Checking The Oxygen Cell Calibration - GE Moisture Image 1 Series Service Manual

Checking the Oxygen
Cell Calibration
Troubleshooting and Maintenance
Note: If your operational range of measurement is significantly
below the span gas you are using, you may elect to input the
PPM O content of the span gas and the measured µA value
2
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
100 PPM O sensor).
2
1. Run the calibration gas through the oxygen cell.
2. Read the PPM value. If it is correct your oxygen cell does not
v
need calibration. If the reading is incorrect, you must calculate the
new span reading (x). Solve the following equation for x:
x = IO
c
where OX = Correct PPMv for calibration gas
c
OX = Zero value in PPMv*
0
OX = Span value in PPMv*
1
IO = Actual reading for calibration gas in µA
c
IO = Zero value in µA*
0
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 = 75 PPMv = Correct PPM
c
OX = 0.050 PPM
0
OX = 100 PPMv = Span value in PPMv
1
IO = 290 µA = Actual reading for calibration gas
c
IO = 0.4238 µA = Zero value
0
( ) IO (
OX – OX – IO
1 c c
+ -------------------------------------------------------------- -
( )
OX – OX
c 0
for cal gas
v
= Zero value in PPM
v
June 2003
in N for a 0-
2 2
)
0
v
2-23