PROBE BUDDY – USER MANUAL
Page 18 of 27
UPC_MAN013_R7
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PROBE BUDDY’s sensor millivolt output simulates an in-situ zirconia sensor. The T/C output
simulates the integrated temperature T/C in the oxygen sensor. The result of the calculation is
dew point in °F.
DP = (4238.7/(9.55731-LOG10(PH2)+(mV-1267.8)/(0.05512*Tr)))-460
mV = millivolts
PH2 = partial pressure of hydrogen (default = .40)
TR = Temp Rankin
DP = dew point °F (or °C if converted)
Test Case:
H2%
Temp F Temp R
mV
DewF
DewC
0.40 1652.00 2111.67
1100 37.873
3.263
0.40 1652.00 2111.67
1000 93.755 34.308
0.40 1472.00 1931.67
900 192.020 88.900
H2%
Temp F Temp R
mV
DewF
DewC
0.30 1652.00 2111.67
1100 30.673 -0.737
0.30 1652.00 2111.67
1000 84.862 29.368
0.30 1472.00 1931.67
900 179.725 82.070
The displayed dew point value is rounded up to XXX.X. This result in Fahrenheit is converted
to Celsius, if Celsius is selected as the temperature scale.
The displayed range of values is -99.9°F (-73.3°C) to 212°F (100°C).
This calculation is only valid for an endothermic atmosphere in a state of equilibrium. The
equation is not accurate for a dew point of exothermic gases or other applications.
Oxygen Formula
The oxygen calculation is based on the sensor millivolt output of an in-situ zirconia sensor with
a 20.9% reference oxygen and an integral temperature sensor. There are no adjustments to
the calculation.
%𝑂𝑂2 = 0.2095/𝑒𝑒
(
𝐸𝐸𝐸𝐸
0.0215𝑇𝑇𝑇𝑇)
Where: Tk = Sensor temperature in Kelvin
Eo = Sensor millivolt output
e = natural log
Test Case:
Temp = 1425°C = 1698.15K
Eo = 85mV
O2 = 0.02042
2.042%
The displayed percent oxygen value is rounded to XX.XX. As the oxygen value drops below
the least significate digit (00.01%), the display will automatically shift to X.X PPM. No
additional adjustment factors are required. Zirconia sensors can read very low oxygen
