I’ve specified, commissioned, and troubleshot enough air systems to know tubing is rarely the headline—but it’s often the root cause of leaks, drift, and downtime. The wrong material kinks on a robot elbow, creeps under pressure in a control circuit, or turns brittle after a winter startup. Buyers feel this as replacement spend and unplanned labor; engineers see it as Cv loss, response lag, and safety margins eroded by micro-leaks at push-to-connects. My goal here is to help you pick a tubing material that fits your pressure, temperature, chemicals, routing, and lifecycle cost—so you don’t have to think about tubing again.
The main pneumatic tubing materials I evaluate are polyurethane (PU), nylon (PA), PTFE (Teflon), polyethylene (PE), and thermoplastic elastomer (TPE). PU wins for flexibility and dynamic routing, PA for high pressure and dimensional stability, PTFE for extreme chemical/high temperature, and PE/TPE for cost-effective, low-pressure service. Polyurethane outperforms nylon in cold weather and tight-bend, moving axes; PTFE is my pick when aggressive media or sustained temperatures above ~90–120°C are present. PE and TPE are viable for economical plant air drops and low-pressure circuits if temperature, abrasion, and UV limits are respected.
In the sections below, I’ll compare PU, PA, PTFE, PE, and TPE against the realities of industrial environments—pressure/temperature envelopes, bend radius under motion, chemical compatibility, sealing in push-to-connects, and long-run cost. I’ll also call out where ether-based PU matters, when to step up to stainless steel tube, and how to avoid leak growth under vibration by matching fittings to tubing hardness.
How do PU, PA, PTFE, PE, and TPE compare for my pressure and environment needs?
Quick engineering comparison
- PU (polyurethane): Most flexible; excellent abrasion; moderate pressure; great for dynamic motion and tight routing.
- PA (nylon 11/12): Highest pressure among plastics; low moisture uptake; stable dimensions; better for fixed runs and control accuracy.
- PTFE (Teflon): Chemically inert; wide temperature range; low friction; stiff and costly; best for aggressive media/high temp.
- PE (polyethylene): Economical; good chemical resistance; low to moderate pressure; good low-temperature elasticity.
- TPE (thermoplastic elastomer): Soft and flexible like rubber; lower pressure; good for manifolds, short jumpers, and low-cycle motion.
Typical capability ranges (guide values; verify vendor datasheets)
| Material | Flexibility/Bend Radius | Working Pressure (at ~23°C) | Temperature Range | Chemical Resistance | Notes/Trade-offs |
|---|---|---|---|---|---|
| PU (ether-based) | Tight (20–30 mm on 6 mm OD) | 8–14 bar (125–200 psi) | -40 to +70/80°C | Good vs oils/fuels; fair vs strong solvents | Best for dynamic axes; select ether-based for humid/wet lines |
| PA 11/12 (nylon) | Semi-rigid (40–60+ mm) | 11–35 bar (160–500 psi) | -40 to +90/100°C | Excellent broad resistance; low moisture uptake | High pressure, stable ID/OD for control accuracy |
| PTFE | Rigid (large radius; kink-prone) | 15–25 bar at ambient; derates fast with heat | -70 to +200/260°C | Near-universal | Premium cost; use where chemicals/heat demand it |
| PE (LD/MD/HD) | Flexible to semi-rigid | 6–14 bar (83–200 psi) | -73 to +60/70°C | Very good (varies by grade) | Lightweight, economical; lower abrasion resistance |
| TPE | Very flexible | 4–10 bar (60–150 psi) | -40 to +60/70°C | Good water/glycol; check oils/solvents | Soft durometer seals easily; watch for creep under clamp loads |
Notes:
- Black, UV-stabilized PE or PA is my default outdoors to combat embrittlement.
- For vibration-heavy applications, match push-to-connect collet and seal design to tube hardness—leak rates fall dramatically when the material and ferrule geometry are paired correctly.
Practical selection flow I use
1) Boundaries: Max pressure and min/max temperature (knock out under/over-rated materials).
2) Routing: Required bend radius and dynamic movement (favor PU/TPE for motion; PA/metal for fixed runs).
3) Media and environment: Oils, coolants, solvents, washdown, UV, ozone (PTFE or PA if aggressive; ether-based PU for humid).
4) Lifecycle cost: Replacement interval, labor, leak energy cost, downtime risk (nylon or stainless where failure has safety/production impact).
When does polyurethane outperform nylon in flexibility and cold weather?
Flexibility and dynamic motion
In my experience, PU wins any time the tube must:
- Snake through tight enclosures or cable carriers without kinking.
- Survive continuous bending on robot wrists, pick-and-place slides, or tool changers.
- Maintain flow with small bend radii where larger loops are impossible.
Ether-based PU in particular keeps elasticity after millions of cycles and resists abrasion from cable carrier links. Nylon’s higher modulus helps with straightness and dimensional stability, but that stiffness translates to larger bend radii and higher side-loads on fittings during motion—both increase leak risk over time.
Cold-weather performance
- PU maintains flexibility to roughly -40°C, so I can route tight bends in freezers, docks, or winter startups without cracking.
- Nylon can become noticeably stiffer in the cold; while PA 11/12 is serviceable below freezing, it demands larger bend radii and is more prone to stress-cracks at sharp clips.
