Checking The Oxygen Cell Calibration - GE moisture.iq User Manual

Chapter 7. Maintenance

7.3.2 Checking the Oxygen Cell Calibration

Note: If your range of measurement is significantly below the span gas you are using, you may elect to input
the PPM O2 content of the span gas and the measured μA value instead of using the following procedure.
To perform this calibration check you must have a calibration gas with a known PPMv value and a sample
system with a calibration gas inlet valve. Proceed as follows:
Note: BHGE 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
1. Initiate flow of the calibration gas through the oxygen cell.
2. Read the PPM
incorrect, you must calculate the new span reading (x) from the following equation:
where OX = Correct PPMv for the calibration gas
c
OX = Zero value in PPMv*
0
OX = Span value in PPMv*
1
IO = Actual reading for the 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.
For example, if the calibration data for your cell is as follows:
OX = 75 PPMv = Correct PPM
c
OX = 0.050 PPM = Zero value in PPM
0 v
OX = 100 PPMv = Span value in PPMv
1
IO = 290 μA = Actual reading for the calibration gas
c
IO = 0.4238 μA = Zero value
0
Then,
The new span value (x) is 100 PPMv
page 66.
90
value. If it is correct, your oxygen cell does not need calibration. If the reading is
v
x = IO
for the calibration gas
v
v
290 +

387 μA. Enter the new value as described in "Calibrating the Probes" on
in N for a 0-100 PPM O
2 2
  IO 
OX – OX
1 c
+ -------------------------------------------------------------- -
c

OX – OX
c
  290 0.4238 
100 75 – –
------------------------------------------------------------- -
 
75 0.05 –
sensor).
2

– IO
c 0

0

= x
moisture.IQ User's Manual