Pneumatic Tubing: Material and Diameter Sizing

Which tubing material fits my application?

The material sets flexibility, chemical and temperature resistance. Polyurethane (PU) is kink-resistant, abrasion-proof and the first choice for most controls. Polyamide (PA) handles higher pressure and temperature and suits fixed piping. PE is cheap and light but less pressure-rated. For oil, coolant or hot zones always check the maker's media and temperature approval.

Outer or inner diameter which measure matters?

With push-in fittings, tubing is defined by its outer diameter (OD), typically 4, 6, 8 or 10 mm, because it must fit the valve's push-in port. The inner diameter (ID) instead sets the flow and therefore the piston speed. At 6 mm OD the ID is around 4 mm depending on wall thickness. For fast or large cylinders, step up one size.

• Check the valve's port size first, then choose the matching outer diameter.
• For fast cylinder strokes choose a larger inner diameter to avoid pressure loss.
• On long lines (over 2 to 3 m) step up one nominal size.

How do I check working pressure, temperature and routing?

Working pressure and temperature must be viewed together: the allowable pressure drops as temperature rises. Keep a safety reserve to the burst pressure and respect the minimum bend radius so the tube does not kink and throttle flow. Clean, short runs cut pressure loss and switching times.

Frequently asked questions