Electricity and Control July 2022

MEASUREMENT + INSTRUMENTATION : PRODUCTS + SERVICES

Top quality drinking water through ozone treatment

Drinking water is the most important food of all. And its preparation entails complex processes. To oxidise and disinfect drinking water, ozone is often mixed in during the course of treatment. Because of its high reactivity, ozone must be produced, transported and added to the water on-site, under strict safety regulations. In such applications, Vega’s pressure transducers make an im portant contribution to the continuous processing of top quality drinking water. Christian Langensiepen, Product Management, VEGA Grieshaber KG refers to the water supply sys tem in Baden-Württemberg, one of the largest and most far-reaching water supplies in Germany. It supplies 250 cities and municipalities with about 90 million cubic me tres of drinking water each year. Top quality and a high level of security of supply are priorities in the manage ment of the regional water supply system. At the beginning of the 20th century, the population in the central Neckar region was already growing rapidly as industrialisation progressed. The far-sighted plan at the time was to bring drinking water from the Danube valley at the city of Ulm, via the Remstal, to Stuttgart. This laid the foundation for the regional water supply system. Plants for the conversion of river water to drinking water include a raw water pump, which draws the water directly from the river, a pressure pipe from the pumping station to the waterworks, and the treatment facilities in the waterworks. At peak times, up to 2 300 litres of river water per second can be converted into drinking water. The injection of highly active oxygen (ozone) for oxida tion and disinfection during drinking water treatment rep resents state-of-the-art technology. Ozone oxidises dissolved and particulate organic mat ter and kills or inactivates existing microorganisms. Ozone is always formed when some form of energy decomposes molecular oxygen (O 2 ) into individual oxygen atoms (O), which then react with molecular oxygen (O 2 ) to form ozone (O 3 ). This can occur through UV radiation, lightning strikes and via high voltage electrical discharges. The production process takes place in pressurised re actors, where electrical energy is applied to convert ox The SDP air gap sensor from ifm measures air gaps with high repeat accuracy in the micrometre range. It detects the distance between the surface and object and outputs it as an absolute value. The sensor reliably detects even a flat position on the surface, the so-called ‘zero gap’. Since the gap is calculated on the basis of pressure and flow, the measurement remains consistently accurate at all times within the usual operating pressure range be tween 1 and 3 bars, irrespective of pressure fluctuations, or the number and diameter of the nozzles. It presents gap value, flow and pressure information at a glance.

The robust self-cleaning measuring chan nel also withstands purge air pressure. This eliminates the need to switch between flushing and measuring and has the further advantage of ensuring that the measuring element is cleaned and malfunctions due to contami nation are prevented. For more information contact ifm South Africa. Tel: +27 (0)12 450 0400 Email: info.za@ifm.com, visit: www.ifm.com ygen into ozone. The resulting gas mixture flows into an ozone collecting pipe. The maximum ozone concentration is about 180 g/Nm³ at an operating pressure of 1.3 bar. Injectors feed the ozone into the water, and mixers distribute the tiny ozone bubbles evenly through the wa ter volume. The water remains for a few minutes in large containers during which time oxidation and disinfection take place. To ensure that pressure measurement in the ozone collection pipe and at other important measuring points is absolutely safe and reliable, the engineering department decided to use Vegabar 82, the pressure transmitter with a ceramic CERTEC ® measuring cell and a ‘second line of defence’. This is an additional process separation by means of a gas-tight feedthrough above the process connection. Although the measuring cell is permanently resistant to ozone, the second line of defence provides an extra layer of protection against leakage of ozone from the pipeline through the pressure transmitter. In this way Vegabar 82 plays an important role in safe ozone generation as well as in the continuous production of top quality drinking water. For more information contact VEGA Controls SA. Tel: +27 (0)11 795 3249 Email: info.za@vega.com, visit: www.vega.com/en-za In pressurised reactors, electrical energy is applied to convert oxygen into ozone which is used in the production of safe drinking water.

Air gap sensor ensures accurate position monitoring

The SDP air gap sensor ensures

consistently accurate position monitoring, based on pressure and flow.

JULY 2022 Electricity + Control

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