Teledyne 238 - Thermal conductivity analyzer - Manual (Page 15)

3-1 Teledyne Analytical Instruments
Thermal Conductivity Analyzer Operation 3
Operation
3. 1 Preliminary
• Check to see that all gases have been connected to the proper
ports of the analyzer and that all gas connection lines are leak-
free.
• Check to see that the power and signal wiring has been properly
installed.
• Check to see that the fuses in the analyzer are intact.
• Check to see that all PC Boards are intact and securely plugged
in.
• Turn the recorder and power switches to the “ON” position.
3.2 Gas Flowrate
Start the REFERENCE gas flow, and adjust the flowrate to approxi-
mately 0.08 SCFH (40 cc/min.)
Start ZERO gas through the sample path of the analyzer, and adjust
the flowrate to approximately 0.3 SCFH (150 cc/min).
See Section 2.6 for additional flowrate information for gases lighter or
heavier than air.
Allow the analyzer to run with zero and reference gas flowing for
several hours before attempting calibration. This will permit the cell to come
to thermal equilibrium.
3.3 Zero Standardization
After the necessary temperature stabilization period, the analyzer can
be zero-standardized as follows:
NOTE: Before zero-standardization of the analyzer is possible, and while
the power is off, the mechanical zero of the meter must be
checked. If the pointer does not rest at zero with the power off,
then adjust the slotted screw found at a low center position of the
meter face to correct. DO NOT allow this screw to be readjusted
after the zero-standardization has been performed. No mechanical
zero is used with digital meters.