Refrigerated Liquid Dewars Explained - Ultratec Eclipse G3000 Operator's Manual

Refrigerated Liquid Dewars Explained

The Eclipse Low Pressure valve uses CO2 Cylinders similar to the
one pictured to the right. These are available from the local welding
supply center, and are sometimes referred to as "Dewars". Typically,
there are three valve handles, a pressure gauge and a CO2 level
indicator located on the top of the Liquid CO2 Tank. These valves
handles should be labeled as Gas/Vent, Liquid and Pressure Builder.
We will cover each of these below.
Liquid Supply
This is the source of our liquid supply of CO2. The
Eclipse CO2 supply hose is threaded onto the valve
outlet, being sure to use the appropriate sealing
washer and tighten to eliminate any leaks.
When ready to operate the Eclipse, open the Liquid
valve fully by turning counterclockwise and then
close 1/4 turn.
Gas Supply
This is used if a CO2 gas supply is utilized. As we only use the liquid
supply to operate the Eclipse, this valve is not opened
Pressure Builder
The pressure builder is a very important component in achieving the proper Eclipse operating pressure.
We can monitor this operating pressure by observing the pressure gauge located on the top of the Liquid
CO2 Tank. Ideally the operating pressure of the Liquid CO2 Tank is 300 - 330 PSI. This is achieved by
opening the pressure builder valve prior to operating the Eclipse.
TECH TIP: Building the pressure to the
proper level may take up to an hour, so it is
suggested that the Pressure Builder valve be fully
opened one to three hours before use.
NOTE: The Liquid CO2 Tank is equipped with a
pressure relief valve that is fixed to open at 350 PSI.
The pressure relief valve is in place to ensure the
internal Liquid CO2 Tank pressure does not exceed
350 PSI. As you approach the ideal operating
pressure the relief valve may open slightly and
release CO2 gas. Although this is sometimes noisy this is no cause for alarm, simply close the pressure
builder valve by turning clockwise.
NOTE: These tanks vent 1-2% daily to maintain their cold temperature. They must be stored in a well-
ventilated area to prevent dangerous CO2 accumulation.
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