Despatch 926E Equipment Manual (C-155)Rev 2/11 - Manual (Page 14)

9
Installation of Carbon Dioxide
Before purchasing or installing CO
2
gas supplies, insure that the test chamber is the
correct model to use CO
2
(High - 70 Kg/cm2 or 1,000 PSI or Low - 21 Kg/cm2 or 300
PSI) and that the desired low temperature can be reached by use of this gas. The
following special CO
2
requirements must be met:

The liquid CO
2
should be furnished by a reputable source.

The liquid CO
2
cylinder must be a siphon-type. Syphon tank will have a red
neck.

The interior of the cylinder must be clean and absolutely dry before being
filled by the supplier.

Use of welding grade CO
2
offers no assurance of trouble- free operation.
The internal condition of the cylinder and its previous use are more important
than the quality of the CO
2
.

Never fully exhaust the cylinder after use or leave a cylinder which is to be
returned to the supplier with the valve open. This will permit moisture or
other contaminants to enter the cylinder and cause serious problems when
the cylinder is reused later. If a cylinder is returned to the supplier without a
positive pressure, it must be purged with dry nitrogen by the supplier before
filling.
Other important factors are as follows:

The interior of the liquid CO
2
pipe, tubing, hose and fittings
used between the supply
cylinder and the solenoid input
valve of the temperature
chamber must be kept clean and
free of moisture at all times. Any moisture will turn to ice as the liquid CO
2
flows through the lines; the ice can then lodge on the solenoid valve seat or
plug the orifice of the valve and cause system malfunction.

Any low-pressure CO
2
connecting hoses between the supply cylinder(s) and
the chamber input valve should be kept as short as possible and should be
insulated.

If the connecting hose is removed often or has been stored for a period of
time, the line and fittings must be examined for presence of chips, rust or any
foreign substance which can jam the inlet valve or plug the valve orifice.
WARNING: Nitrogen and carbon dioxide
gases can cause asphyxiation and death if
used in confined, poorly-ventilated areas.
Nitrogen and carbon dioxide as liquid or
cold gases can cause freeze burns of the
eyes and skin.