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D2903-21 – Standard Test Method Technical Guide
📐 Scope, Classification, and Units
ASTM D2903 – 21 specifies the requirements for flexible, crosslinked chlorinated polyolefin heat-shrinkable tubing used for electrical insulating purposes. It is supplied in an expanded form and will shrink to the specified diameter when heated.
Values in this specification are regarded as standard in inch-pound units. SI values given in parentheses are mathematical conversions provided for information only and are not considered standard. Temperatures are described in degrees Celsius.
Note: This standard does not have a similar or equivalent IEC standard.
Classification System
The tubing is categorized by its operational thermal performance:
| 🟦 Type | 📐 Description |
|---|---|
| Type I | Normal operating temperature |
| Type II | Extended operating temperature |
⚙️ Materials, Manufacture, and Test Methods
The compound used in the manufacture of this heat-shrinkable tubing shall be based on chlorinated polyolefin. This specifically includes a polymer or polymer blend based on chlorinated polyolefin(s), chlorinated olefin copolymer(s), or chlorinated polybutadiene polymer(s).
Several standard test methods are referenced to govern performance:
- D2671 – Standard Test Methods for Heat-Shrinkable Tubing for Electrical Use.
- D412 – Test Methods for Vulcanized Rubber and Thermoplastic Elastomers—Tension.
- D8355 – Test Methods for Flammability of Electrical Insulating Materials Used for Sleeving or Tubing.
- D3636 – Practice for Sampling and Judging Quality of Solid Electrical Insulating Materials.
Fluid Resistance Testing: The tubing’s resistance to specific fluids is evaluated using the following military standard specifications.
| 🎯 Standard | ⚡ Fluid / Application |
|---|---|
| MIL-H-5606 | Petroleum Base Hydraulic Fluid |
| MIL-T-5624 | Turbine Fuel, Aviation (JP4, JP5) |
| MIL-L-7808 / MIL-L-23699 | Synthetic Base Aircraft Turbine Oils |
| MIL-A-8243 | Anti-Icing and De-Icing Defrosting Fluid |
| MIL-G-5572 | Aviation Fuel (Grades 100, 130) |
| SS-S-550 | Sodium Chloride (Salt Spray / Corrosion) |
📊 Key Terminology and Ordering Information
Terminology: Definitions pertaining to electrical insulation are found in Terminology D1711. Fire-related terminology adheres to Terminology E176. The term chlorinated polyolefin is specifically defined in this standard as the polymer base for the tubing.
Ordering Information: When ordering to this specification, the purchaser must state the required Type, Class, and Size of the tubing to ensure the correct material and dimensions are supplied.
International Standardization: This standard was developed in accordance with internationally recognized principles on standardization established by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
❓ Frequently Asked Questions
🔍 What is the primary application of ASTM D2903 tubing?
It is specifically designed for use as flexible crosslinked chlorinated polyolefin heat-shrinkable tubing intended for electrical insulating purposes.
💡 What distinguishes Type I from Type II tubing?
Type I is intended for a normal operating temperature range, while Type II is formulated for an extended operating temperature range, providing greater thermal endurance.
⚡ Which standards govern the general testing of this tubing?
The general testing methods for heat-shrinkable tubing are covered under ASTM D2671. Additional standards include D412 for tension and D8355 for flammability testing.
📌 Can this standard be used directly with metric units?
The standard values are stated in inch-pound units. SI unit equivalents are provided in parentheses for reference only and are not considered the standard unit of measure, except for temperatures described exclusively in degrees Celsius.