Chlorine meter Diluting over range samples Learning Objectives

Chlorine meter- Diluting over range samples Learning Objectives At the end of this lesson you will be able to: • Dilute “over-range” samples To go to next page, click on Page- 1

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. To go to next page, click on Page- 2

Chlorine meter- Diluting over range samples Diluting “over-range” samples- using a measuring cylinder • A fresh sample is diluted with de-ionised water. • Pour 10 m. L of sample into a measuring cylinder. To go to next page, click on Page- 3

Chlorine meter- Diluting over range samples Fresh water sample diluted with de-ionised water • Add 10 m. L 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- 4

Chlorine meter- Diluting over range samples Measuring diluted samples Using the diluted sample, fill the cell exactly to the 10 m. L mark. The sample is ready for testing. Note: Very important step when measuring diluted samples. To go to next page, click on Page- 5

Chlorine meter- Diluting over range samples 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. To go to next page, click on Page- 6

Chlorine meter- Diluting over range samples 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- 6

Chlorine meter- 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) 1 Take 10 m. L of the DILUTED water sample 2 Add 10 m. L of de-ionised water and mix To go to next page, click on Page- 7

Chlorine meter- Diluting over range samples 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. To go to next page, click on Page- 8

Chlorine meter- 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- 8

Chlorine meter- Diluting over range samples Diluting “over-range” samples using 2 cells You will dilute the sample using the 10 m. L mark on the cell. 1. Fill a cell to the 10 m. L mark with sample. 2. Fill a second cell to the 10 m. L mark with de-ionised water To go to next page, click on Page- 9

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 m. L mark by carefully tipping some of the diluted sample out. 5. The sample is ready for testing. To go to next page, click on Page- 10

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) It’s vital to fill the cell to exactly 10 m. L mark when measuring volumes of sample or deionised water. d) All of the above Click here for answer. To go to next page, click on Page- 11

Chlorine meter- Diluting over range samples Quiz 1 - Answer Which of the following statements is true? d) All of the above To go to next page, click on Page- 11

Chlorine meter- Diluting over range samples Summary This section covered: Instructions for diluting “over-range” samples using: • • measuring cylinders 10 m. L HACH cells To return to first page, click on Page- 12