Teledyne 6750 - Total Organic Carbon analyzers - Manual (Page 25)

Total Organic Carbon Analyzer Theory of Operation
Teledyne Analytical Instruments 13
Figure 2-7: Sample Handling TOC-True
2.4.2.2 G AS P HASE S AMPLE H ANDLING
Referencing Figure 3-5 and “As Built” drawings in the Appendix, a
carrier gas of (99.8%) pure oxygen or CO
2
and hydrocarbon-free air is
required. Erroneous TOC analysis will occur if the carrier gas has these
impurities, since both CO
2
and Hydrocarbon gases will contribute a
higher TOC value to the analysis than is actually present in the sample.
An Oxygen Generator (P/N ST200025) is available from Teledyne
that separates oxygen from the ambient air. It is a pressure swing
absorption PSA device requiring only electricity only to operate. Also
available from Teledyne is an Instrument Air Purifier (P/N ST200019).
This device can supply the oxygen demands of the instrument using
facility instrument air.
Facility carrier gas is introduced to the analyzer, regulated at 15± 2
psi, and then controlled by an internal mass flow controller (MFC-1) to
precisely control the flow rate of the carrier.
Note: Precise carrier gas flow control is mandatory for accurate