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Ul Heat Shrinkable Sleeves are widely recognized in industrial and commercial sectors for their exceptional electrical insulation, mechanical protection, and flame retardancy. Certified by Underwriters Laboratories (UL), these sleeves are designed to meet stringent international safety and performance standards, making them an essential component for secure cable management and electrical insulation.
What is a Ul Heat Shrinkable Sleeve?
A UL Heat Shrinkable Sleeve is a polymer-based tubing that shrinks when exposed to heat, creating a tight, secure covering around wires, cables, or components. Made from cross-linked materials such as polyolefin or PVC, the sleeve typically has a shrink ratio of 2:1 to 4:1, allowing it to conform precisely to complex shapes. UL certification—most commonly UL 224—ensures compliance with rigorous safety and performance criteria including flame resistance, dielectric strength, and long-term material stability.
Key Features of UL Heat Shrinkable Sleeves
1. Thermal Shrinkage Behavior
Shrink activation temperature: 90°C to 150°C
Full shrinkage time: 30 to 120 seconds
Shrink ratio: 50–75% radial shrinkage
Memory effect ensures precise fit on varying geometries
2. Electrical Insulation Properties
Dielectric strength: 15–30 kV/mm
Volume resistivity: >10¹⁴ Ω·cm
CTI rating (UL 746A): >600V, ideal for high-voltage applications
3. Mechanical Protection
Tensile strength: 10–25 MPa
Elongation at break: 200–500%
Abrasion resistance: <100 mg weight loss after 1,000 ASTM D3389 cycles
4. Chemical & Environmental Resistance
Excellent resistance to oils, acids (pH 2–12), and solvents
Swelling: <10% after 168-hour immersion
Operating temperature: -55°C to +135°C
5. Flame Retardancy
UL 224 VW-1 compliant
Self-extinguishing within 60 seconds
LOI (Limited Oxygen Index): >28%
Heat release rate: <65 kW/m², suitable for confined spaces
Application Scenarios
Electrical & Power Systems
Cable Joints: Offers sealed 360° insulation for medium voltage up to 35kV
Busbar Coating: Ensures dielectric isolation and corrosion resistance
Transformer Terminals: Withstands Class H environments (up to 180°C)
Automotive Industry
Wire Harnessing: Replaces bulky tapes with 3:1 Shrink Sleeves
Battery Module Insulation: Compliant with UL 1973 for EVs
Sensor Cables: Shields wiring from oil and high-temperature fluids
Industrial Applications
Hydraulic Hose Protection: Adds abrasion resistance and color coding
Robotic Arms: Survives up to 1 million flex cycles
Explosion-Proof Boxes: Maintains seal integrity under pressure
Aerospace & Aviation
EWIS Compliance: Meets FAA FAR 25.1709 wiring safety standards
Corrosion Barrier: Prevents metal interface deterioration in composites
Weight Optimization: Specific gravity of 1.2–1.4 g/cm³, lighter than metal sleeves
Maintenance & Installation Guide
Installation Tips
Surface Cleaning: Use isopropyl alcohol to ensure surface energy >50 dynes/cm
Correct Sizing: Sleeve diameter should be 20–30% larger than the target component
Heating Method: Apply heat at 100–150°C using even, circular motion
Cooling Protocol: Allow slow cooling at ≤10°C/min to avoid cracks
Operational Maintenance
Annual Inspection: Use 10× magnification to detect microcracks
Insulation Resistance: Test with 500V megohmmeter, must exceed 100 MΩ
Thermal Aging: Monitor for discoloration or embrittlement over time
Repair & Replacement
Minor Damage: Use sealant with at least 90% surface coverage
Severe Deformation: Replace the sleeve if shrinkage exceeds 5%
UL Recognition: Always use UL-recognized (RU) components for repairs
Storage Conditions
Temperature: Store at 15–30°C
Humidity: Keep between 40–60% RH
Shelf Life: Use within 2 years following FIFO (First-In, First-Out)
UV Protection: Avoid exposure above 50 kLy/year cumulative dose
Why Choose UL Heat Shrinkable Sleeves?
Fully certified for UL 224 flame retardancy and electrical safety
Reliable performance in automotive, aerospace, industrial, and electrical applications
Backed by technical data and international standards
Provides long-lasting protection and reduces maintenance costs
Whether you're insulating power cables, protecting automotive harnesses, or managing aerospace wiring, a UL Heat Shrinkable Sleeve offers the ultimate combination of performance, safety, and durability. Contact us today to learn more or request a quote for customized sizing and color options.
