The Application And Selection of Cold Shrink Tube

What is a cold shrink tube used for?

Cold Shrink Tube is a tubular product that shrinks by physical principles. Its main working principle is to use the natural expansion of steel wire. Cold shrink tube is pre-expanded on a removable support tube during the manufacturing process. When it is needed, just position the cold shrink tube on the cable or connection part to be protected, and then pull out the supporting tube. At this time, the cold shrink tube relies on its own radial pressure to tightly wrap around the cable or connection, thereby playing a waterproof, moisture-proof and sealing role. 

Compared with heat shrink tube, the main difference of cold shrink tube lies in its working principle and application materials. Heat shrink tube mainly adopts the principle of radiation expansion and shrinks by chemical reaction, while cold shrink tube is based on physical reaction. 

According to different materials, cold shrink tubes mainly include silicone rubber cold shrink tubes and EPDM cold shrink tubes.

Cold shrink tubing is mainly used in the following industries due to its excellent physical and chemical properties, such as high temperature resistance, cold resistance, good electrical insulation, aging resistance and shrinkage, etc.:

1. Power system: used for insulation protection of terminal heads and intermediate joints of medium and high voltage power cables; protect cables from environmental influences such as ultraviolet rays, moisture, oil pollution and chemical corrosion; also used for insulation protection of substations, transmission lines, distribution networks and motor connections.

2. Communication cables: used for protection of terminals and joints of optical fiber cables, protection of joints and connection parts of communication cables, and ensuring the stability of signal transmission.

3. Automobile industry: used for protection of automobile wiring harnesses, especially in high temperature areas such as engine compartments; protection of cable connections of automobile batteries.

4. Shipbuilding and offshore photovoltaic industry: due to its good salt spray resistance and corrosion resistance, it is used for protection of cable joints in marine environments.

In order to ensure the reliability and safety of the cable system, how to choose the right type of cold shrink tube?

The first step in selecting cold shrink tubes is to measure the outer diameter of the cable and the length of the cable segment to be protected. The inner diameter of the appropriate cold shrink tube should be large enough to easily fit into the cable and provide a tight coating after shrinking. If the inner diameter of the cold shrink tube is too large, it may not be tight enough after shrinking, affecting the protection effect.

Secondly, the rated voltage of the cold shrink tube must be higher than or equal to the rated voltage of the cable. For example, for a 10kv cable, a cold shrink tube that can withstand at least 10kv voltage should be selected. This ensures that the cold shrink tube can still provide good insulation protection when the voltage fluctuates.

It is also necessary to select cold shrink tubes of corresponding materials according to the environment in which the cable is located, such as outdoor, humid, high temperature, chemical corrosion, etc. Cold shrink tubes made of silicone rubber are suitable for a variety of harsh environments, while materials such as EPDM have specific weather resistance and chemical corrosion resistance.

Another point is that the shrinkage ratio of the cold shrink tube is to ensure that it can provide sufficient radial pressure to achieve good sealing and insulation effects. The higher the shrinkage ratio, the tighter the cold shrink tube wraps around the cable after shrinking.