Understanding and Measuring Deionized Water Quality: A Comprehensive Guide

In this article, we cover the crucial aspects of measuring the quality of deionized water.

Dissolved solids are removed when feed water goes through a purification process, such as deionization or reverse osmosis. These dissolved solids can include calcium, magnesium, chloride, and silica.

Importance of Measuring Dissolved Solids

By accurately measuring dissolved solids, we can assess how well the water treatment methods have performed. It is crucial to measure the quality of deionized water to ensure the effectiveness of purification processes. Measuring quality also helps maintain stringent water quality standards for industrial applications reliant on high-purity water deionized water.

Methods of Measurement

The most precise method of measurement involves evaporating a water sample and weighing the residue with a precision analytical balance. However, this approach is impractical because it is time-consuming and expensive.

An alternative and more practical method is to measure electrical conductivity. This method relies on the fact that dissolved solids facilitate the transfer of electrons through water. As dissolved solids decrease (as in highly purified water), electrical resistivity increases, and conductivity decreases. Conversely, higher concentrations of dissolved solids lead to higher conductivity and lower resistivity.

Practical Tools for Measurement

  1. Quality Lights: These devices indicate water quality based on resistivity thresholds. For instance, a red light may signify resistivity above a specified level (e.g., 200 kilo ohms), while a green light indicates water quality below that threshold. While convenient, quality lights do not provide specific resistivity values.
  2. Handheld Meters: Devices like the Myron L 4P offer portability and measure parameters such as conductivity, resistivity, and total dissolved solids (TDS). They are versatile but may be less accurate than inline devices due to environmental factors affecting the water sample.
  3. Inline Measurement Devices: Considered the gold standard for accuracy, inline devices like the Mettler Toledo M300 or M800 provide real-time measurements by inserting a probe directly into the water line. They offer precise values for conductivity, resistivity, and other parameters, making them ideal for continuous monitoring and control applications.

Choosing the Right Tool

Selecting the appropriate measurement tool depends on your specific needs for accuracy, convenience, and application. For precise and continuous monitoring, inline devices are recommended, whereas handheld meters offer portability with slightly reduced accuracy.

The Importance of Water Quality Measurement 

Accurately measuring dissolved solids in deionized water is crucial for ensuring quality and efficiency in industrial processes. Whether using quality lights for quick assessments or sophisticated handheld and inline devices for detailed measurements, choosing the right method empowers industries to maintain optimal water quality standards and operational efficiency.

By understanding these measurement techniques, industries can confidently manage their water purification processes to meet stringent quality requirements and regulatory standards.