Overview
ISO 11127-7:2022 specifies laboratory and field test methods for the determination of water-soluble chlorides in non-metallic blast-cleaning abrasives used in the preparation of steel substrates before paint or coating application. Part of the ISO 11127 series, this third edition updates the standard to include three validated analytical routes: amperometric titration, spectrophotometry, and ion chromatography. The standard defines sample preparation, duplicate testing, calculation formulas and required reporting information.
Key topics and requirements
- Scope: Applicable to water-soluble chloride analysis in non‑metallic abrasives; complements the ISO 11126 series that defines abrasive types and requirements.
- Sampling: Representative sampling is required in accordance with ISO 11127-1.
- Sample extraction: Typical test portion is (100 ± 0.1) g extracted with (100 ± 0.5) ml water, shaken and allowed to settle or filtered.
- Analytical methods:
- Amperometric titration (silver nitrate) - established method; end point detected amperometrically; calculation formula provided for percent chloride.
- Spectrophotometry (mercuric thiocyanate / ferric nitrate) - colorimetric method measuring ferric thiocyanate absorbance around 450–460 nm; sensitive down to about 0.1 mg/L; suitable for portable/field spectrophotometers and reagent kits.
- Ion chromatography - separation and conductivity detection of chloride (and other anions); also sensitive to ≈0.1 mg/L; recommended filtration (0.45 μm) and pretreatment when high metal content is present.
- Reagents and apparatus: Specifies use of analytical-grade reagents (e.g., silver nitrate solution, mercuric thiocyanate/ferric nitrate reagents), membrane filter 0.45 µm, spectrophotometer, amperometric titration equipment, and a standard ion chromatograph system.
- Quality control: Perform determinations in duplicate; if results differ by >10% (relative), repeat extraction and analysis. Report mean to nearest 0.0001 %.
- Test report content: Identification of product, method used, result, deviations, unusual features, test date and analyst name, and reference to ISO 11127-7:2022.
Applications and users
ISO 11127-7:2022 is directly applicable to:
- Coating and surface-preparation laboratories verifying abrasive cleanliness before blast-cleaning.
- Quality control teams and paint applicators ensuring acceptable chloride levels to prevent corrosion under coatings.
- Abrasive manufacturers certifying products for steel surface preparation.
- Inspection bodies and contractors who need traceable, standardized chloride test results for specification compliance.
Keywords: ISO 11127-7:2022, water-soluble chlorides, non-metallic blast-cleaning abrasives, amperometric titration, spectrophotometry, ion chromatography, preparation of steel substrates.
Related standards
- ISO 11127-1 - Sampling for non-metallic blast-cleaning abrasives
- ISO 11126 (all parts) - Specifications for non-metallic blast-cleaning abrasives
- ISO 10304-1 - Ion chromatography for dissolved anions (referenced for IC method)
Open preview (PDF)Preparation of steel substrates before application of paints and related products — Test methods for non-metallic blast-cleaning abrasives — Part 7: Determination of water-soluble chlorides