Xylem WQ-FDO OPTICAL DISSOLVED OXYGEN TRANSMITTER User Manual
Page 10
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equations done by R.F. Weiss in 1970 and are generally considered to be a
standard. These table entries will need to be corrected for salinity in the same way
as the concentration above. Find the correction value from Tables 7.1 to 7.4.
Multiply the oxygen solubility from tables 6.1 – 6.4 by the correction value to
obtain the adjusted solubility.
An equation can also be used, which is based on the work done by Weiss. To find
the solubility, use the following equation which has been corrected for altitude and
salinity:
Solubility of Oxygen in Water (100% Saturation):
S
c
= EXP(A + B*100/(T+273.15) + C*LN((T+273.15)/100) + D*(T+273.15)/100
+ S*(E + F*(T+273.15)/100 + G*((T+273.15)/100)^2))*H*P
a
Where:
S
c
= Solubility of O
2
in mg/L corrected for salinity, temperature and pressure
T = Temperature in ºC
S = Salinity in PSS
P
a
= Atmospheric pressure in mbar
And:
A = -173.4292
B = 249.6339
C = 143.3483
D = -21.8492
E = -0.033096
F = 0.014259
G = -0.001700
H = 0.00140934
Percent Oxygen Saturation:
S = (C / S
c
) * 100
Where:
S = Oxygen percent saturation (%) of water sample
C = Concentration adjusted for salinity as calculated above
Sc = Corrected solubility as calculated above, or from tables