ISO 3262-20:2021 PDF

Overview

ISO 3262-20:2021 - “Extenders - Specifications and methods of test - Part 20: Fumed silica” specifies quality requirements and corresponding laboratory test methods for fumed (pyrogenic) silica used as an extender or raw material. The second edition updates classification, test methods and limits for critical parameters such as silica content, inorganic oxide impurities, carbon and chloride content, loss on ignition and pH. It also defines sampling and analytical procedures to ensure consistent product quality.

Key topics and technical requirements

• Scope: Requirements and test methods specifically for fumed silica (amorphous silica produced by high‑temperature flame hydrolysis).
• Quality grades: The standard distinguishes at least two grades (e.g., Grade A and Grade B) with different limits for certain properties.
• Principal characteristics and limits (examples from Table 1):
  • Silica content: minimum 99.8% (by mass).
  • Oxide impurities: maximums for Al2O3 (~0.05%), TiO2 (~0.03%) and Fe2O3 (~0.003%).
  • Carbon content: criteria differentiating grades (e.g.,