High Accuracy, Less Chemistry

A multiparameter online chlorine analyzer from Thermo Fisher Scientific helps water and wastewater facilities get reliable readings while using significantly less reagent.
High Accuracy, Less Chemistry
The analyzer is suitable for water and wastewater and a variety of industrial applications.

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Accuracy matters greatly in online chlorine measurement, but so does the cost of the measurement device and the reagents it consumes.

The Thermo Scientific Orion Chlorine XP analyzer from Thermo Fisher Scientific is designed to combine high performance with low lifetime cost of ownership. Its applications include drinking water and wastewater treatment plants and a variety of industrial processes.

Depending on the user’s chosen configuration, the device can measure free chlorine, total chlorine, or both. Its colorimetric functionality minimizes periodic recalibrations and is compatible with all disinfectant systems. Manav Randhawa, the company’s product manager for process water analysis instruments, talked about the technology in an interview with Treatment Plant Operator.

TPO: What was the main market need this analyzer was designed to address?

Randhawa: A key comment we heard from users of analyzers was the consumption of reagent. We set out to create an analyzer that would target that customer pain point. This analyzer allows users to customize the reagent mixing, so that based on a five-minute test cycle time, the reagent can last up to two months, versus the 30-day duration that is more typical today. So the cost of ownership from a reagent point of view is essentially cut in half.

TPO: In dollars and cents, how significant is this potential cost savings?

Randhawa: Let’s assume that each reagent replacement costs $50. If the reagent is replaced monthly and the analyzer lasts six years, then the lifetime cost of that reagent is $50 times 72 months, or $3,600. If we can extend that replacement interval to two months, we can reduce that by half. That’s the cost of ownership savings the customers were looking for.

TPO: How exactly does this analyzer draw and test samples?

Randhawa: The analyzer uses colorimetric DPD chemistry. The sample is first filtered and then admitted to a sample chamber by way of an automatic solenoid valve. A peristaltic pump then delivers reagents to the sample chamber. A piston inside the chamber moves vertically to mix the reagents and the sample.

Once a homogenous mixture has been created, a light beam passes through the chamber, and the color is measured to determine how much chlorine is present in the sample. After the reading is taken, the sample is ejected, and the piston completes a couple more vertical cycles with a fresh sample to make sure the chamber is clean, so that accuracy is sustained from one sample to the next. A unique feature of this unit is that if there is no sample flow, the analyzer will alarm and shut down.

TPO: How would you describe the accuracy of this unit?

Randhawa: One attribute of this analyzer is that the intensity of light changes or self-calibrates with the new sample intake. For example, if there is a more impure or turbid sample, the light beam intensity automatically increases. That increases the accuracy of the analyzer. We can achieve resolution down to 10 parts per billion, within a measurement range of zero to 10 parts per million.

TPO: How many parameters can this device measure?

Randhawa: It can be configured to measure up to four parameters — free chlorine, total chlorine, pH and temperature. This reduces the need for customers to purchase multiple analyzers.

TPO: What maintenance does this device require?

Randhawa: The maintenance on this analyzer is low. We recommend a yearly maintenance kit. All that needs to be replaced is the filter and the pumps. The automated cleaning of the sample chamber, besides enhancing accuracy, reduces the time required by the customer to make sure the chamber is clean. The chamber does not need to be replaced as part of annual maintenance.

In our field tests, this unit has performed very well even in wastewater applications where the samples are quite dirty.

TPO: Does this unit have applications beyond the water and wastewater sectors?

Randhawa: It is suitable for a variety of industrial applications, including for bottling plants, cooling towers, and for life extension in reverse osmosis skids, to make sure the feedwater is free of chlorine that would damage the membranes.


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