Measuring Chlorine

Measurement of chlorine in the field is relatively easy. The fact that chlorine can be easily detected and measured makes chlorine a favorite water sanitizer for those concerned with the safety of water supplies, public and private pools, and other sources or reservoirs. Chlorine concentrations in the range of 0.1 to 0.4 parts per million are usually maintained in municipal supplies, while ranges from 1 to 3 ppm are used in both pools and spas.

Three types of chlorine can be measured:

  • Free chlorine – most effective as a disinfectant
  • Combined chlorine – formed when free chlorine reacts with other compounds within the water.
  • Total chlorine – the sum of free and combined chlorine.

Since free chlorine is the primary disinfectant, a means of measuring free chlorine is needed.

Chlorine Test Method

The method used for measuring chlorine residuals uses a chemical compound called DPD (N,N-Diethylparaphenylenediamine), either through the use of a chlorine comparator or photometric instrument (this provides the highest accuracy and precision for measuring chlorine residuals). This compound can be provided as a tablet or as a liquid. DPD reacts instantly to produce a red color in the presence of chlorine. The subsequent addition of potassium iodide evokes a rapid color response from the combined forms of chlorine (typically chloramines).

Test strips utilize a different indicator as a means of measuring chlorine..

Octa-Slide 2Comparators

A color comparator allows the individual testing for chlorine to compare the reacted sample with established color standards, thereby determining the concentration of chlorine in the sample. The tester simply places the reacted sample in the comparator, comparing the sample to the colors in the sidebar, thereby determining the concentration of the chlorine in the sample.

2063 200x200

Instruments

A colorimeter passes a white light beam through an optical filter which transmits only one particular color or band of wavelengths of light to the photodetector, where it is measured. The difference in the amount of colored light transmitted by a colorless sample (blank), and the amount of colored light transmitted by a colored sample, is a measurement of the amount of colored light absorbed by the sample. In most colorimetric tests, including chlorine, the amount of colored light absorbed is directly proportional to the concentration, and is reported by the meter.

Analytic Test StripsTest Strips

Utilizing a different indicator, test strips are small strips, typically produced from plastic, with chemically impregnated pads on the end. These pads are designed to react with specific ions and produce a specific color change. Once a test strip is reacted, and a color is developed, the strip is then compared to a printed color chart. The printed color chart is specifically designed to represent color reactions at various concentrations. Matching the strip to the closest color match produces a concentration reading.

 

 

Chlorine Testing Products

 

Test Strips

4250-bj

Chlorine Test Papers

Order Code: 4250-BJ
Applications: Water and Wastewater, Industrial Water Boiling and Cooling, Drinking Water, Laundry and Sanitation

Chlorine test papers are chemically treated to indicate sanitizer levels. Range and sensitivity is 10, 50, 100, 200 ppm (200 strips).


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30312

Free Chlorine High Range Test Strips

Order Code: 3031
Applications: Water and Wastewater, Industrial Water Boiling and Cooling, Laundry and Sanitation

The Insta-Test High Range Chlorine test strips are a convenient way to test water for high range levels of Free Chlorine. Range and sensitivity is 0, 50, 100, 250, 500, 800 ppm.


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2964g-free-chlorine

Free Chlorine Low Range Test Strips

Order Code: 2964-G
Applications: Pool and Spa, Drinking Water, Industrial Water Boiling and Cooling, Water and Wastewater

The Insta-Test Low Range Chlorine test strips are a convenient way to test low range levels of Free Chlorine. Ideal for drinking water or pools. Range and sensitivity is 0, 0.5, 1, 3, 5, 10 ppm.


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Total Chlorine Low Range Test Strips

Total Chlorine Low Range Test Strips

Order Code: 2963LR-G
Applications: Pool and Spa, Drinking Water, Industrial Water Boiling and Cooling, Water and Wastewater

The Insta-TEST® Low Range Total Chlorine test strips are a convenient way to test water for low range levels of Total Chlorine. Range and sensitivity is 0, 0.25, 0.5, 1, 3, 10 ppm.


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Total Chlorine Test Strips

Total Chlorine Test Strips

Order Code: 2979
Applications: Drinking Water, Industrial Water Boiling and Cooling, Laundry and Sanitation, Water and Wastewater

The Insta-TEST® Total Chlorine test strips are a convenient way to test water for Total Chlorine. Range and sensitivity is 0, 0.5, 1, 3, 5 ppm.


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2976-plus

Insta-TEST® 3 Plus

Order Code: 2976
Applications: Pool and Spa

The Insta-TEST 3 Plus pool & spa strip measures Free Chlorine 0-10 ppm, Bromine 0-20 ppm, Total Alkalinity 0-240 ppm, and pH 6.2-9.0. This test strip is a dip-n-read strip with instant results.


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2977plus6

Insta-TEST® 5 Plus

Order Code: 2977
Applications: Pool and Spa

The Insta-TEST 5 Plus pool & spa strip measures Free Chlorine 0-10 ppm, Bromine 0-20 ppm, Total Chlorine 0-10 ppm, Total Alkalinity 0-240 ppm, pH 6.2-9.0, and Total Hardness 0-800 ppm.


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2978-plus

Insta-TEST® PRO 400 Plus

Order Code: 2978
Applications: Pool and Spa

Insta-TEST PRO 400 Plus measures Free Chlorine 0 to 10 ppm, Bromine 0 to 20 ppm, Total Chlorine 0 to 10 ppm, Alkalinity 0 to 240 ppm and pH 6.2 to 9.0 with instant results.


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Test Kits

3314-018

Dual Range Chlorine Test Kit

Order Code: 3314-01
Applications: Drinking Water, Food and Beverage, Industrial Water Boiling and Cooling, Laundry and Sanitation, Water and Wastewater

This kit tests for high and low ranges of Chlorine using the Octa-Slide 2 Comparator.


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7514-01

FAS-DPD Chlorine Test Kit

Order Code: 7514-01
Applications: Pool and Spa

The DPD-FAS titration test kit measures Free and Total Chlorine in 0.2 ppm and 0.5 ppm increments. The distinct color change allows for accurate readings even at very low or high chlorine levels.


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No image set

High Range Chlorine Test Kit

Order Code: 3328-01
Applications: Industrial Water Boiling and Cooling, Water and Wastewater

This Chlorine test kit measures for high ranges of Chlorine using Chlorine DPD tablets and the Octa-Slide 2 Comparator. Range/sensitivity is 1.0-10.0 ppm Cl.


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3308-01

DPD Free,Total & Combined Chlorine Test Kit

Order Code: 3308-01
Applications: Drinking Water, Environmental Education, Food and Beverage, Industrial Water Boiling and Cooling, Laundry and Sanitation, Water and Wastewater

This Chlorine test kit measures free, total & combined Chlorine using Chlorine DPD tablets and the Octa-Slide 2 Comparator. Range/sensitivity is 0.2 - 3.0 ppm Cl.


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Instruments

1740

Total Chlorine TRACER

Order Code: 1740
Applications: Industrial Water Boiling and Cooling, Laundry and Sanitation, Water and Wastewater

The electronic TCl TRACER measures Total Chlorine levels with a range from 0.00 to 9.99 ppm. Includes an interchangeable sensor for pH & Orp readings.


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2063

High Range Chlorine ColorQ

Order Code: 2063
Applications: Food and Beverage

The LaMotte ColorQ meter is a simple way to test low and high concentrations of chlorine.


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