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OPERATING INSTRUCTIONS M400E Ozone Analyzer Operator’s Manual
When F
d
has been adjusted and R has been calculated, assay the diluted concentration with the photometer and
then compare the diluted assay (A
2
) with the original undiluted assay (A
1
) by calculating the percentage of
linearity error (E) according to the following equation.
Equation 10-2
100
A
)R/A(A
E
1
21
×=
This linearity error must be <5% in magnitude and should be <3% for a well-performing system.
NOTE
The result is not the true linearity error because it includes possible instrument errors in the flow
measurements. This test technique should only be used as an indicator
If the linearity error is >5% or is greater than you expect it to be, check and verify the accuracy of the flow
dilution carefully before assuming that the photometer is inaccurate. The test should be carried out several
times at various dilution ratios, and an averaging technique should be used to determine the final result.
If the linearity error is excessive and cannot be attributed to flow measurement inaccuracy, check the
photometer system for:
Dirty or contaminated cell, lines or manifold.
Inadequate "conditioning" of the system.
Leaking of two-way valve or other system components.
Contaminated zero-air.
Non-linear detectors in the photometer.
Faulty electronics in the photometer.
178 04315 Rev. C1