Overview
ISO 3363:1976 specifies a titrimetric method for determining the acidity of fluorochlorinated hydrocarbons for industrial use. The standard applies to products with acidity between 2 and 200 µmol of univalent acid per kilogram. It defines two operating procedures: one for liquid products (e.g., R11, R113) and one for gaseous/low‑boiling products (e.g., R12, R22, R114). The method is based on extraction of acid into water followed by volumetric titration with standardized sodium hydroxide in the presence of bromocresol green indicator.
Key Topics and Requirements
- Scope: Applicable range 2–200 µmol acid/kg for fluorochlorinated hydrocarbons used industrially.
- Principle: Water extraction of acidic components, followed by titration of the aqueous phase.
- Reagents:
- Distilled water neutral to bromocresol green.
- Sodium hydroxide titration solution, 0.01 N, standardized against 0.01 N HCl.
- Bromocresol green indicator, 1 g/L in 95% ethanol.
- Procedures:
- Liquids: Typical laboratory sample ~100 g (weighed to 0.1 g). Extract with cooled water where specified, collect aqueous phase and titrate.
- Gases / low‑boiling products: Use an absorption assembly (needle valve, bubble indicator, three Drechsel wash bottles in series) to pass the product vapour through 50 mL water in each flask, then titrate combined aqueous washings.
- Apparatus: Microburette (2 mL capacity, 0.01 mL graduations) for precise titration; Drechsel flasks and bubble indicator for gaseous absorption.
- Results: Standard provides formulas to report acidity as µmol univalent acid/kg, mg HCl/kg, and acid index in mg KOH/g. Report results with precision matching the weighing and titration steps.
- Sampling references: Compliance with ISO 2209 (liquids) and ISO 3427 (gaseous) for sampling is required.
Applications and Users
ISO 3363:1976 is used for quality control and regulatory compliance in:
- Manufacturers of halogenated hydrocarbons and refrigerants (e.g., R11, R12, R113, R22, R114).
- Analytical and quality laboratories performing acidity testing on fluorochlorinated products.
- Environmental and safety teams monitoring corrosive impurities in industrial chemicals.
- Procurement and standards departments verifying vendor material conformity.
Practical benefits include consistent acidity measurement, protection against corrosion or catalyst poisoning in downstream processes, and standardized reporting for batch acceptance.
Related Standards
- ISO/R 1393 - Determination of acidity (liquids)
- ISO/R 1394 - Determination of cloud point (liquids)
- ISO 2209 - Sampling (liquids)
- ISO 2210 - Determination of residue on evaporation (liquids)
- ISO 3427 - Sampling of liquefied gases
Keywords: ISO 3363:1976, fluorochlorinated hydrocarbons acidity, titrimetric method, sodium hydroxide titration, bromocresol green, Drechsel flasks, R11 R12 R113 R22 R114, acid determination, halogenated hydrocarbons quality control.
Open preview (PDF)Fluorochlorinated hydrocarbons for industrial use — Determination of acidity — Titrimetric method