Overview
ISO 2120:1972 is an internationally recognized standard published by the International Organization for Standardization (ISO) that specifies a reliable method for determining the chlorine content by volume in vaporized liquid chlorine used for industrial purposes. This standard focuses on the accurate volumetric analysis of gaseous chlorine obtained by gasifying liquid chlorine samples, providing essential guidance for the chemical and industrial sectors that rely on safe and precise chlorine content measurements.
The procedure involves sampling a known volume of vaporized chlorine, absorbing the chlorine using a 2% zinc amalgam solution, and measuring residual non-condensable gases. The chlorine content is then calculated from the difference in volumes, ensuring high accuracy of results critical for quality control and safety compliance in industrial chlorine handling.
Key Topics
- Sampling and gasification – Vaporizing a precise volume (~100 ml) of liquid chlorine to obtain a representative gas sample.
- Absorption method – Utilizing 2% zinc amalgam in the presence of saturated sodium chloride solution to absorb chlorine from the vapor phase efficiently.
- Measurement of residual gases – Quantifying non-condensable gases such as hydrogen (H2), oxygen (O2), nitrogen (N2), carbon monoxide (CO), and carbon dioxide (CO2) to identify the chlorine volume by difference.
- Apparatus setup – Detailed configuration of specialized equipment including gas burettes, steel needle valves, zinc amalgam flasks, levelling bottles, bubblers, stopcocks, and safety containers designed for handling corrosive chlorine safely.
- Safety precautions – Comprehensive safety measures for personnel working with toxic, vesicatory, and irritant chlorine gas, including ventilation requirements, protective clothing, and emergency procedures to mitigate exposure risks.
- Calculation formula – Standardized expression of chlorine content as a percentage by volume based on volumetric readings of initial and residual gases.
- Cleaning and maintenance – Proper cleaning protocols using sulfuric acid, distilled water, and methanol to maintain apparatus accuracy and longevity.
Applications
ISO 2120:1972 is essential in industries where liquid chlorine is employed, ensuring product quality and safety through precise chlorine content measurement:
- Chemical manufacturing – For accurate chlorine dosing in production processes such as bleaching agents, disinfectants, and intermediates synthesis.
- Water treatment facilities – To verify chlorine levels for effective disinfection ensuring safe potable water supply.
- Pharmaceuticals – Controlling chlorine purity and concentration in chemical synthesis and sterilization procedures.
- Environmental monitoring – Assessing chlorine release and emissions for regulatory compliance and environmental protection.
- Industrial gas suppliers – Providing certified chlorine gas volumes for customer assurance and contractual guarantees.
- Safety management – Implementing controlled handling practices to prevent occupational hazards from chlorine exposure.
Related Standards
To complement and reinforce the application of ISO 2120:1972, organizations typically refer to:
- ISO 3262 series – Specifications for liquefied chlorine industrial products including packaging and transport.
- ISO 5667-15 – Water quality sampling standards relevant when chlorine content impacts water treatment processes.
- EN 1911 – European standards for chlorine gas detection and monitoring equipment.
- OSHA regulations – Guidelines for occupational exposure limits and safety practices when working with hazardous gases such as chlorine.
- ANSI/ASHRAE standards – For ventilation and air quality controls in industrial settings handling toxic chemicals.
ISO 2120:1972 ensures a standardized, reproducible method for chlorine volumetric analysis, integrating precise chemical techniques with essential safety protocols. Adopting this standard promotes operational excellence, regulatory compliance, and environmental responsibility in all industries handling liquid chlorine.
Open preview (PDF)Liquid chlorine for industrial use — Determination of the content of chlorine by volume in the vaporized product
