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D635-22 – Standard Test Method Technical Guide
ASTM D635-22 is a fire-test-response standard that describes a small-scale laboratory procedure for screening the burning characteristics of plastics. It is specifically developed for materials used in components of devices and appliances. The test measures the linear rate of burning or the extent and time of burning of specimens tested in a horizontal position.
📐 Specimen Geometry and Types
Specimens for this test are prepared as bars, either molded directly or cut from sheets, plates, or panels. The standard dimensions are:
| 🟦 Parameter | 📏 Specification |
|---|---|
| Length | 125 mm ± 5 mm |
| Width | 13.0 mm ± 0.5 mm |
| Thickness | 3.0 mm to 13.0 mm |
Specimens must be conditioned per Practice D618. For materials with thickness less than 3 mm, multiple layers may be used to achieve the required thickness.
📌 This test method is technically equivalent to IEC 60695-11-10, Test Method A.
⚙️ Test Procedure and Flame Application
The test uses a laboratory burner conforming to ASTM D5025 with a 20-mm (50-W) flame verified by Practice D5207. The flame is applied for 30 seconds to the free end of the specimen. The following parameters are recorded:
| ⚡ Parameter | 🎯 Specification |
|---|---|
| Flame Height | 20 mm |
| Flame Application Time | 30 seconds |
| Reference Marks | 25 mm and 100 mm from the ignition end |
The linear burning rate is calculated if the specimen ignites and burns to the 100 mm mark. If the flame extinguishes before that, the extent of burning (mm) and time of burning (s) are reported.
⚠️ Users must establish appropriate safety, health, and environmental practices. See Section 9.2 for specific hazards.
📊 Key Measured Properties
The primary measurements include:
- Linear burning rate (mm/min) for materials that burn to the 100 mm mark
- Extent of burning (mm) for self-extinguishing materials
- Time of burning (s) for self-extinguishing materials
Materials are classified per Appendix X1 for quality assurance. For additional guidance on materials that do not burn to the first mark, refer to Test Method D3801.
This test is intended as a preliminary screening and does not replace full-scale fire hazard assessment.
✅ The results provide a comparative measure of flammability for component materials in devices and appliances.
❓ Frequently Asked Questions
🔍 What is the purpose of ASTM D635-22?
It provides a small-scale screening procedure for comparing the relative burning rates or extent of burning of plastics in a horizontal position.
💡 How are specimens prepared?
Specimens are prepared as bars with dimensions of 125 mm x 13 mm x 3 to 13 mm thick, conditioned per Practice D618.