After recording the reading, immediately clean the sample cells with detergent and a brush. A
white film will deposit on the inside of the cells which can lead to errors in future tests if this is
not done soon after each test.
Interpretation of Results:
Results as read from the meter scale are in mg/l of sulfate ion (SO4).
If the results are near or at the maximum reading of 150 mg/l, the test should be performed again using a diluted sample.
Use the graduated cylinder to measure exactly 12.5 ml of sample water and pour into the test cell. Then add 12.5 ml of
deionized water to the same sample cell. Repeat the test using this water sample and multiply readings on the meter
scale by 2.
The presence of silica in the water sample in excess of 500 mg/l will interfere.
Refer to para 2.6.2 for shut down of the Spectrophotometer.
22.214.171.124. Turbidity Test.
Purpose of Test: To determine amount of suspended solids in a water sample.
Range: 0 to 500 FTU
Equipment Used: Found in Main Carrying Case, para 1.8, fig. 1-1
Spectrophotometer, (20), fig. 1-1
Graduated cylinder, (31), fig. 1-1
General Techniques Used: Refer to paragraphs cited below as required by procedure.
Planning the Test, para 126.96.36.199
Cleaning Glassware, para 188.8.131.52
Handling and Storing Reagents, para 184.108.40.206
Collecting Water Samples, para 220.127.116.11
Mixing, para 18.104.22.168
Using Graduated Cylinders, para 22.214.171.124
Spectrophotometer, para 126.96.36.199
High voltage used with Spectrophotometer. Misuse can cause electrical shock and damage
equipment. When operating with 115V or 220V power, make sure the power source and
equipment are in ground potential. Ensure that the power cable connections are correct for the
desired voltage power before connecting the power source.
Refer to para 2.6.2 for setup and operation of the Spectrophotometer.
Fill one of the two spectrophotometer sample cells(7, fig. 2-5) with 25 ml of sample water. Use the
graduated cylinder(31, fig. 1-1) to collect and measure the water.
Fill the other sample cell with 25 ml of clear colorless water. Use the graduated cylinder(31) to measure
the amount. This will be the test blank. If filters are available, good enough results can usually be
obtained by filtering some of the test sample. Then use the filtered water for the blank.