While most common O-Ring supplies are rubber or elastomeric compounds, sure working conditions and hardware configurations merit using PTFE because the material.
PTFE presents many distinct advantages over elastomers. These advantages embrace corrosion resistance, huge temperature range capabilities, wonderful electrical properties and an nearly unlimited shelf life, to name a few.
But some considerations needs to be taken into consideration before making the switch to a PTFE O-Ring.
While PTFE affords some distinct advantages over elastomers, it additionally has some draw-backs that can negatively affect seal performance.
Eclipse provides absolutely custom-made PTFE O-Ring sizes out of our full range of PTFE blends that can help increase performance and longevity for your seals. But in some cases, an Eclipse Spring Energized seal may be your best option for optimal sealing performance.
Here’s easy methods to decide whether a PTFE O-Ring or Spring Energized seal is one of the best on your application.
Advantages of PTFE O-Rings
Chemical compatibly is commonly one of the first things checked when specifying an O-Ring material.
Media that isn’t compatible with typical rubber compounds, or caustic or corrosive chemical compounds can make PTFE the best choice of material.
PTFE is impervious to nearly all industrial chemical substances, making it one of the most corrosion resistant materials available throughout all industries. And it the integrity of rubber compounds is being compromised by chemical attack, then PTFE may do the trick.
Applications requiring lengthy-life or extended service intervals in corrosive environments may additionally merit the usage of PTFE.
While some elastomers would possibly survive for the quick time period or in intermittent exposure, degradation over time might lead to problems years down the road, whereas PTFE’s resistance properties will remain indefinitely.
Large temperature range capabilities
PTFE’s temperature range capability of -325°F to +500°F is also well beyond the range of most elastomers.
Applications in cryogenics or high temperature situations similar to ovens or combustion processes may rule out any elastomer compound, again making PTFE the best choice.
Extraordinarily low temperatures will cause most rubber compounds to harden to the purpose where any elastomeric properties are now not current within the material. This mixed with contraction of the material can imply it will no longer operate successfully as a seal.
PTFE, on the other hand, retains flexural and pliability properties even at cryogenic temperatures.
Additional Benefits to PTFE O-Rings
PTFE has some additional advantages over rubber compounds as well:
Unlimited Shelf Life: PTFE doesn’t degrade with age and is unaffected by UV light, so age management isn’t typically essential
PTFE doesn’t swell due to moisture absorption
PTFE will not be inclined to explosive decompression
Virgin PTFE is FDA Compliant
PTFE has excellent electrical properties reminiscent of dielectric strength and electrical resistance
The Disadvantages of PTFE O-Rings
While chemical attack or excessive temperature might not leave any choice besides PTFE, there are some disadvantages to the material that would have an effect on your project.
Virgin PTFE’s hardness is fifty five Shore D, which is much harder than a typical Nitrile O-Ring at 70 Shore A, which is a softer scale.
The higher hardness negatively affects sealability, as the material doesn’t conform the mating hardware surfaces as easily.
While rubber O-Rings might conform to “as machined” surfaces, PTFE may require publish-process surface finish improvements to control leakage to acceptable levels.
Generally, under regular conditions, the leakage rate for a PTFE O-Ring will be higher than any elastomeric compound.
The usage of a PTFE O-Ring isn’t advisable for applications that don’t require excessive temperature or extreme chemical conditions.
PTFE’s nature as an inelastic materials means that reuse or a number of installations of the identical seal will not be possible.
Unlike rubber compounds, PTFE will not return to it’s original shape and cross-section once deformed throughout set up and use. That means PTFE O-Rings are typically only really useful for static face seal or flange type configurations that aren’t actively engaged and disengaged.
For instance, a PTFE O-Ring wouldn’t be really helpful for a chamber door seal that must be opened and closed often, because the O-Ring would likely have to get replaced after every use.
A reused PTFE O-Ring may look and perform similarly to a typical rubber O-Ring affected by extreme compression set. But unlike rubber, this compression set happens after only one use.
More usually, PTFE O-Rings are present in flange gasket type applications where the seal will stay static and undisturbed until the subsequent service interval.
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