ASTM D635-22 PDF

Full title and description

ASTM D635-22 — Standard Test Method for Rate of Burning and/or Extent and Time of Burning of Plastics in a Horizontal Position. This small-scale laboratory procedure measures and compares the linear rate of burning and the extent/time of burning of polymeric materials (bars, molded pieces, or cut specimens from sheets, plates, or panels) when tested in a horizontal orientation.

Abstract

This test method provides a repeatable screening procedure to determine the relative horizontal burning behavior of plastics under specified laboratory conditions. Results are intended for material comparison, quality control, and preliminary flammability assessment for components used in devices and appliances; correlation with real-world fire performance is not implied and further testing may be required. The method includes specimen preparation, ignition source and exposure conditions, measurement of burning rate or extent, and classification guidance.

General information

• Status: Active standard (current edition).
• Publication date: July 1, 2022 (issued as D635‑22; approval and publication in mid‑2022).
• Publisher: ASTM International.
• ICS / categories: 13.220.40 (Ignitability and burning behaviour of materials and products); 83.080.01 (Plastics in general).
• Edition / version: D635‑22 (2022 revision).
• Number of pages: 8 pages.

Scope

This method covers a small‑scale laboratory screening procedure to compare the relative linear rate of burning and/or extent and time of burning of plastics when tested in the horizontal position. It applies to bars and specimens molded or cut from sheets, plates, or panels. The standard is intended as a component‑level screening test (polymeric parts in devices and appliances) and includes classification guidance (see Appendix X1). The method is technically equivalent to IEC 60695‑11‑10 Test Method A for the same purpose; supplementary methods such as ASTM D3801 or D2863 may be used for additional flammability characterization.

Key topics and requirements

• Specimen geometry and conditioning: specimen dimensions, thickness control, and preconditioning to ensure comparable results across tests.
• Ignition source and exposure time: defined flame source, application duration, and test fixture orientation (horizontal).
• End points and measurements: determination of linear burning rate (typically reported as mm/min or mm/s), extent of burning (distance to reference marks), and time to extinguishment.
• Classification and reporting: optional classification system for quality assurance and material preselection (Appendix X1) and required test reporting elements (material description, thickness, conditioning, test results).
• Limitations and interpretation: results are valid only for the specific test conditions; material thickness, additives, pigments, and anisotropy affect outcomes and may require complementary tests.
• Safety considerations: precautions for operator exposure to combustion gases and safe laboratory practice during burning tests.

Typical use and users

Used by polymer manufacturers, materials laboratories, component and product designers, quality/acceptance testing labs, compliance engineers, and R&D groups to screen and compare horizontal burning behavior of plastic materials. The test is frequently used early in material selection, for production quality control, and as part of a suite of flammability tests when evaluating components for electrical/electronic devices and appliances.

Related standards

Standards commonly referenced alongside D635 include: IEC 60695‑11‑10 (Test Method A — technically equivalent horizontal burning test), ASTM D3801 (vertical burning of plastics, e.g., UL 94‑equivalent), ASTM D2863 (oxygen index), ASTM D648 (deflection temperature — relevant when specimens may relax), ASTM D4804 (thin sheet/film burning tests), and other ASTM fire‑test procedures for plastics and assemblies.

Keywords

burning rate, horizontal burning, plastics, flammability, linear rate of burning, extent of burning, time of burning, HB, small‑scale burning test, ASTM D635, D635‑22.

FAQ

Q: What is this standard?

A: ASTM D635‑22 is a standardized test method for measuring the rate of burning and/or extent and time of burning of plastics in a horizontal position. It provides a controlled, repeatable laboratory screening procedure for comparing materials.

Q: What does it cover?

A: It covers specimen preparation, test apparatus and orientation, ignition source and exposure, measurement of burn distance/time (linear burning rate), reporting requirements, and an optional classification scheme for quality assurance. It is intended as a component‑level screening test rather than a full product fire‑hazard assessment.

Q: Who typically uses it?

A: Material suppliers, R&D and quality labs, product designers, test houses, and compliance engineers use D635 for material comparison, selection, and routine quality control of polymeric parts and components.

Q: Is it current or superseded?

A: The current published revision is D635‑22 (published July 1, 2022) and is listed as an active ASTM standard. Users should verify if any later revisions or reapprovals have been issued after July 1, 2022 for their specific application.

Q: Is it part of a series?

A: D635 is one of several ASTM methods that address the burning and flammability behavior of plastics; it is often used together with related test methods (for vertical burning, oxygen index, thin film tests, etc.) to form a broader flammability test program for materials and components.

Q: What are the key keywords?

A: Key terms include horizontal burning rate, extent of burning, time of burning, plastics flammability, HB classification, ASTM D635, linear burning rate.