- For humid, cold environments, I preferentially specify ether-based PU to avoid hydrolysis that can affect ester-based PU over time.
Where nylon still wins
If your circuit pressure regularly exceeds ~14–15 bar, or you need exceptional dimensional stability for precise timing in valve islands and air logic, nylon is the right move—just give yourself routing space and use strain reliefs to keep side loads off the fittings.
When should I specify PTFE/Teflon for chemicals or high temperatures in my process?
Triggers that move me to PTFE
- Aggressive chemicals: Strong solvents (ketones, aromatics), halogenated cleaners, caustics, or unknown cocktail exposures where compatibility is non-negotiable.
- High temperature: Sustained temps above ~90–120°C where PU/PA/PE creep or soften; PTFE comfortably handles up to 200–260°C depending on grade.
- Purity and friction: Low extractables for pharma/semiconductor; low surface energy for sticky media; very low coefficient of friction to reduce pressure drop on long microbore runs.
Engineering cautions
- Pressure derating: PTFE’s hoop strength falls with temperature—always apply vendor derating curves. At 200°C, allowable pressure can be a fraction of the room-temperature rating.
- Kink risk: PTFE’s rigidity means large bend radii; I often add spiral supports or specify convoluted PTFE for flexibility.
- Fittings: Use PTFE-compatible ferrules or dedicated push-to-connects designed for hard-wall tubing; over-gripping can craze the tube.
- Cost: Expect 3–5× PU cost. I reserve PTFE for lines where failure is unacceptable (chemical feed to valves, hot manifolds, high-purity instrumentation).
If heat/chemicals are severe and pressure is also high, I’ll step up to stainless steel tubing with compression fittings—especially for outdoor, long-run, or safety-critical lines.
Are polyethylene and TPE viable for cost-effective, low-pressure lines in my facility?
Short answer
Yes—with guardrails. I use PE and TPE for economical, low-to-moderate pressure drops and instrument takeoffs where abrasion is minimal and temperatures are modest.
Where PE works well
- General-purpose plant air branches and instrument lines at 6–10 bar.
- Low-temperature areas (PE stays elastic well below -50°C).
- Applications needing broad chemical resistance at low cost (water/glycol, many acids/bases).
- Outdoor drops: choose black, UV-stabilized PE.
Limitations: Lower abrasion resistance than PU/PA; avoid tight clamps and sharp edges. Temperature ceiling (~60–70°C) rules out hot equipment bays.
Where TPE shines
- Very flexible short jumpers on valve manifolds and small actuators.
- Low-pressure circuits in compact panels where easy assembly and soft sealing are priorities.
- Noise-sensitive equipment—TPE can dampen vibration better than harder plastics.
Limitations: Lower pressure ratings and higher creep under sustained stress; keep runs short, support well, and avoid high-cycle dynamic motion compared to PU.
Bonus: PVC and stainless steel—when to consider or avoid
- PVC: Economical and flexible, but I avoid it for continuous high-pressure or dynamic motion—fatigue life is poor and temperature window is narrow.
- Stainless steel tube: My go-to for high pressure/temperature, long outdoor runs, and safety-critical circuits. Pair with compression fittings; leak rates and maintenance fall dramatically.
Material–application decision table
| Application Scenario | Recommended Material(s) | Why |
|---|---|---|
| Robot wrist, tight carrier radius, -20°C winters | Ether-based PU | Tight bend radius, cold flexibility, abrasion resistance |
| 12–16 bar control circuits, precise timing | PA 11/12 nylon (semi-rigid) | High pressure, dimensional stability, low moisture uptake |
| Caustic washdown + 120–180°C proximity | PTFE (or stainless steel) | Chemical inertness, high temp tolerance |
| Low-cost plant air drops in warehouse | Black UV-stabilized PE | Economical, UV resistant, good chemical resistance |
| Compact manifold jumpers, quick service | TPE or soft PU | Easy routing, good sealing in push-to-connects |
Implementation tips that cut leaks and downtime
- Match tubing OD tolerance and hardness to fitting style. Push-to-connects seal best when the tube’s surface hardness and ovality meet the collet’s bite design—mixing soft TPE with hard-metal teeth can cause creep and weeping.
- Use ether-based PU around moisture. It resists hydrolysis better than ester-based variants, especially in humid or water-exposed environments.
- De-rate smartly: temperature, chemicals, and pulsation shrink pressure ratings. Follow vendor curves and add 25–50% design margin on dynamic lines.
- Anchor and strain-relieve near moving axes. Side-loads at fittings cause micro-movement and O-ring wear—90% of “mystery leaks” I find come from unsupported bends close to the connector.
- For outdoor runs, select black, UV-stabilized nylon or PE and consider stainless tube where mechanical abuse or safety risk exists.
Conclusion
If I boil it down: polyurethane is my default for dynamic, tight-routing pneumatics; nylon is my lever for high pressure and dimensional stability; PTFE is the specialist for heat and aggressive chemistry; polyethylene and TPE are cost-effective for low-pressure, benign environments when you respect their limits. Ether-based PU beats nylon for flexibility and cold-weather motion, while PTFE earns its keep when failure is not an option around chemicals or heat. Pair the right tubing with fittings designed for its hardness and you’ll see fewer leaks, steadier actuation, and lower lifecycle cost.
