Quick Answer
Polypropylene balls float and cost a fraction of PTFE. PTFE handles chemistry and temperature that PP cannot approach. PP’s density of ~0.90 g/cm³ puts it below water, making it the default for float duty; solid PTFE at 2.14–2.20 g/cm³ sinks, which is why buoyant PTFE applications use hollow balls instead.
Head-to-Head
| Property | PTFE | Polypropylene (PP) |
|---|---|---|
| Density | 2.14–2.20 g/cm³ (sinks) | ~0.90 g/cm³ (floats) |
| Continuous service temperature | -200°C to +260°C | 0°C to ~+100°C |
| Low temperature limit | -200°C | Becomes brittle below ~0°C |
| Chemical resistance | Near-universal | Good to acids, alkalis, salts; poor to oxidisers and aromatic/chlorinated solvents |
| Coefficient of friction | 0.04–0.10 | 0.25–0.35 |
| Tensile strength | ~20–35 MPa | ~30–40 MPa |
| Water absorption | < 0.01% | < 0.02% |
| Relative cost | Highest of the two | Lowest cost polymer ball in common use |
Buoyancy — the Usual Deciding Factor
Most PP versus PTFE decisions come down to whether the ball needs to float. PP floats in water naturally and requires no special construction, which makes it the standard choice for tank float valves, level indicators, sight glasses and float switches in aqueous service.
Solid PTFE sinks. Where an application needs both buoyancy and PTFE’s chemical resistance — a float in hot acid, for instance — the answer is a hollow PTFE ball, made from two machined hemispheres joined by thermal fusion and chemical welding. That gives buoyancy while retaining full PTFE capability, at higher cost than either solid PTFE or PP.
Where PP Is the Right Choice
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Float and level duty in water or mild aqueous chemistry. The classic PP application.
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Water and effluent treatment. PP handles most treatment chemistry at ambient temperature.
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Cost-sensitive high-volume use. PP is the cheapest common polymer ball by a clear margin.
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Dilute acid and alkali service below 100°C. Adequate, and specifying PTFE here is overspending.
Where PTFE Is the Right Choice
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Above about 100°C. PP softens and deforms; PTFE runs to 260°C.
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Below 0°C. PP embrittles and cracks; PTFE stays serviceable to -200°C.
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Strong oxidisers, aromatic or chlorinated solvents. These attack PP.
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Concentrated acids at temperature. PP’s resistance falls away as temperature rises.
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Very low friction requirements. PP’s friction coefficient is several times PTFE’s.
A Common Mistake
Specifying PP because it “handles chemicals” without checking temperature. PP’s chemical resistance data is usually quoted at ambient, and it degrades significantly as temperature rises — a PP ball that is fine in 30% sulphuric acid at 20°C may fail in the same acid at 70°C. If your service is warm and chemical, check both variables together rather than reading the chemical table alone.
We manufacture PP balls, solid PTFE balls and hollow PTFE balls, so tell us the media, the temperature and whether it needs to float, and we will recommend the one that fits rather than the one that costs most.
Related Reading
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PP Balls (/pp-ball) — product specifications
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PTFE Hollow Balls (/ptfe-hollow-ball) — buoyancy with full chemical resistance
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Engineering Plastic Balls (/engineering-plastic-balls)
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PTFE Material Properties (/ptfe-material-properties)
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PTFE Ball Selection Guide (/ptfe-ball-selection-guide)