Shrink Tubing Information
Shrink tubing conforms to the size and shape of wires, connections, open coils, and other electrically conductive elements to insulate and protect them from adverse environmental conditions. Heat shrink tubing, when heated, it shrinks to conform to the size and shape of the underlying material. This material can also be used to hold a group of wires together or offer sealing protection. Cold shrink tubing is a rubber sleeve that has been pre-stretched onto a removable core. When the core is removed the sleeve collapses down against the wire or cable. The tubing often comes in a wide range of sizes, colors, and materials.
There are two types of shrink tubing, thin or single wall, and dual or double wall.
Single wall shrink tubing provides superior insulation, strain relief, and protection against mechanical damage and abrasion. It provides reliable consistent dimensions and physical properties.
Double wall shrink tubing is best used when corrosion protection and sealing are required. An additional adhesive liner within tubing provides an additional seal against intrusion. This creates a moisture- resistant protective barrier that allows for a controlled amount of adhesive and consistent results.
Shrink tubing can also be purchased as an assortment pack with a variety of different sizes and colors in one kit. The shrink caps can be purchased individually. These pieces are used to seal off the end of a wire or cap.
Shrink cap. Image Credit: AlphaWire
Shrink tubing accessories are made from a variety of materials depending on the specific application. There is a multitude of varieties and chemical makeups available. The type of material and specific chemical makeup should be selected based upon the application to ensure there is no dangerous reaction or failures due to the environment. The following list describes common materials of construction.
Polyester is made from synthesized polymers. It can be used in a variety of applications since it is easy to wash and holds form well. However, care should be taken when using the material because it is highly flammable.
Polyolefin is a resin that exhibits resistance to chemicals and suitability for a wide range of media.
Polytetrafluoroethylene (PTFE) - Teflon® is an insoluble compound that exhibits a high degree of chemical resistance and a low coefficient of friction.
Polyvinyl Chloride (PVC) is a widely used material that has good flexibility, smooth surface properties, and nontoxic qualities. Some grades are used in food and chemical processes due to the inert nature of PVC. Brand names include: ACP® and Dural® (Alpha Gary), Geon® (Geon), Benvic® (Solvay), Flexalloy® (Teknor Apex).
Important performance specifications to take into consideration when searching for shrink tubing include the maximum diameter and the temperature range.
Heat shrink tubing. Image Credit: Cable Organizer
The maximum diameter for heat shrink tubing is the diameter of the bundle of wires and cables. The final shrink diameter of the tubing should be smaller than the object that the tubing will shrink around. This way the tube will shrink around the object tightly.
The length describes the overall length of the shrink tubing. A long roll of tubing can often be cut to a specified length for a desired application.
The temperature range is the full-required range of ambient operating temperature.
The shrink temperature is the temperature at which the material begins to conform.
The shrink ratio is a rating system which compares the difference in expansion and recovery rate. Although a ratio higher than what is needed should not be selected, a high shrink ratio will allow the sleeve to fit over larger objects
Flame retardant- Flame retardant products are designed to stop fire from affecting the contained material.
Thermal shield- A thermal shield is designed to stand high levels of heat.
EMI/ RFI shielding- This shielding provides protection against electromagnetic interference (EMI) and/or radio frequency interference (RFI)
Shrinkable products can be found in all major markets, such as the automotive industries, electronics industries, power stations, cable and wire industries, appliances, audio and video, power distribution, shipbuilding, communications, and telecommunications, off-shore industry, spacecraft, military industry, aviation industry, do-it-yourself stores, medical industries, rail and rapid transit, building and construction and many other markets. Typical applications for shrink tubing can be found in the field of insulating, terminating, splicing, cable bundling, color coding, strain relief, wire marking, mechanical protection, environmental protection, corrosion protection, and moisture sealing. Heat shrink tubing can be used instead of standard approaches to insulation, such as taping or molding.
Heat shrink tubing in use. Image Credit: Eric Arnold
Common approvals held by shrink tubing include CSA Mark (US, C and US, NRTL/C), UL Listing Mark, and UL Recognized Component Mark (US and Canadian). The CSA Mark may appear alone or with indicators. If it appears alone, it means that the product is certified for the Canadian market, to the applicable Canadian standards. If this Mark appears with the indicator "C and US" or "NRTL/C" it means that the product is certified for both the U.S. and Canadian markets, to the applicable U.S. and Canadian standards. The UL Listing Mark denotes that Underwriters Laboratories Inc. (UL) has found that samples of the product met UL's safety requirements.