67
INZ-TN2ZRE-E
(2) Method for span calibration by check gas
The method for span calibration by use of check gas (give in 2) is explained. Since span calibra-
tion has an error of calibration curve, preset a calibration indication on the calibration curve graph
attached to this analyzer for indirect calibration.
1) The following calibration curve graph is attached to the test results for the product.
In graph, the calibration curve by the scale gas (that is similar to plant gas and determines
scales of this analyzer) and the calibration curve by the check gas that is adjusted by the
scale gas (gas of simple composition of N
2
balance gas to facilitate the analyzer check) are
drawn.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1% CO
2
1.0V
0.9
0.89V
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.95% CO
2
0.89% CO
2
Calibration curve by scale gas
(composition of plant gases)
Output
Calibration curve by check
gas (N
2
balance gas)
* When supplying check
gases to instruments
adjusted by the scale gas
composition.
Measured gas concentration
Calibration curve graph attached to the analyzer
2) When using 0.95% CO
2
and remainder N
2
(check gas) as calibration gas, in graph, a point
of 0.95% on X-axis should be stretched to upward, draw a line toward Y-axis from the
cross point with the check gas calibration curve. From the cross point with calibration
curve on the scale gas composition, 0.89% or equivalent values can be obtained.
3) Set this point (0.89%) to the span calibration concentration of the calibration concentration
set value.
4) Supply 0.95% check gas to perform span calibration. It is calibrated to 0.89%.
Measurement suited to actual plants can be performed by this error correction of calibra-
tion curve.