Heat-Shrink Sleeves Selection Guide
Heat-shrink sleeves come in standard and gel-lined adhesive types; shrink ratio (2:1, 3:1), wall construction and operating temperature matter when choosing.
This guide explains what to look for when choosing products in the Heat-Shrink Sleeves category.
Types of heat-shrink sleeves
- Standard heat-shrink sleeves: thin-wall polyolefin sleeves. According to the recorded values they shrink at a 2:1 ratio, are self-extinguishing and operate between -55 °C and +125 °C. Models described as flat also belong to this group.
- Gel-lined adhesive sleeves: double-wall. As the outer wall shrinks, the inner layer melts and fills the gaps around the part, then bonds as it cools. The models here have a 3:1 ratio; for Isıso models the recorded wall thickness is clearly greater than that of the standard type.
- Busbar insulation sleeves: the Gwest GWBT series, listed within the standard group, are thick-wall sleeves recorded as brick red, 2.5:1 ratio and 36 kV; they are used to cover busbar surfaces.
For those who prefer to buy pre-cut pieces, ready-made sleeve sets are in a separate category.
How to read the size and shrink ratio
The size in the product name is the nominal diameter; before shrinking, the sleeve is slightly wider than this size (for a 10 mm nominal Isıso sleeve the inner diameter is 10.5 ± 0.5 mm). Exact values appear in the "before shrinking" and "after shrinking" lines of the products where they have been entered. The shrink ratio gives the diameter the sleeve will reach when it shrinks freely: a 12.7 mm sleeve with a 2:1 ratio shrinks to about 6.4 mm, and a 12 mm sleeve with a 3:1 ratio shrinks to 4 mm.
- Fractional sizes such as 4.8 mm, 6.4 mm, 9.5 mm, 12.7 mm, 19.1 mm and 25.4 mm are the millimeter equivalents of inch fractions: 9.5 mm is 3/8 inch, 12.7 mm is 1/2 inch, and 25.4 mm is 1 inch.
- In busbar sleeves, the notation "50/20 mm" means an inner diameter of 50 mm before shrinking and 20 mm after shrinking.
- In the names of gel-lined Woer sleeves, a second diameter is written with "ø" next to the first size. The product record does not define this value; confirm the shrunk diameter from the manufacturer's data.
As the sleeve shrinks, its wall becomes thicker: on the recorded Woer 12.7 mm sleeve, the wall goes from 0.30 mm to 0.60 mm. Its length also shortens somewhat, so leave an allowance when cutting the piece.
The difference between 2:1 and 3:1 shrink ratios
A standard sleeve with a 2:1 ratio is for parts whose diameter changes little along their length: a single conductor, the barrel of a cable lug, a straight splice sleeve. A sleeve with a 3:1 ratio covers a wider range of diameters; it is chosen where it must be slipped over a large part such as a connector and shrink down to a thin cable.
In this category, the products with a 3:1 ratio are also adhesive-lined. The choice therefore usually comes down to two questions: how large the diameter difference is, and whether the splice needs to be sealed against moisture.
Shrinking: heat source and temperature
Operating temperature and shrink temperature are separate values: the first is the range the sleeve withstands continuously after shrinking, the second is the temperature at which shrinking takes place. For Gwest busbar sleeves the minimum shrink temperature is recorded as 105 °C; for other products, take the value from the manufacturer's datasheet.
The sleeve is shrunk with a controlled hot air source such as a heat gun or an oven. Uncontrolled sources such as lighters and soldering irons can cause uneven shrinking, damage to the sleeve and insulation failure. On long pieces, starting the heating from the middle and working toward the ends prevents air from being trapped under the sleeve.
What the colors are used for
Yellow-green sleeves are used to mark the protective (earthing) conductor, and blue sleeves to mark the neutral conductor; these two color codes are defined in IEC 60445. Other colors are chosen according to the project's color plan for distinguishing phases and circuits. A transparent sleeve leaves the label or conductor color underneath visible.
Brands in this category
- Woer: standard 2:1 sleeve rolls (including models named "flat type" and "tube type") and gel-lined adhesive sleeves with a 3:1 ratio.
- Isıso: IDM series colored 2:1 sleeves, flat models with the FLAT code, and IDM-YPK adhesive-lined sleeves.
- Gwest: GWBT busbar insulation sleeves.
Ordering notes
The sales unit of Isıso standard sleeves and Gwest busbar sleeves is the meter. Woer colored sleeves are sold by the roll length stated in the product name, and some of the gel-lined Woer sleeves are sold as 1.22-meter lengths; Woer black standard sleeves, however, are listed by the meter even though the name mentions a roll. Some Woer sleeves are made to order, and for these products the lead time is confirmed on the order.
For power cable splices that require a resin-cast joint, resin cable splice kits are in a separate category.
Heat-shrink tubing shrink ratio and selection table
| Heat-Shrink Subtype | Shrink Ratio | Operating Temperature | Application Advantage | Product Group |
|---|---|---|---|---|
| Standard thin-wall heat-shrink | 2:1 | -55 °C … +125 °C | Panel wire termination insulation, lug barrel covering, and phase color coding | Standard Heat-Shrink Sleeves |
| Adhesive-lined dual-wall heat-shrink | 3:1 / 4:1 | -55 °C … +110 °C | Inner hot-melt adhesive seals out water, moisture, and corrosion on cable joints | Adhesive Heat-Shrink Sleeves |
Frequently asked questions
Which diameter should I choose for a heat-shrink sleeve?
Measure the thickest and thinnest diameters of the part to be covered. The sleeve's inner diameter before shrinking must be larger than the thickest point, and its fully shrunk diameter must be smaller than the thinnest point. For example, a 12.7 mm sleeve with a 2:1 ratio shrinks to about 6.4 mm and suits parts that fall between these two values. If the diameter difference is larger, a 3:1 type is needed.
Can a heat-shrink sleeve be shrunk with a lighter?
The method recommended by manufacturers is a controlled hot air source such as a heat gun or an oven. Uncontrolled sources such as lighters and soldering irons do not shrink the sleeve evenly; they can cause damage and insulation failure. The shrink temperature varies by product; for the Gwest busbar sleeves in this category, the minimum shrink temperature is recorded as 105 °C.
When is a gel-lined (adhesive) sleeve needed?
The adhesive-lined type is chosen for outdoor and vehicle applications where the splice or connection is exposed to moisture, water or dust. When heated, the inner layer melts and fills the gaps between the cable and the sleeve, then bonds as it cools. In the dry environment inside an enclosure, a single-wall standard sleeve is used for insulation and color marking. Verify the sealing level from the manufacturer's data.
What voltage and temperature can a heat-shrink sleeve withstand?
The values vary by product. According to the records in this category, the operating temperature of Woer and Isıso standard polyolefin sleeves is between -55 °C and +125 °C; Woer standard sleeves are recorded as 600 V, and Gwest GWBT busbar insulation sleeves as 36 kV. For products with no voltage value entered, confirm the information from the manufacturer's datasheet.
What is the yellow-green shrink sleeve used for?
According to IEC 60445, the green-yellow color combination is used only to identify the protective conductor. A yellow-green sleeve keeps this marking in place when covering the lug barrel or splice of an earthing conductor. Blue sleeves are used on the ends of the neutral conductor; for phase and control circuits, the color is chosen according to the project's color plan.