Gas Purity - Agilent Technologies 6890 Series Service Manual

520 Gases
Gas requirements

Gas purity

Some gas suppliers furnish "instrument" or "chromatographic" purity grades
of gas that are specifically intended for chromatographic use. We recommend
these grades for use with the GC.
Generally, all gas supplies used should be in the 99.995% to 99.9995% purity
range. Only very low levels (< 0.5 ppm) of oxygen and total hydrocarbons
should be present. Oil-pumped air supplies are not recommended because
they may contain large amounts of hydrocarbons.
The addition of high-quality moisture and hydrocarbon traps immediately
after the main tank pressure regulator is highly recommended. Refer to the
next section, The gas plumbing, for more information on using traps.
Table 520-3
Carrier gases and capillary makeup gases
Helium
Nitrogen
Hydrogen
Argon/Methane
Detector support gases
Hydrogen
Air (dry)
4 of 14
Gas Purity Recommendations
99.9995%
99.9995%
99.9995%
99.9995%
99.9995%
Zero-grade or better
Site Preparation
Agilent 6890 Gas Chromatograph Service Manual
Jun 2001