EPA Protocol Calibration Model 200E Instruction Manual
concentration to the NO concentration to get the NO
X
concentration for calibration.
Calculate the exact NO and NO
X
concentrations as follows:
F
]
[NO x
F
=
]
[NO
T
STD
NO
OUT
Eq 8-8
Enter the respective concentrations using the procedure in Section 7.2. The expected span
concentrations need not be re-entered each time a calibration is performed unless they are
changed.
• Enter the expected NO
X
and NO span gas concentrations:
• Sample the generated concentration until the NO and the NO
X
responses have
stabilized.
• Span the instrument by the following the same method as Sections 7.2, 7.4 or 7.5:
The analog voltage output should measure 80% of the voltage range selected. (e.g.
4.00 VDC if 0-5V output is selected.) The readings on the front panel display should be
equal to the expected NO and NO
X
concentrations entered in the procedure given in
Sections 7.2, 7.4 or 7.5 above. See the Troubleshooting Chapter 11 if there are problems.
Also see the Calibration Quality Check procedure Section 7.9.
After the zero and the 80% URL points have been set, generate five approximately evenly
spaced calibration points between zero and 80% URL without further adjustment to the
instrument. Allow the instrument to sample these intermediate concentrations for about 10
minutes each and record the instrument NO and NO
X
responses.
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.
8.3.3. GPT NO
2
Calibration
The M200E computes the NO
2
concentration by subtracting the NO from the NO
X
concentration. Unlike analog instruments, this difference is calculated by the M200E'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
Do not make any adjustments to the instrument during this procedure.
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 8.2. Sample this NO concentration until the NO and NO
X
responses stabilize. Record the NO and NO
x
concentrations.
134 044100102 Rev A
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