Teledyne 6200A - Sulfides analyzer - Manual (Page 120)

TAI Model 6200A SO
2
Analyzer Operator Manual, 02164, Rev. G
7.8.5 SO
2
Calibration Procedure
There are two calibration procedures for 6200A such as dynamic dilution procedure using
compressed gas cylinder or using permeation tube. The procedures for multipoint calibration of
the SO
2
analyzer are specified in the Code of Federal Regulation. 1 This section applies those
general procedures to the case of the 6200A.
Calibration must be performed with a calibrator that meets all conditions specified in Subsection
2.9.2 (Q.A. Handbook). The user should be sure that all flow meters are calibrated under the
conditions of use against a reliable standard. All volumetric flow rates should be corrected to
25
o C (77 o F) and 760mm (29.92in) Hg. Make sure the calibration system can supply the range of
the concentration at a sufficient flow over the whole range of concentration that will be
encountered during calibration.
All operational adjustments to the 6200A should be completed prior to the calibration. The
following software features must be set into the desired state before calibration.
1. Single range selection. See Section 5.3.4, this manual. If the instrument will be used more
than one range, it should be calibrated separately on each applicable range.
2. Automatic temperature/pressure compensation. See Table 9-5.
3. Alternate units, make sure ppb units are selected for EPA monitoring. See Section 5.3.4.2.
The analyzer should be calibrated on the same range for monitoring. If autoranging option is
selected, the highest of the ranges will result in the most accurate calibration, and should be
used.
7.8.5.1 Calibration Using Cylinder Gas Dilution
This calibration procedure consists of diluting a gas cylinder of SO
2
standard with clean dry dilution
air.
Possible dilution system is shown in Figure 7-2. Flow controller should be capable of
maintaining constant flow rates 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 must be made of glass or Teflon and provide thorough
mixing of SO
2
gas with dilution air. Output manifold should be of a sufficient diameter to ensure
a minimum pressure drop and must be vented to create ambient pressure at the manifold. Also
must have enough flow to prevent back diffusion of ambient air into the manifold. Gas cylinder
containing 50 to 100 ppm SO
2
in air is used as the dilution source (refer Table 7-16).
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