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Teledyne API Model 200A NO
X
Analyzer Instruction Manual, 02246, Rev. G, DCN 5247
Plot the analyzer NO and NO
x
responses versus the corresponding calculated concentrations to
obtain the calibration relationships. Determine the straight line of best fit (y = mx + b)
determined by the method of least squares.
After the best-fit line has been drawn for the NO and the NO
x
calibrations, determine whether
the analyzer response is linear. To be considered linear, no calibration point should differ from
the best-fit line by more than 2% of full scale.
7.8.5.3 GPT - NO
2
Calibration Procedure
The M200A computes the NO
2
concentration by subtracting the NO from the NO
x
concentration.
Unlike analog instruments, this difference is calculated by the M200A's internal computer
software. It is extremely unlikely that the NO
2
concentration will be in error. Therefore this
procedure is a confirmation that the NO
2
subtraction algorithm in the computer is operating
correctly.
NOTE
During this procedure do not make any adjustments to the instrument.
1.
Generate an NO concentration near 90% of the URL. Dilution air and O
3
generator air
flows should be the same as used in the calculation of specified conditions of the dynamic
parameter according to Section 7.8.4. Sample this NO concentration until the NO and NO
x
responses stabilize. Record the NO and NO
x
concentrations.
2.
Turn on and adjust the O
3
generator in the calibrator to produce sufficient O
3
to decrease
the NO concentration to about 10% of full scale. This will be equivalent to 80% of the URL
of the NO
2
channel. After the analyzer responses stabilize, record the resultant NO, NO
x
, and
NO
2
concentrations.
MOLY CONVERTER EFFICIENCY
IF THE NO
x
READING SHOULD DROP TO LESS THAN 96% OF ITS STARTING
VALUE DURING THIS STEP, IT INDICATES THE MOLY CONVERTER IS IN NEED
OF TROUBLESHOOTING OR REPLACEMENT. SEE SECTION 7.8.6 FOR FURTHER
DETAILS.
3.
While maintaining all other conditions, adjust the ozone generator to obtain several other
concentrations of NO
2
evenly spaced between the 80% URL point and the zero point. Record
the NO, NO
x
, and NO
2
concentrations for each additional point.
7-24
PRINTED DOCUMENTS ARE UNCONTROLLED