Chlorine Meter or Portable DPD Colorimeters

A Chlorine Meter or a DPD Colorimeter is a device designed to measure the Free Chlorine or Total Chlorine in a sample.

Our range of Chlorine Meters are DPD Colorimeter type chlorine meters, which means that a grab sample is taken from the solution to be measured, and then inserted into the Chlorine Meter. An amount of the reagent DPD (N,N Diethyl-1,4 Phenylenediamine Sulfate) is added to the sample which changes to a shade of pink, in the presence of chlorine. When this sample is analysed by the chlorine meter or colorimeter, the absorption rate of a specific wavelength of light (approx 525 nm) is measured, which correlates to the PPM of chlorine within the sample.

Portable Chlorine Meter, Free Chlorine and Total Chlorine

When measuring a sample of a solution for chlorine content, depending upon our application we can measure either Free Chlorine or Total Chlorine.

Free chlorine is normally measured as part of a disinfection process, whether in drinking water, swimming pools, water treatment, or industrial processes and is expressed in PPM or mg/L.

Total Chlorine is the combination of Free Chlorine and Combined Chlorine (Chloramines normally produced in the presence of ammonia, normally monochloramine and dichloramine, but also trichloramine as described on the Chlorine page). Total chlorine is normally measured as part of some waste water treatment processes to ascertain the total combined amount of chlorine present in a system. There is some on-going debate about the use of Chloramines in the disinfection process.

We can measure both Free Chlorine and Total Chlorine using a portable DPD Colorimeter. We simply use a different reagent with our sample and instruct our chlorine meter to check the absorption spectrum. There is a specific reagent for use with Free Chlorine, and a specific reagent for use with Total Chlorine. Both types are readily available from AWE and are supplied with our portable chlorine meter kits.

Portable Chlorine Meter Calibration

Portable Chlorine Meter calibration is a tricky process. Thankfully, the chlorine meters only need to be calibrated once, at the factory, before they are shipped for use.

The instruments can be re-calibrated by the user if required, however, we advise against this and offer a free service of calibrating the instruments back to factory conditions if required.

Portable Chlorine Meter Range