Labconco FreeZone 6 Liter Benchtop Freeze Dry Systems 77520 Series - Manual (Page 25)

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Chapter 4: Using Your Freeze Dryer
Product Service: Domestic 1-800-522-7658, International 816-333-8811
Manual Start-Up
To manually run the freeze dry process, press the
REFRIGERATION MAN switch. This will start the refrigeration
system. The green LED above the switch will illuminate. When
the collector temperature reaches –40°C, the vacuum pump may be
started by pressing the VACUUM switch. The Temperature and
Vacuum Graphs will indicate collector temperature and system
vacuum. The LCD display will show the actual temperature of the
collector. When the vacuum in the system is above 5 mBar the
vacuum display will indicate “HI.” At 5 mBar and below, the
display will show the actual vacuum.
When the system vacuum is between 0.450 and 0.133 mBar, the
lower green vacuum graph LED will flash. When the system
vacuum level is <0.133 mBar, the green LED will be lit steadily
indicating that samples may be added.
Setting the Operating Vacuum
Level
The vacuum level may be set by the user to optimize the freeze dry
process. Normally, the sublimation rate will increase if there is
less vacuum (a higher pressure) in the Freeze Dryer. A good
starting place is to set the vacuum so its level is equivalent to about
10°C colder than the eutectic or collapse temperature of the
sample. Adjustments to the vacuum level must be made for
various freeze drying conditions. Factors that must be considered
are whether the sample is freeze dried on heated shelves or in
glassware attached to manifold valves, the volatility of the sample
itself, the size of the sample and the heat energy supplied to the
sample.
When the vacuum control is set to operate at less vacuum, the ice
holding capacity of the collector may be decreased. This can be
improved by installing a baffle in the collector. See Appendix D
Freeze Dryer Accessories for the baffle part number. Position the
baffle so it rests on the top of the collector coil. The arrow should
point toward the front.