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Teledyne Analytical Instruments
12
Thermal Conductivity Analyzer Model 212R
2.3.7 Vent Lines.
The sample path, reference path, and an integral bypass system vent from
separate ports at the rear of the analyzer. Wherever possible, TAI recommends
that the gases be permitted to vent directly to the atmosphere. If it is necessary
to carry these gases to a remote area the following precautions must be ob-
served when installing the vent lines:
1) The vent lines must be 1/4" tubing or larger so that no back pressure
resulting from restricted flow is experienced by the measuring cell.
2) The sample and reference paths must vent into an area that experi-
ences the same ambient pressure conditions.
3) The ambient pressure at the vent location should undergo no more
than normal barometric pressure fluctuations.
4) The vent lines must be installed so that water and dust cannot accu-
mulate in them.
A pressure differential existing at the cell between the reference and sample
will result in a corresponding change in output signal. The reference and sample
path flowmeters are located upstream from the cell so that both cell paths can
vent directly to atmosphere. The random bounce of the floats in the flowmeters,
when located downstream from the measuring cell, can produce up to 5% noise
on the output signal.
3.0 STARTUP
3.1 Preliminary.
The following preliminary steps should be accomplished before apply-
ing power or starting gas flow.
1. Check the integral gas control panel and be sure that all valves are
closed (fully cw). Do not jam the sample, reference, and bypass
metering valves.
2. Place the “RANGE” switch on the #2 position.
3. Set the “SPAN” control to the reading recorded in Section 7 of the
manual.