Despatch 926E Equipment Manual (C-155)Rev 2/11 - Manual (Page 15)

10

A filter installed in the line must be checked for cleanliness every 50 hours of
operation, or more often if necessary. Clean the filter in trichloroethylene and
dry thoroughly using filtered, moisture-free compressed air at low pressure.
It is important that the CO
2
solenoid valve assembly and the orifice be kept clean.
Additional Precautions

Never install CO
2
supply pipe fittings or valves of a larger internal diameter
than those used upstream [beginning at the supply cylinder(s)].

Do not use fittings which allow undue expansion or restriction of the liquid
CO
2
. This could cause the CO
2
to reach a critical point where it would
expand in the line and cause icing.

Do not use excessively long, small diameter supply hoses which might cause
the liquid to change to gas in hot areas or during intermittent cycling
conditions.

Do not meter the CO
2
through any type of valve that has a smaller I.D. than
the supply hose and CO
2
supply cylinder siphon tube. The cylinder supply
valve should be fully open during use.

It is not possible to use all of the CO
2
in a siphon-type cylinder. The ambient
temperature at the cylinder will determine the amount of CO
2
available (about
95 percent of maximum). Thus, CO
2
usage may appear to be somewhat
higher than it actually is.

Never set the temperature controller below -100

F (-73

C). Excessive
snowing occurs as you approach temperature below -100

F (-73

C) until the
temperature reaches -109

F (-78

C) which is the freezing point of CO
2
at
atmospheric pressure. At -109

F (-78

C) all discharged CO
2
could form
snow which could cause damage to the chamber and its contents and if
allowed to build up to the point of blocking off the pressure relief vent, could
cause explosion of the chamber due to available pressure from the liquid
carbon dioxide source.