1. Firstly prepare standard color: In a group of 25 ml colorimetric tube, take fluid according to table 5
No. | Solution consumption （mL） | Equivalent to residual chlorine inn water sample （mg/L） | |||
Concentrated solution of potassium dichromate | Diluted solution of potassium dichromate | Copper sulfate solution | Distilled water | ||
1 | — | 0.52 | — | 24.48 | 0.02 |
2 | — | 0.8 | — | 24.2 | 0.03 |
3 | — | 1.07 | — | 23.93 | 0.04 |
4 | — | 1.37 | 0.1 | 23.53 | 0.05 |
5 | — | 1.87 | 0.3 | 22.83 | 0.07 |
6 | — | 2.17 | 0.38 | 22.45 | 0.08 |
7 | — | 2.25 | 0.43 | 22.32 | 0.09 |
8 | — | 2.50 | 0.45 | 22.05 | 0.10 |
9 | 0.05 | — | 0.50 | 24.00 | 0.20 |
10 | 0.75 | — | 0.50 | 23.75 | 0.30 |
11 | 0.95 | — | 0.50 | 23.55 | 0.40 |
12 | 1.28 | — | 0.50 | 23.22 | 0.60 |
13 | 1.45 | — | 0.50 | 23.05 | 0.70 |
14 | 1.68 | — | 0.50 | 22.82 | 0.90 |
15 | 1.80 | — | 0.50 | 22.70 | 1.00 |
2. Measurement of water sample Inject 25mL water sample in 25 mL colorimetric tube, add 0.25 mL Ellms-Hauser solution hydrochloric acid solution, and shake it well, place it after 5 minutes, then compare the color with standard color.
