Comparability Study between Digital and Visual Colorimeter by using of Chlorine Indicators of DpD No.1 and DpD No.3 under practical conditions


All public drinking water system was required to measure the levels of residual chlorine in a practically accurately instruments to ensure that the water was adequately disinfected. This experimental study was carried out to compare under practical condition in laboratory the test results of free and total chlorine in the water samples between digital colorimeter and visual colorimeter by using of chemical indicatorreagentsof ((DpD number (1)) for testing of free chlorine in water samples, and ((DpD number (3)) for testing of total chlorine in water samples. The experiments lasted from (1/10/2011 to 1/5/2012). The study was conducted in the Laboratories of Al-Kufa Technical Institute in Al-Kufa city that belong to Al-Najaf governorate about 165 Km to the south of Baghdad, and 60 km to the south of Babylon governorate.200 experiments were done in the laboratory, by made of 2 experiments in each day through a standards laboratory conditions. There was a highly statistical significant difference (p=0.000), in comparing between digital calorimeter and visual colorimeter of both free and a total chlorine test results. There was a highly differences in the mean when was comparison of the digital colorimeter with the visual colorimeter of both all free and total chlorine experiment. There was a strong direct correlation between digital colorimeter experimental results and contact time in both all free and total chlorine experiments, while there was a weak direct correlation between visual colorimeter and contact time in all free and total chlorine experiments. From the all tested results of experiment that was derived from this study, the study recommend to practically adaptation of a digital colorimeter instead of visual colorimeter in all the chlorine residual test results that was done by ministry of health inspectors in all governorates in monitoring of drinking water, and for more accurate and sensitive test result we recommend to adapted of digital colorimeter in all researches when tracing of chlorine residual of different water samples.