SIST EN 16399:2014

Overview

SIST EN 16399:2014 is a European Standard developed by CEN that specifically addresses sodium thiosulfate used in the treatment of swimming pool water. This standard defines the chemical's characteristics, quality requirements, and test methods to ensure the safety and effectiveness of sodium thiosulfate as a pool water treatment chemical. Importantly, this standard applies exclusively to pure sodium thiosulfate and does not cover mixtures containing other chemicals.

The document also provides guidance on the safe handling, transportation, and storage of sodium thiosulfate to protect users and maintain product integrity. SIST EN 16399:2014 supports uniform quality control and regulatory compliance across European markets for this chemical.

Key Topics

• Chemical Identification
  Sodium thiosulfate is recognized by the CAS Registry Numbers 7772-98-7 (anhydrous) and 10102-17-7 (pentahydrate) with the empirical and chemical formula Na₂S₂O₃. It is also known as sodium hyposulfite.

• Physical and Chemical Properties
  The standard characterizes sodium thiosulfate in its commercial forms, mainly as a colourless crystalline powder (pentahydrate) or white powder (anhydrous), with particle density ranging from 1.69 to 1.73 g/cm³ at 20 °C.
  Solubility is significant, with anhydrous sodium thiosulfate dissolving at 700 g/l at 20 °C and the pentahydrate at 2910 g/l at 45 °C. The product begins to decompose thermally between 45 °C and 50 °C.

• Purity and Test Methods
  The standard specifies impurity limits and defines test procedures to verify compliance, ensuring the chemical meets safety and performance criteria required for pool water treatment.

• Safe Handling and Use
  Annex A of the standard provides comprehensive safety guidelines related to the storage, transport, and handling of sodium thiosulfate to minimize health and environmental risks.

• Regulatory Compliance
  SIST EN 16399:2014 aligns with EU legislation on labelling and transportation, ensuring sodium thiosulfate products conform to European regulatory frameworks.

Applications

Sodium thiosulfate is widely used in swimming pool water treatment primarily for its ability to neutralize residual chlorine and control water quality. Its application includes:

• Chlorine Neutralization: Neutralizing excess chlorine following shock treatments or in emergency spill scenarios to prevent skin irritation and damage to pool infrastructure.
• Water Purification: Enhancing water quality by reducing residual oxidizing agents, thus improving swimmer comfort and safety.
• Regulatory Compliance: Maintaining pool water parameters within legal limits by controlling disinfection byproducts through chemical stabilization.

This chemical supports public health protection in pools by helping maintain chemically balanced and safe swimming environments.

Related Standards

• EN 12125: This related standard covers sodium thiosulfate used for treatment of water intended for human consumption, establishing additional purity and safety requirements relevant to drinking water.
• CEN/TC 164 Water Supply Standards: EN 16399 is part of a broader framework of European standards addressing water treatment chemicals and technologies for both industrial and recreational water supplies.

Summary

SIST EN 16399:2014 sets the benchmark for quality, safety, and performance of sodium thiosulfate used in swimming pool water treatment. By standardizing chemical specifications, purity criteria, and safe handling practices, it facilitates reliable use of this essential chemical across Europe. Pool operators, chemical manufacturers, and regulatory bodies benefit from this document through enhanced clarity, regulatory alignment, and improved health safety outcomes.

Keywords: EN 16399, sodium thiosulfate, swimming pool water treatment, water purification, chlorine neutralization, chemical safety, European standard, pool chemical standards, water treatment chemicals, CEN standards.