Using Carbon Dioxide - Agilent Technologies 6890 Series Service Manual

520 Gases
Cryogenic cooling requirements

Using carbon dioxide

WARNING Pressurized liquid CO
it exits at high pressure and low temperatures that can be dangerous to
personnel. CO
supplier for recommended safety precautions and delivery system design.
Caution Liquid CO
because the expanding liquid may form solid CO
dry ice builds up in the oven, it can seriously damage the GC.
Liquid CO
The CO
2
These contaminants could clog the expansion orifice or affect the proper
operation of the GC.
Additional requirements for the liquid CO
• The tank must have an internal dip tube or eductor tube to deliver liquid
CO
2
• The liquid CO
at a temperature of 25°C.
• Use 1/8-inch diameter heavy-wall stainless steel tubing for supply tubing.
The tubing should be between 5 to 50 feet long.
• Coil and fasten the ends of the tubing to prevent it from "whipping" if it
breaks.
• Do not install a pressure regulator on the CO
cooling would occur in the regulator instead of the oven.
• Do not use a padded tank (one to which another gas is added to increase
the pressure).
10 of 14
is a hazardous material. If CO
2
in high concentrations is toxic to humans. Consult your local
2
should not be used as a coolant for temperatures below –40°C
2
is available in high-pressure tanks containing 50 pounds of liquid.
2
should be free of particulate material, oil, and other contaminants.
instead of gas (see Figure 520-4).
must be provided to the GC at a pressure of 700 to 1,000 psi
2
Site Preparation
Agilent 6890 Gas Chromatograph Service Manual
escapes its container,
2
—dry ice—in the GC oven. If
2
system include:
2
tank, as vaporization and
2
Jun 2001