To go to next page, click on Page- Chlorine meter- Diluting over range samples Learning Objectives At the end of this lesson you will be able to: Dilute over-range samples 1 To go to next page, click on Page- Chlorine meter- Diluting over range samples Diluting over-range samples If a sample turns yellow after adding the DPD powder or if the display flashes 2.20 then the water sample must be DILUTED. 2 To go to next page, click on Page- Chlorine meter- Diluting over range samples 3 Diluting over-range samples- using a measuring cylinder A fresh sample is diluted with de-ionised water. Pour 10 mL of sample into a measuring cylinder. To go to next page, click on Page- Chlorine meter- Diluting over range samples 4 Fresh water sample diluted with de-ionised water Add 10 mL of de-ionised water and mix carefully without splashing by swirling. The sample is ready for testing. To go to next page, click on Page- Chlorine meter- Diluting over range samples 5 Measuring diluted samples Using the diluted sample, fill the cell exactly to the 10 mL mark. The sample is ready for testing. Note: Very important step when measuring diluted samples. To go to next page, click on Page- Chlorine meter- Diluting over range samples 6 Measuring diluted samples Remember to multiply your results by 2 to get the correct concentration for the water sample. Why do we need to do this? Click here for answer.here To go to next page, click on Page- Chlorine meter- Diluting over range samples 6 Measuring diluted samples Remember to multiply your results by 2 to get the correct concentration for the water sample. Why do we need to do this? Because you halved the concentration of chlorine with the dilution. To go to next page, click on Page- Chlorine meter- Diluting over range samples 7 Diluting over range samples If the sample is still over-range, you may dilute it a second time as described. (This is called a double dilution you should not dilute more than twice) Take 10 mL of the DILUTED water sample Add 10 mL of de-ionised water and mix 12 To go to next page, click on Page- Chlorine meter- Diluting over range samples 8 Diluting over-range samples Use the twice diluted sample for your analysis. Remember to multiply the result by 4 to get the correct chlorine concentration. Why do we need to do this? Click here for answer.here To go to next page, click on Page- Chlorine meter- Diluting over range samples 8 Diluting over range samples Use the twice diluted sample for your analysis. Remember to multiply your result by 4 to get the correct chlorine concentration. Why do we need to do this? The sample is 4 times weaker so the correct chlorine value will be 4 times greater than displayed result. To go to next page, click on Page- Chlorine meter- Diluting over range samples Diluting over-range samples using 2 cells You will dilute the sample using the 10 mL mark on the cell. 1.Fill a cell to the 10 mL mark with sample. 2.Fill a second cell to the 10 mL mark with de-ionised water 9 To go to next page, click on Page- Chlorine meter- Diluting over range samples Diluting over-range samples using 2 sample cells 3.Add the de-ionised water to the sample cell, cap and mix carefully. 4.Adjust the level to the 10 mL mark by carefully tipping some of the diluted sample out. 5.The sample is ready for testing. 10 To go to next page, click on Page- Chlorine meter- Diluting over range samples Quiz- Question 1 of 1 Which of the following statements is true? a) If the chlorine meter display flashes 2.20, the sample is too concentrated. b) When diluting the sample for the 1 st time, for correct concentration, multiply result by 2. c) Its vital to fill the cell to exactly 10 mL mark when measuring volumes of sample or deionised water. d) All of the above Click here for answer.here 11 To go to next page, click on Page- Chlorine meter- Diluting over range samples Quiz 1- Answer Which of the following statements is true? d) All of the above 11 To return to first page, click on Page- Chlorine meter- Diluting over range samples Summary This section covered: Instructions for diluting over-range samples using: measuring cylinders 10 mL HACH cells 12