Overview
ISO 1689:1976 is an international standard that provides the formula for calculating the ratio of silicon dioxide (SiO₂) to sodium oxide (Na₂O) or potassium oxide (K₂O) in sodium and potassium silicates used for industrial applications. This standard ensures consistent and accurate evaluation of these silicate materials by focusing specifically on the oxides combined in the silicate form. It replaces the earlier ISO Recommendation R 1689-1970 and is part of a series of ISO standards that govern the analysis and characterization of sodium and potassium silicates.
Key Topics
- Scope and Purpose: The standard specifies how to calculate the SiO₂ to Na₂O or K₂O ratio in industrial sodium and potassium silicates, focusing exclusively on oxides present in silicate compounds, excluding other forms like carbonates.
- Chemical Components Considered:
- Silicon dioxide (SiO₂) content
- Sodium oxide (Na₂O) or potassium oxide (K₂O) content combined in silicates
- Differentiation from carbonate forms such as sodium carbonate (Na₂CO₃) and potassium carbonate (K₂CO₃)
- Calculation Methodology:
- Uses data from related ISO standards regarding total alkalinity, silica content, and carbonate content (ISO 1690, ISO 1691, ISO 1692)
- Defines the calculation by subtracting carbonate-bound oxides to isolate oxide content in silicates
- Provides ratios expressed by mass and molar ratios for precise chemical characterization
- Test Reporting Requirements:
- Methods and references used for measurement
- Results and format of data expression
- Documentation of any unusual features or optional procedures during testing
Applications
ISO 1689:1976 serves as an essential reference for industries and laboratories involved with:
- Chemical manufacturing: Accurate measurement of silica and alkali oxide ratios in silicate materials affects product performance in detergents, adhesives, and sealants.
- Glass and ceramics production: Controlling the SiO₂/Na₂O or SiO₂/K₂O ratio is critical in formulating raw materials for consistent quality and durability.
- Water treatment: Sodium and potassium silicates are widely used in water treatment, and adherence to this standard supports effective process control.
- Quality control laboratories: Ensures uniformity in testing methods and comparability of results across different labs and countries.
- Research and development: Provides a baseline formula for scientists studying silicate chemistry and formulating new industrial products.
Related Standards
ISO 1689 is part of a comprehensive ISO framework for the analysis of sodium and potassium silicates, including:
- ISO 1690: Determination of silica content by gravimetric method
- ISO 1691: Determination of carbonate content by gas-volumetric method
- ISO 1692: Determination of total alkalinity by titrimetry
- ISO 1686 to ISO 2124 series: Additional methods covering sample preparation, density determination, dry matter analysis, viscosity measurement, and impurity content like sulphates and iron
These related standards complement ISO 1689 by providing standardized testing protocols necessary for the accurate assessment of silicate raw materials.
ISO 1689:1976 ensures precise calculation of the silica to alkali oxide ratio in sodium and potassium silicates, facilitating quality assurance and consistency in industrial manufacturing. By harmonizing chemical analysis methods, this standard plays a crucial role in the production and application of silicate-based materials worldwide.
Open preview (PDF)Sodium and potassium silicates for industrial use — Calculation of the ratio : silicon dioxide/sodium oxide or silicon dioxide/potassium oxide