Calibrated Polyurethane Tube Medifly PU46 Yellow (Ø 4×6 mm, 98 ShA, Yellow)

1. Purpose and Operating Principle

The bright yellow color provides excellent visual identification of the compressed air line in multi-circuit distribution panels and process equipment. Made from elastic thermoplastic polyurethane with a hardness of 98 ShA / 52 ShD, the tube combines a high tensile strength margin with excellent flexibility and abrasion resistance. The calibrated 6 mm outer diameter guarantees 100% leak-tightness when fitted into quick-connect push-in fittings.

2. Technical Specifications

⚠️ Unconfirmed data / check with the manager before publishing:

• Exact weight of the 100 m coil (estimated ~1.98 kg, needs confirmation at shipping).
• Availability of the compact Fast Fly Box dispenser (10×10 m) in yellow.

3. Design Features

Decoding the Medifly PU46 Yellow part number:

Key design solutions:

• Outer wall calibration — a strict outer diameter tolerance (6.0 mm ±0.1 mm per ISO/TS 11619:2014) prevents air leaks and the tube pulling out of the push-in fitting’s collet under pressure pulsation.
• Bend resistance and memory effect — the polyurethane recovers its shape after crushing or kinking, withstanding repeated operating cycles in cable chains and flexible automation loops.
• Signal color identification — the yellow color is useful for grouping process lines (for example, a compressed air supply line at a specific pressure, or for a specific robot module).

4. Installation Recommendations

1. End preparation. Cut the tube strictly at a 90° angle, using only a dedicated guillotine-style tube cutter (plastic tube knife). An uneven cut made with pliers or scissors damages the fitting’s O-ring and causes leaks.
2. Fitting types:
   • Quick-connect push-in fittings with a 6 mm fitting diameter.
   • Compression fittings with a union nut and a 4×6 mm stem.
3. Bend radius. Maintain a minimum bend radius of at least 15 mm. A smaller radius can kink the bore and reduce air flow.
4. Pressure derating by temperature. As the working medium’s temperature rises, reduce the maximum working pressure per the coefficient (at +40°C — 7 bar, at +60°C — 5.2 bar).

5. Alternatives and Comparison

Cross-references (check diameters before substituting):

Comparison within the Medifly line:

• PU46 (98 ShA polyurethane) — high elasticity, flexibility, 10 bar working pressure, abrasion and bend resistance.
• PA46 (Polyamide / Nylon PA12) — rigid material, working pressure up to 25 bar, but a significantly larger bend radius (40 mm), harder to bend.
• PE46 (LDPE polyethylene) — chemically inert material for food and water applications, but inferior to polyurethane in flexibility and wear resistance.

6. Common Mistakes

• Cutting with an ordinary knife or pliers — crushes the 6 mm wall, so the fitting’s collet no longer grips the tube tightly.
• Use in systems with hot water above +60°C — exceeding the working temperature softens the polyurethane and causes it to rupture.
• Exceeding the allowable bend radius (<15 mm) — kinks the wall and reduces pneumatic actuator performance.
• Mounting on a barbed stem without a clamp — push-in or compression nut fittings are recommended for 98 ShA polyurethane.

7. Applications

• Pneumatic automation systems — connecting cylinders, valves, and pneumatic islands.
• Robotics and flexible cable chains — moving modules with a high bending frequency.
• Pneumatic tools and service lines — air supply on assembly lines and at auto service stations.
• Automotive and special-purpose vehicles — auxiliary pneumatic control circuits.
• Labeled pneumatic panels — visual color-coded separation of flows and control lines.

8. Expert Opinion

Vitalii Boluchevski, lead engineer at Acvatron SRL (18 years of experience): “The Medifly PU46 tube in yellow is one of the most commonly used standards for assembling pneumatic cabinets and automated lines. The 6×4 mm diameter provides excellent actuation speed for medium-sized pneumatic cylinders, and the bright yellow color significantly simplifies tracing and troubleshooting in complex multi-circuit systems. The Italian calibration guarantees secure retention in push-in fittings without leaking.”

9. FAQ

1. Does the PU46 Yellow tube fit Festo and Camozzi push-in fittings? Yes, the precise 6.0 mm outer diameter with ISO/TS 11619 tolerance ensures full compatibility with push-in fittings from all leading brands.

2. What’s the difference between polyurethane and polyamide (nylon) 6×4 mm? Polyurethane is significantly more flexible, doesn’t stiffen at low temperatures (down to −40°C), and has a smaller minimum bend radius (15 mm vs. 40 mm for polyamide). Polyamide is chosen where a higher working pressure is required (up to 25 bar).

3. Can this tube be used for compressed air with oil mist lubrication? Yes, polyurethane is resistant to mineral oils, lubricants, and non-aggressive petroleum products.

4. What coil sizes is the tube supplied in? The standard supply form is a 100-meter coil. Cut-to-length options in meter increments, or supply in Fast Fly cardboard dispensers, are also available.