Note: Chlorinated product — add 3 drops of Sodium Thiosulphate in Step 2.
| Concentration | 0.5 g/L | 1.0 g/L | 1.5 g/L | 2.0 g/L | 3.0 g/L | 6.0 g/L |
|---|---|---|---|---|---|---|
| Drops |
Instructions
- Fill the test tube to the 5 ml mark with water from the wash tank.
- Add 3 drops of Sodium Thiosulphate.
- Add 1 drop of Indicator Reagent — solution will turn pink.
- Select the correct acid by reference to table 3 (ACID 3 is 4 × strength of ACID 1).
- Add the ACID 1 or 3 a drop at a time, holding dropper bottle vertically. Swirl after each addition.
- Continue until the colour changes from pink to colourless.
- Count number of drops and read product concentration from table 2.