Designing Your Freeze Drying System
Answer these key questions to successfully design your Modulyo
freeze drying system.
Will this freeze dryer be used for a single application or
multiple applications?
Consider not only the primary application, but also other, less
frequently performed applications, for your freeze drying system.
For example, flask drying may be successfully performed using a
column manifold, but if loose material will also be dried, a drum
manifold, with its large internal cavity that accommodates shallow
trays, might be a better choice.
What type of sample containers will you use with your freeze
drying system?
Will your sample be dried in flasks, vials or ampules, or will
it be loose material that requires shallow trays? The type and
number of sample containers will dictate not only the type of
drying accessory, but also the size of the ice condenser module.
Loose material in large shallow trays requires both a larger ice
condenser and a larger drying accessory than samples dried in 2 ml
glass ampules or 10 ml vials.
What is the total volume of ice to be extracted at one
time?
Ice condensers are rated by the maximum volume of ice they can
hold before they need to be shut down and emptied. Routinely drying
300 ml of frozen sample in two 1 liter flasks would easily be
accommodated by the 1.5 liter MicroModulyo. Drying sample material
in twenty, 1 liter flasks that are each half full would require the
ice capacity of the SuperModulyo.
What is the minimum pump displacement capacity required to
operate the freeze drying system?
In order to keep the sample frozen during the entire freeze
drying process it must be kept under constant vacuum. Column
manifolds used on a MicroModulyo have a small internal volume and
therefore do not require a large capacity pump. Some freeze drying
systems however, such as those that are used to dry bulk material
in trays, have larger internal volumes and require a larger
capacity pump to evacuate the total internal volume before the
sample begins to thaw.
What is the maximum temperature at which all of the solvent can
be successfully trapped before it reaches the vacuum pump?
Modulyo ice condensers operate at a nominal temperature of -50
°C. This is more than cold enough for the vast majority of freeze
drying applications. Some applications, however, will require lower
temperatures to protect the pump. For these applications, Thermo
Electron offers a temperature trap to supplement the Modulyo ice
condensers.
