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Ref. No. [UMCES] CBL 2016-015
ACT VS16-06
15
Table 2.
Summary of the mean and standard deviation of offsets between paired EXO2 DO sensor
measures and Winkler reference DO measures during laboratory trials.
Trial ID
EXO2 – Winkler DO
mean
s.d.
Observed n Possible n
L_T15_S00
-0.053
0.137
51
51
L_T15_S10
0.105
0.219
39
39
L_T15_S35
0.291
0.499
38
38
L_T04_S00
0.008
0.155
39
39
L_T04_S10
0.041
0.174
36
36
L_T04_S35
0.429
0.695
37
37
L_T30_S00
0.005
0.092
40
40
L_T30_S10
0.144
0.182
39
39
L_T30_S35
0.337
0.215
40
40
The precision of the EXO2 DO sensor was also characterized for each of the nine
temperatures and salinity trials (Table 3). Precision trials were conducted at the start of each new
tank test when conditions were most stable. Instruments were equilibrated in test tanks at indicated
temperature and salinities for 45 min then the subsequent 31 one-minute measurements were used
to estimate average tank DO (mg/L) and its variation over that interval. The absolute precision,
estimated as the standard deviation (s.d.) around the mean, ranged from 0.002 – 0.013 mg/L across
trials with an overall average of 0.004 mg/L. Relative precision, estimated as the coefficient of
variation (CV% = (s.d./mean)x100), ranged from 0.016 – 0.264 percent across trials with an
overall average of 0.062%.
Table 3.
Characterization of the precision of the Xylem EXO2 DO sensor over a range of temperatures and
salinities test conditions.
Trial ID
Temperature
Salinity
Dissolved Oxygen Reading
mg/L mean
mg/L s.d.
CV%
n
L_T15_S00
15.44
0.00
9.213
0.005
0.049
31
L_T15_S10
15.47
8.82
9.311
0.002
0.026
31
L_T15_S35
15.39
34.20
8.155
0.004
0.045
31
L_T04_S00
5.40
0.00
12.166
0.004
0.030
31
L_T04_S10
5.30
8.98
11.872
0.002
0.016
31
L_T04_S35
5.23
34.77
10.414
0.004
0.037
31
L_T30_S00
30.22
0.00
4.8
0.013
0.264
31
L_T30_S10
30.51
9.28
6.927
0.003
0.043
31
L_T30_S35
30.61
34.43
5.883
0.003
0.047
31