Teledyne Span Standardization, Bypass, Thermal Conductivity Analyzer, Model 212R

Thermal Conductivity Analyzer Model 212R

Aftertheanalyzerstabilizesadjustthe"ZERO"controluntiltherecorder indicates the impurity concentration of the zero gas composition. Be sure that the range switch is on position #1 and that the sample path flowrate is 0.3 scfh.

NOTE if the"ZERO" or "FINE ZERO" pot runs out of adjustment and the analyzer can not be calibrated, set this pot back to mid-scale. Then use the "COURSE ZERO" pot to readjust the zero calibration as close as pos- sible to zero calibration. And last use the "ZERO" ot "FINE ZERO" pot to fine adjust the zero calibration.

3.6Span Standardization.

After the zero has been standardized, switch the selector valve to "Span", and reset the sample path flowrate to 0.3 scfh. The recorder should come to balance on, or close to, the composition of the span gas.

The analyzer is factory calibrated to make sure that the output is linear over allthreerangesofinterest. Calibrationisachievedwithmixingblocktechnique and the span setting recorded in Section 7 is derived at that time.

If the analyzer performed as described in the warm-up procedure (Section 3.4), and fails to closely approximate the composition of the span gas, there is groundsfordoubtingthespangasmixture. Becauseofthedifficultyinvolvedin obtainingpreciseanalysisofsmallamountsofimpuritiesincylindergas,and because of the ease with which the gas can be contaminated subsequent to analysis, any large error in response to the span gas should be suspect. In such a case TAI recommends that the analyzer be operated at the recommended span settinguntilthespangasisreanalyzed.

If adjustment of the span control is necessary to compensate for minor discrepancies between the recorded setting and the span gas reading, TAI suggests that the zero and span procedures be repeated until no further adjust- mentisrequired.

3.7Bypass.

Theintegral gas controlpanel features abypass flowmeterandthrottle valve that is located downstream from the input manifold (see the analyzer piping schematic in the drawing section). The bypass system can be used to speed the response of the analyzer to changes in the process. The bypass flowmeter will indicate flowrates that are a factor of ten greater than the sample path flowmeter. TAI recommends that the bypass system be used whenever the sample path is switched and particularly after using the span gas. The time required for the analyzer to stabilize on an impurity concentra- tion within the limits of Range #1, after having been exposed to a concentra- tion within the limits of Range #3, is not a function of cell response which is

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