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Reference Manual
00809-0100-3565
A
Verify linearity
This procedure describes how to verify linearity between turbidity and TSS.
Procedure
1. Collect a sample of the process liquid.
2. Filter a portion of the sample to obtain at least 5 L of dilution liquid.
3. Measure the total suspended solids (TSS) in the sample obtained in
4. Dilute the sample from
Dilution factor
Volume of stock, mL
1.00
--
0.9
900
0.7
700
0.5
500
0.3
300
0.1
100
5. Plot the data obtained in
6. Locate two points (P1 and P2) on the line separated as much as possible. Read the
Rosemount T56
You may need 10 L or more if you use the Rosemount
turbidity. If you uses a laboratory turbidmeter, you will need less volume. The
Rosemount Clarity II requires about 500 mL for the measurement; laboratory
turbidmeters require 50 mL or less. Verify that the turbidity of the sample is less
than 200 NTU. Store in a clean bottle.
The filtrate is needed to dilute the sample in subsequent steps. Verify that the
turbidity of the dilution water is low. If filtering the sample is impractical, use
deionized water for dilution.
Thoroughly mix the sample before withdrawing liquid.
A magnetic stirrer is best, but inverting the sample repeatedly for about a minute
works too. Avoid violent shaking or mixing. Refer to any standard reference work on
water and wastewater testing for the procedure for determining TSS.
Step 1
See the table for recommended volumes. Measure TSS and turbidity for each
dilution. For lower TSS values, use a larger volume of sample.
Final volume, mL
--
1000
1000
1000
1000
1000
Fit the best straight line to the data.
ppm and NTU value for each point and enter these into the transmitter.
by a factor of 0.9, 0.7, 0.5, 0.3, and 0.1.
Volume for
Rosemount Clarity II,
mL
500
500
500
500
500
500
Step
4, with turbidity on the Y-axis and TSS on the X-axis.
Verify linearity
July 2020
™
Clarity II for measuring
Step
1.
Volume for TSS, mL
50 - 250
50 - 250
50 - 250
50 - 250
50 - 250
50 - 250
59
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