The chlorination of potable water, wastewater effluents and cooling water is widely used throughout the world to control biological activity in water. Wastewater disinfection helps to ensure that receiving streams are safe for recreational use, and cooling water chlorination reduces biofouling that can degrade heat transfer efficiency. In addition to these common uses, there are several applications where chlorine addition helps to reduce biological contamination. Residual chlorine is found in many chemical forms in water systems and can contain mixtures of free chlorine, combined chlorine and organochlorine species.
Measurement of residual chlorine can be relatively difficult where a variety of chlorine forms exist, and a measurement of total residual chlorine is often required in these applications. Total chlorine in water has historically been measured by causing a reaction between the chlorine in a water sample and a quantity of potassium iodide. All of the various chlorine compounds react with the iodide to release an equivalent amount of iodine, and the released iodine can then be measured using a wide range of methods. Many on-line monitors for total residual chlorine use the iodometric method for measurement, often measuring current between two exposed electrodes to determine the iodine concentration.
ATI’s A15/79 Total Chlorine Monitor uses the iodometric method but with a membraned gas sensor rather than exposed electrodes for measuring the released iodine. This gas phase sensing method ensures that the iodine measurement is taken without contact between sample and electrodes, eliminating the potential for sensor fouling. This promotes longevity of the sensor which is protected from the contamination to which other sensors are prone and provides better stability.
The A15/79 monitor is an on-line automated chemistry system that provides the components necessary to perform total residual chlorine measurement. The Total Chlorine monitors consist of three separate components: a chemistry module; an inlet flow assembly where raw sample is delivered to the system; and an electronic readout containing the chlorine concentration display, analog output, and alarm contacts. Readout modules are available in either wall mount NEMA 4X or general purpose panel mount versions.
The ATI A15/79 monitor has a wide range of applications in the treatment of industrial trade effluents, cooling water and potable water.