Dissolved Ozone Measurements: Installation And Calibration According To ASTM D7677-11

By Georges Schmidt, Hach Lange Sàrl, Geneva, Switzerland

In the last three decades Ozone has become a very important and efficient tool to achieve high quality pharmaceutical grade water. There are several resons for this: Firstly, because of the quick, broad and powerful sanitization efficiency. Secondly, because it is easy to generate ozone directly in water without creating by-products. Thirdly, because it is easy to remove it with a 254nm UV light, a positive consequence of ozone’s limited lifetime in water. And, last but not least, the use of ozone also helps to reduce costs when compared to other techniques of water sanitization.

This paper will address two main topics that are critical for the effective use of ozone within the water processes of the life science industry. First, two main installation variants of ozone monitoring in process water will be identified. Second, calibration methods will be discussed, including air calibration. These topics are now well described in the ASTM D7677 Standard Method (1) published in 2011.

Sensors are available using either UV absorption or electrochemical (EC) technologies. We will focus here on this last technology that is also described in the ASTM D7677-11 standard.