Choose the wrong air tubing and you find out the hard way — cracking in the sun, kinking on a moving axis, or sweating oil onto your products. Polyurethane (PU) and nylon (PA) are the two workhorses of pneumatic tubing, and they are not interchangeable.
PU tubing: flexible and forgiving
PU tubing is the soft, springy option. It bends around tight corners, follows moving machine parts without fatigue, and shrugs off repeated flexing that would eventually crack a stiffer material. It also has excellent memory — kink it, straighten it, and it returns to round.
That flexibility makes PU the default for robotic arms, pick-and-place cells, and any line that moves. It is also slightly cheaper per metre than nylon in most sizes.
Nylon (PA) tubing: stiff and strong
Nylon is the structural option. It holds its shape under pressure, resists abrasion better, and stands up to harsher chemicals and higher temperatures (up to around 100°C continuous in many grades). Moisture absorption is low, which keeps dimensions stable in humid plant air.
Nylon is the right call for fixed routing — along frames, inside cabinets, through conduit — where the line is installed once and forgotten. The stiffness that makes it durable also means it kinks if you force a tight radius, so plan your bends.
Quick comparison table
Flexibility: PU wins, hands down.
Abrasion resistance: Nylon wins.
Temperature range: Nylon handles more heat; PU gets soft around 60-70°C.
Kink resistance under motion: PU wins.
Dimensional stability: Nylon wins.
Price: PU is usually a little cheaper per metre.
The rule of thumb
Moving line → PU. Fixed line → nylon. Hot or abrasive environment → nylon. Tight space with sharp bends → PU.
And one practical tip: whatever material you choose, cut it square with a proper tube cutter. A ragged cut guarantees a leak at the push-in fitting, no matter how good the fitting is.
RUICHEN PNEUMATIC supplies PU, nylon and PE tubing from 4mm to 16mm plus tube cutters. Browse air tubing or ask for cut-to-length pricing.
Once the material is settled, the next question is size. See our guide to air hose sizes and fitting codes for how tubing OD and hose ID are measured differently.