Teledyne API Model 200A NOX Analyzer Instruction Manual, 02246, Rev. G, DCN 5247
Plot the analyzer NO and NOx 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 NOx 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 - NO2 Calibration Procedure
The M200A computes the NO2 concentration by subtracting the NO from the NOx concentration.
Unlike analog instruments, this difference is calculated by the M200A's internal computer
software. It is extremely unlikely that the NO2 concentration will be in error. Therefore this
procedure is a confirmation that the NO2 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 O3 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 NOx
responses stabilize. Record the NO and NOx concentrations.
2. Turn on and adjust the O3 generator in the calibrator to produce sufficient O3 to decrease
the NO concentration to about 10% of full scale. This will be equivalent to 80% of the URL
of the NO2 channel. After the analyzer responses stabilize, record the resultant NO, NOx, and
NO2 concentrations.
MOLY CONVERTER EFFICIENCY
IF THE NOx 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 NO2 evenly spaced between the 80% URL point and the zero point. Record
the NO, NOx, and NO2 concentrations for each additional point.
7-24
PRINTED DOCUMENTS ARE UNCONTROLLED