Hach LDO Manuel D'utilisation page 11

Enter a salinity correction value
Dissolved oxygen measurements in saline samples can show an apparent DO value that is very
different from the actual DO value. To correct for the influence of dissolved salts in a sample, enter a
salinity correction factor.
Note: If the presence or amount of salinity in the process is unknown, consult with the treatment facility engineering
staff.
1. Use a conductivity meter to measure the conductivity of the sample in mS/cm at a reference
temperature of 20 °C (68 °F).
2. Use Table 1 to estimate the salinity correction factor in parts per thousand (‰) saturation.
Note: The chloride ion concentration, in g/kg is equal to the chlorinity of the sample. Salinity is calculated with
the formula: Salinity = 1.80655 × chlorinity.
Salinity can be calculated with the relationship in section 2520 B of Standard Methods for the
Examination of Water and Wastewater.
3. Go to MENU>SENSOR SETUP>[Select Sensor]>CONFIGURE>SALINITY.
4. Enter the salinity correction factor and confirm.
Table 1 Salinity saturation (‰) per conductivity value (mS/cm)
mS/cm ‰
5 3
6 4
7 4
8 5
9 6
10 6
11 7
12 8
13 8
14 9
15 10
Configure linear output on the controller
Linear outputs send probe data back to the facility PLC, SCADA or other data collection system.
1. Go to the controller output setup menu.
Option Description
sc200 Go to MENU>SETTINGS>sc200 SETUP>OUTPUT SETUP>[Select Output]>SET FUNCTION.
2
Standard Methods for the Examiniation of Water and Wastewater, 20th Edition. Editors Lenore
S. Clesceri, Arnold E. Greenberg and Andrew D. Eaton, p. 2-48-2-29 (1998). The relationship
between Chlorinity and Oxygen Solubitity is provided in the same reference in 4500-O:I p. 4-131.
2
,
mS/cm ‰
16 10
17 11
18 12
19 13
20 13
21 14
22 15
23 15
24 17
25 17
26 18
mS/cm ‰
27 18
28 19
29 20
30 21
31 22
32 22
33 23
34 24
35 25
36 25
37 26
mS/cm ‰
38 27
39 28
40 29
42 30
44 32
46 33
48 35
50 37
52 38
54 40
English 11