Heat shrinkable tubing with a retraction rate of 3:1

What shrink ratio 3:1 Means ?

The desired characteristic of a heat shrinkable tubing is its ability to shrink in diameter under the effect of heat. Thus, heat shrinkable tubing with an initial internal diameter of 39 mm and a shrink ratio of 3:1, will see its diameter to the minimum restrained take the value of 13 mm.

More shrink ratio is important, i.e. greater than 2:1, the more the choice must be motivated by the need to restrain the tubing with distant diameters, including shrink ratio (the largest diameter divided by the smallest diameter) is greater than 2.

To complete this feature of tightened 3:1, manufacturers of tubing thermo-retrenchable sheaths are available with complementary tightness ratios such as the Restricted 1.2:1, Restricted 1.5:1, Restricted 2:1, Restricted 4:1 for fine walls, Restricted 6:1 for thick-walled sheaths with strong tight adhesive.

Example of a tubing with a shrink ratio of 3:1 : the dual wall tubing ratio 3:1 with adhesive model PF3-A

The heat shrinkable tubing PF3-A is a tubing With a round section in polyolethin cross-linked with EVA co-extruded adhesive, designed to ensure both insulation and sealing. Sound shrink ratio 3:1 allows to cover large diameter deviations while ensuring homogeneous clamping and excellent mechanical hold thanks to the internal resin. Waterproof after retraction, it operates from -55 °C to +135 °C, with complete retraction from 110 °C (beginning at 70 °C). Equipped with 20 kV/mm dielectric rigidity, flame retardant and VW-1 class (self-extinguishing except transparent version), it meets MIL-SPEC SAE-AMS-DTL-23053/5 classes 1 and 2. UV-resistant (excluding transparent), RoHS-compliant and REACH-compliant, it has a matt appearance, without marking, with very good flexibility and controlled longitudinal reduction (-15 % to +1 %).

In the case of a main beam coming out of an outer box, the thin-wall heat shrink tubing double adhesive in ratio 3:1 Ø39 mm is positioned before the final connection, then retracted to descend to about 13 mm. This high reduction rate allows to encompass both the main cable and the connection area (brush or splice), even in the presence of a larger connector. During heating, the polyoleumthin contract while the co-extruded adhesive melts and fills the gaps, creating a barrier Waterproof against moisture, dust and projections. After cooling, the assembly forms a sleeve mechanically reinforced, which secures the connection while ensuring reliable and durable electrical insulation.

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  • UV-resistant: yes