Ocean Optics OOISensors - Manual (Page 52)

3: Oxygen Sensors
T (ºC)
T*
(T/100K) Mole Fraction of oxygen in
water at 1 atmosphere pO2 Weight Fraction (ppm) at
1 atmosphere pO2 (pure O2) Weight Fraction (ppm) at 0.209476
atmospheres pO2 (Air)
5 2.7815 3.46024E-05 61.46203583 12.87482142
10 2.8315 3.06991E-05 54.52891411 11.42249881
15 2.8815 2.75552E-05 48.94460474 10.25272002
20 2.9315 2.50049E-05 44.41468119 9.303809756
25 2.9815 2.29245E-05 40.71933198 8.529722785
30 3.0315 2.12205E-05 37.69265242 7.895706058
35 3.0815 1.98218E-05 35.20817214 7.375267068
40 3.1315 1.86735E-05 33.16861329 6.948028438
Temperature
Temperature affects the fluorescence decay time, the fluorescence intensity, and the collisional frequency
of the oxygen molecules with the fluorophore. This, therefore, affects the diffusion coefficient of oxygen.
Temperature also affects the solubility of oxygen in samples. The net effect of temperature fluctuations is
seen as a change in the calibration slope:
Fiber optical oxygen probe temperature
test
(constant O
2
ratio, varied temp.)
y
0
= 1.3522x + 1.0049
y
10
= 1.5471x + 1.0084
y
40
= 2.4684x + 1.0301
y
30
= 2.0768x + 1.0206
y
20
= 1.7818x + 1.0134
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
0 0.2 0.4 0.6 0.8 1
O
2
/(O
2
+N
2
)
V
0
/V
0
10
20
30
40
Linear (0)
Linear (10)
Linear (40)
Linear (30)
Linear (20)
Decreasing
temperature
Calibration Slope with Temperature Fluctuations
42 FOXY-AL300-000-02-0207