately, manufacturers are limited in how small they can manufacture these FKM-PTFE encapsulated O-rings. Here’s me hoping that this approach will be refined in the future down to the size of O-rings such as 1.0 mm x 2.2 mm. If this were to happen, I can dream of a manufacturer choosing one of these PTFE-encapsulated O-rings for their poppet in a balanced second stage. The O-rings on a balanced second-stage barrel are one of the limiting factors with regards to performance, as NBR, EPDM, or FKM introduce friction.
Polytetrafluoroethylene (PTFE) is listed as one of the O-ring materials, better known as Teflon.
Oh that’s a brilliant custom o ring — is that something we can get (relatively) easy, let’s say I wanna replace fkm orings for non D6 regs?
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