GE Moisture Image 1 Series, Service Manual, Page: 55 / 107

Troubleshooting and Maintenance 2-23
June 2003
Checking the Oxygen
Cell Calibration
Note: If your operational range of measurement is significantly
below the span gas you are using, you may elect to input the
PPM O
2
content of the span gas and the measured µA value
as an alternative to the following procedure.
To perform this part of calibration you must have a calibration gas
with a known PPMv value and a calibration gas inlet valve.
Note: GE Panametrics recommends a span calibration gas be 80-
100% of the span of the sensor’s overall range in a
background of nitrogen (e.g., 80-100 PPM O
2
in N
2
for a 0-
100 PPM O
2
sensor).
1. Run the calibration gas through the oxygen cell.
2. Read the PPM
v
value. If it is correct your oxygen cell does not
need calibration. If the reading is incorrect, you must calculate the
new span reading (x). Solve the following equation for x:
where OX
c
= Correct PPMv for calibration gas
OX
0
= Zero value in PPMv*
OX
1
= Span value in PPMv*
IO
c
= Actual reading for calibration gas in µA
IO
0
= Zero value in µA*
x = New span reading in µA
*See the Calibration Data Sheet for the oxygen cell to obtain the
necessary zero and span values.
Example:
If the calibration data for your cell is as follows:
OX
c
= 75 PPMv = Correct PPM
v
for cal gas
OX
0
= 0.050 PPM
v
= Zero value in PPM
v
OX
1
= 100 PPMv = Span value in PPMv
IO
c
= 290 µA = Actual reading for calibration gas
IO
0
= 0.4238 µA = Zero value
x IO
c
OX
1
OX
c
–
( )
IO
c
IO
0
–
( )
OX
c
OX
0
–
( )
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