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Jun 2001
Site Preparation
Agilent 6890 Gas Chromatograph Service Manual
Gases 520
The gas plumbing
Be generous when cutting tubing for local supply lines—a coil of flexible tubing
between the supply and the instrument lets you move the GC without moving
the gas supply. Take this extra length into account when choosing the tubing
diameter.
Two-stage pressure regulators
To eliminate pressure surges, use a two-stage regulator with each gas tank.
Stainless steel, diaphragm-type regulators are recommended.
Figure 520-2 Two-stage pressure regulator
The type of regulator you use depends upon gas type and supplier. The
Chemical Analysis Consumables and Accessories catalog contains
information to help you identify the correct regulator, as determined by the
Compressed Gas Association (CGA). Agilent Technologies offers pressure-
regulator kits that contain all the materials needed to install regulators
properly.
Pressure regulator-gas supply tubing connections
The pipe-thread connection between the pressure regulator outlet and the
fitting to which you connect the gas tubing must be sealed with Teflon tape.
Instrument grade Teflon tape (part no. 0460-1266), from which volatiles have
been removed, is recommended for all fittings. Do not use pipe dope to seal
the threads; it contains volatile materials that will contaminate the tubing.
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