Teledyne 6200A - Sulfides analyzer - Manual (Page 123)

TAI Model 6200A SO
2
Analyzer Operator Manual, 02164, Rev. G
Table 7-12: EPA Span Calibration Procedure
Step Number Action Comment
1. Press CAL The 6200A enters the calibrate mode from sample mode.
2. Wait 10 min Wait for readings to stabilize at span values.
3. Press SPAN If you change your mind after pressing SPAN, you can still
press EXIT here without spanning the instrument.
4. Press ENTR Pressing ENTR actually changes the calculation equations.
5. Press EXIT 6200A returns to SAMPLE mode.
The analog voltage output should measure approximately 80% of the voltage range selected.
(e.g. 4.00VDC if 0-5V output is selected.) The reading on the front panel display should be equal
to the expected SO
2
concentration entered in the procedure given in Table 7-12 above. See the
Troubleshooting Section 9.2.8 if there are problems. Also see the Calibration Quality Check
procedure Section 7.10.
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 SO
2
response.
Plot the analyzer SO
2
response 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 SO
2
calibration, 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.
7.8.5.2 Calibration Using Dynamic Permeation Dilution
The procedure for multipoint calibration of an SO
2
analyzer by an SO
2
permeation system are
specified in Code of Federal Regulations. 1
Possible dilution system is shown in Figure 7-3. Permeation chamber temperature must be
maintained within ±0.1
o C of accuracy. Should allow a minimum of 24 hours of temperature
equilibrium period after power up of the temperature controller. Flow controllers should be
capable of maintaining constant flow rate to within ±1%. Flowmeters capable of measuring flow
rates to within ±2% are required. NIST-traceable soap bubble flowmeter or wet-test meter are
suitable for flow determination. Mixing chamber is made of glass and should provide thorough
mixing of SO
2
gas with dilution air. Output manifold should be sufficient diameter to ensure a
minimum pressure drop and must be vented to create ambient pressure at the manifold.
Permeation tube traceability is established by referencing the permeation device to a NIST-SRM
(refer to Table 7-16).
7-16