Quick Answer
PTFE, PFA and FEP have nearly identical chemical resistance and differ mainly in processing and temperature. PTFE cannot be melt-processed but has the highest service temperature (~260°C) and lowest cost. PFA is melt-processable, matches PTFE thermally, and resists permeation better — at significantly higher cost. FEP is melt-processable and transparent but limited to about 200°C. For solid balls, PTFE is almost always the correct choice.
Head-to-Head
| Property | PTFE | PFA | FEP |
|---|---|---|---|
| Continuous service temperature | ~260°C | ~260°C | ~200°C |
| Melt processable | No — compacted and sintered | Yes | Yes |
| Chemical resistance | Near-universal | Near-universal | Near-universal |
| Permeation resistance | Good | Best of the three | Good |
| Transparency | Opaque | Translucent | Transparent |
| Coefficient of friction | Lowest | Slightly higher | Slightly higher |
| Cold flow / creep | Highest | Lower than PTFE | Lower than PTFE |
| Relative cost | Lowest | Highest | Higher than PTFE |
What Actually Differs
Processing route
This is the fundamental distinction. PTFE has a melt viscosity so high that it cannot be injection molded or extruded conventionally — it must be compacted from powder and then sintered. PFA and FEP were developed specifically to be melt-processable, which makes them viable for tubing, film, linings and injection-molded parts where PTFE is impractical.
For a solid ball, this advantage disappears entirely. Compaction and sintering produce dense solid spheres economically at any diameter from 5 mm to 310 mm. There is no processing benefit to PFA or FEP in this geometry.
Temperature
PTFE and PFA are effectively equivalent at around 260°C continuous. FEP is the outlier, limited to about 200°C, which rules it out of a meaningful band of process duty that the other two handle.
Permeation
PFA has measurably lower permeability than PTFE. This matters in ultra-high-purity semiconductor chemical handling and in containment of aggressive gases, where trace permeation through a wall is unacceptable. For a check ball — which is a solid part in a flow path, not a containment barrier — permeation is not a design consideration.
Cold flow
PFA and FEP creep less than PTFE under sustained load. This is a genuine advantage, but for balls it is generally addressed more economically by moving to a filled PTFE grade, which reduces cold flow substantially at a fraction of PFA’s cost.
Why PTFE Is the Right Choice for Balls
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Cost. PTFE is significantly cheaper than both alternatives, and the ball geometry gives up none of PTFE’s advantages.
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Diameter range. The compaction-and-sinter route scales to 310 mm. Melt processing large solid spheres void-free is far harder.
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Highest temperature with lowest friction. PTFE leads on both.
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Established documentation. Virgin PTFE has the longest track record for food, pharmaceutical and potable water compliance.
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Cold flow has a cheaper fix. Filled PTFE addresses the one property where PFA genuinely leads.
When You Would Genuinely Specify PFA
There are real cases, and they are narrow: ultra-high-purity semiconductor chemical delivery where trace permeation or extractables must be minimised, and certain aggressive gas containment applications. If your specification came from a semiconductor fab or an ultra-pure chemical process, the PFA requirement is probably real. If it came from a general process engineering specification, it is worth asking whether PTFE was ever properly evaluated — the cost difference is substantial and the functional difference in a ball is usually nil.
Related Reading
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PTFE vs Teflon (/ptfe-vs-teflon) — brand name versus polymer
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PTFE Material Properties (/ptfe-material-properties)
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Filled PTFE Balls (/filled-ptfe-ball) — the economical answer to cold flow
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Virgin PTFE Balls (/virgin-ptfe-ball)
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PTFE Ball Selection Guide (/ptfe-ball-selection-guide)