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Teledyne Analytical Instruments
13
Thermal Conductivity Analyzer Model 212R
4. Determine what the sample pressure is and set the output pressure of
the cylinder gas supplies to agree with the sample pressure. This
procedure, although not absolutely necessary, will minimize flow
adjustments when the sample path is switched to the various inputs.
5. Turn the analyzer and recorder power switches to “ON”.
3.2 Reference Gas Flow.
Open the reference gas throttle valve adjacent to the “Ref. Flow” meter,
and set the valve for an indicated flowrate of between 0.1 and 0.3 scfh. Since
the actual setting is not critical, TAI suggests that the flow be set at 0.1 scfh to
conserve the reference gas supply.
3.3 Zero Gas Flow.
Open the “ZERO” valve (ccw until a release in tension is felt), and adjust
the throttle valve to the right of the “SAMPLE FLOW’ flowmeter for an indi-
cated flowrate of 0.3 scfh.
3.4 Warmup.
A warm-up period of twenty-four (24) hours is recommended to stabilize
the interior of the analyzer at the control temperature level. Until the measuring
cell temperature has equilibrated with the control temperature, the output signal
will drift.
During the warmup period, check the recorder periodically. As the drift
rate decreases, increase the sensitivity by moving the range switch towards
Range #1.
IMPORTANT:
The zero control will have little or no effect until Range #1 is reached. If the
recorder is off scale towards electrical zero (negative signal) after 24 hours of
running on zero gas, use the procedure outlined in Section 6.2. The drift rate will
decrease exponentially. When the rate of change slows to approximately 1%
per hour, place the “RANGE” switch on position #1 and readjust the “ZERO”
control so that the recorder is reading midscale. Do not attempt to calibrate the
analyzer until the recorder indication stabilizes.
3.5 Zero Standardization.