Thermal Conductivity Analyzer | Model 212R |
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The reference and sample flowrates should be checked daily. The instru- ment is somewhat flow sensitive. Operating on Range #1 a change in flowrate of
0.1scfh will cause a corresponding change in sensitivity of from 1 to 20% of scale. On the coarser ranges, the change in sensitivity would be undetectable.
The sample path flowrate should be maintained at 0.3 scfh, the reference path flowrate at 0.1 scfh, and the bypass flowmeter float should be slightly above the bottom of the indicator glass.
4.2Supporting Gas Supplies.
Supportingcylindergassuppliesshouldbecheckedfrequentlyonaroutine basis with particular attention focused on the reference gas. A spare cylinder of reference gas should be available at all times. When the cylinder pressure drops below 100 psig the reference supply should be replaced as the operation of the regulatorisquestionableatpressuresbelowthispoint.
When replacing supply cylinders, be sure to bleed the gas through the cylinder valve while installing the pressure regulator (see Section 2.3.4). It is also advisable to check the connections with soap water whenever a supply cylinder is changed.
4.3Standardization.
Theanalyzermustbecompletelyrestandardizedwheneverthereference gassupplyisreplaced. Barringunforeseendifficultieswiththeanalyzer,re- standardizationshouldnotbenecessarybetweenreferencecylinderreplacement periodsiftheanalyzerisruncontinuously. Iftheanalyzerisshutdownforlong period of time use the startup procedure (in its entirety) when operation is to be resumed.
NOTE: TAI strongly recommends that the analyzer run con- tinuously with gas flowing in both the sample and reference paths. During inactive periods arrange the input manifold so that zero gas is flowing. Gas sup- plies can be conserved by reducing the sample and reference path flowrates to less than 0.1 scfh and closing off the bypass flow completely.
16 | Teledyne Analytical Instruments |
