TIPS ON BUYING A FREEZE DRYER
What Brand of Freeze Dryer is Best ?
The one that meets your specific needs and has
the performance needed for your
product. Before buying any Freeze Dryer, new or
used, inexpensive or costing hundreds of thousands of dollars,
you will need to know some of the drying characteristics of
your product. Basically, the highest optimum temperature at
which the product can be lyophilized should be known. Do not
confuse this temperature with the temperature selected for
secondary drying, which is much higher (25-35 C). The critical
product temperature for primary drying is much lower, generally
between -20 C and -30 C, and often lower. This is the product
temperature employed for optimum sublimation, and when exceeded
may induce "meltback" which results in the loss
of the batch.
The most common method for avoiding this problem
is to select a "safe" drying temperature, one that
is substantially below the optimum range. The drying safety
is assured, but at the cost of extended drying cycles that
are three to four times longer than the optimum drying time.
The result is added operating cost that may make the difference
between profit and loss.
One of the first questions often asked is "Can
my product be Freeze Dried?" Almost all persons who are
considering Freeze Drying for a process are interested for
a single reason:
They intend to sell the product in some marketplace.
If this is your ultimate intent, the question should be:
"Can my product be Freeze Dried for the
cost I need to meet desired profit levels?"
If cost of Freeze Drying is important, here
are some basic considerations:
Don't buy a Freeze Dryer just to establish the
viability of the process. Almost anything can be Freeze Dried,
given enough time. Books and water logged documents can be
restored to new by the lyophilization process, but it takes
months of continuous running to accomplish the result. This
is hardly a drying protocol that would be profitable for a
product destined for the general marketplace. If you are truly
unsure about your product's "Freeze Dry-Ability",
consider having it processed by contract drying on a per run
basis. Normally, the charges for this type of drying "run"
is between $600 and $1500 dollars, thousands less than the
cost of buying a small Freeze Dryer, which will probably be
too small in capacity for production use.
Beware of developing drying protocols that cannot
be duplicated on large scale production Freeze Dryers. This
is one of the most common mistakes seen in the pilot drying
phase. Small laboratory and pilot Freeze Dryers are generally
not designed like production Freeze Dryers, so the results
are often not scaleable when the time to produce the product
is needed. Some of the significant differences are:
The temperature capability of the lab Freeze
Dryer, both with respect to freezing speed and ultimate temperatures
(For example, many lab units will freeze below -55 C , below
the practical limit of production equipment) are completely
different from production Freeze Dryers. If freeze drying
protocols are developed without consideration for ultimate
production, the results can be disaster at the profit line.
This is especially true if you intend for your product to
be freeze dried by an outside source, such as a contract packager.
There are pilot Freeze Dryers which are designed
as small scale production units, and which will deliver accurately
scaleable production cycles. However, they are generally not
offered for sale, due to the high cost of fabrication. Most
are purchased by Pharmaceutical firms who produce products
with high profit margins.
Unless you can use the laboratory freeze dryer
for other work, or if the size of the lyophilizer is suitable
for your ultimate production, they are a poor investment,
and you should consider spending your budget in a way that
will further your end needs.
Continue
>>
