User Manual

<Appendix 4 For DO (Dissolved Oxygen)>
App.4-1
IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
Appendix 4 For DO (Dissolved Oxygen)
n Dissolved oxygen
Dissolvedoxygenmeanstheoxygendissolvedinwater.
Itsconcentrationisexpressedastheamountofoxygenperunitvolumeofwater(mg/Lorppm).
Thesolubilityofoxygeninwatervariesdependingonwatertemperature,salinity,atmospheric
pressure, etc.
The sensors used in FLXA21 use the membrane electrode method to measure the dissolved
oxygen.
Two methods are available: galvanic cell method and polarographic method.
n Compensation
There are three compensation methods for FLXA21: temperature compensation, salinity
compensation, and process pressure compensation.
Salinity and temperature compensations meet ISO 5814 (see Table 1).
There is no need to change the setting for normal usage.
Usethesalinitycompensationwhenmeasuringasolutioncontainingsalt(seeSection13.2.4).
For operation at high altitude, adjust the pressure value for the process pressure compensation
(see Section 13.2.5).
Table 1 Solubility of oxygen in water as a function of temperature and salinity
Temperature
(°C)
Solubility of oxygen in water in
equilibrium with air at 101.325 kPa
(mg/l)
Correction to be subtracted for each degree of salinity
expressed in g/kg of total salts (NaCl) in water
(mg/l)
0 14.62 0.0875
1 14.22 0.0843
2 13.83 0.0818
3 13.46 0.0789
4 13.11 0.0760
5 12.77 0.0739
6 12.45 0.0714
7 12.14 0.0693
8 11.84 0.0671
9 11.56 0.0650
10 11.29 0.0632
11 11.03 0.0614
12 10.78 0.0593
13 10.54 0.0582
14 10.31 0.0561
15 10.08 0.0545
16 9.87 0.0532
17 9.66 0.0514
18 9.47 0.0500
19 9.28 0.0489
20 9.09 0.0475
21 8.91 0.0464
22 8.74 0.0453
23 8.58 0.0443
24 8.42 0.0432
25 8.26 0.0421
26 8.11 0.0407
27 7.97 0.0400
28 7.83 0.0389
29 7.69 0.0382
30 7.56 0.0371
ISO 5814:1990(E)
App.
DO