Overview
EN ISO 9455-9:2020 - “Soft soldering fluxes - Test methods - Part 9: Determination of ammonia content” - specifies a validated distillation titration method for measuring ammonia in solid, paste or liquid soft‑soldering fluxes. The procedure applies only to fluxes of class 311 and 321 as defined in ISO 9454‑1. The standard is intended for use by testing laboratories and manufacturers to quantify ammonia expressed as mass % of ammonium chloride.
Key topics and technical requirements
- Scope & applicability: Method restricted to flux classes 311 and 321 (see ISO 9454‑1).
- Principle: Alkaline distillation (NaOH) expels ammonia from a prepared flux solution; ammonia is absorbed into a known volume of sulfuric acid and the remaining acid is back‑titrated with standardized NaOH using methyl orange indicator.
- Sample preparation:
- Solid/paste: weighed aliquots dissolved/diluted with water and an acid solution to clarity.
- Liquid: measured aliquots diluted to volume.
- Reagents & apparatus: Analytical grade reagents (NaOH, H2SO4, methyl orange), water‑cooled condenser and distillation assembly per standard figure. The document includes specified reagent concentrations and preparation guidance.
- Procedure controls: Tests carried out in triplicate; precise reagent volumes and distillation/titration steps are defined.
- Calculation & units: Results reported as percentage by mass of ammonium chloride. The standard gives the calculation formula and conversion factors (e.g., 1 ml of 0.5 mol/l H2SO4 ≈ 0.0535 g NH4Cl).
- Safety: Procedures involve concentrated acids and caustic solutions - appropriate laboratory safety and trained personnel required.
Applications and users
This standard is practical for:
- Flux manufacturers performing quality control and batch release testing.
- Independent testing laboratories and compliance/quality assurance (QA) units validating flux chemical composition.
- Electronics, plumbing and HVAC industries where soldering performance and residues are sensitive to ammonia content.
- Procurement and regulatory teams requiring documented test evidence that fluxes meet chemical specifications.
Benefits include consistent, repeatable ammonia quantification for product specification, process control, regulatory compliance, and compatibility assessment with soldering processes and substrates.
Related standards
- ISO 9454‑1 - classification and coding of fluxes (referenced for flux classes 311 and 321).
- Other parts of the ISO 9455 series (soft soldering flux test methods) - consult ISO for the complete series and complementary test procedures.
Keywords: EN ISO 9455-9:2020, soft soldering fluxes, ammonia content, test methods, distillation method, flux classes 311 321, soldering flux testing, ISO 9454‑1.
