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A CLOSED SYSTEM
6.1 WHAT IS A CLOSED SYSTEM?
As previously described, in order to
freeze dry food, your machine will
use a vacuum pump that removes
the air and creates a vacuum
environment. In order to achieve
adequate vacuum pressure, it is
VERY IMPORTANT to ensure that all
valves are closed tightly. If there is a
leak somewhere in the system, the
freeze drying process will not occur.
⚠
WARNING: You may think there
is not an air leak in your machine
because the door will not open (a
sign that you are pulling a vacuum).
However, it is possible to achieve a
less than suitable vacuum pressure
for freeze drying yet have enough
vacuum to be unable to open the
door. Initially, >2500 is displayed.
Within 10-20 minutes you should see
the number 2500 begin to decrease.
Drying occurs when the vacuum
pressure descends to 500 mTorr
(also displayed). If after 30 minutes
the 500 mTorr has not been reached,
then finding leaks is a logical next
step. Check to make sure the drain
valve is closed. Check to make sure
the door gasket is sealing properly
(clean the gasket in warm water and
reinstall—do not wipe dry because lint
may prevent a good seal).
While every precaution has been
made to ensure that there are no
leak points in your vacuum system, a
situation could arise where there is a
leak point. It is valuable to check the
following possible leak spots in order
to achieve optimal freeze drying.
6.2 POSSIBLE LEAK POINTS ON THE
VACUUM PUMP
• Vacuum pump hose connections
• Vacuum pump port knobs are
not tight
• Vacuum pump oil is contaminated
• Vacuum pump oil level is too low
• Gaskets in vacuum hose are cut
or damaged (this may occur if
the vacuum hose is fastened too
tight)
For images of the previous possible
leak spots and greater detail about
your vacuum pump, review the
instruction manual that came with
your vacuum pump.
6.3 POSSIBLE LEAK POINTS ON THE
FREEZE DRYER
• Drain valve is open
• Vacuum pump hose not
connected tightly
• Door not properly shut
• Door gasket not clean inside and out
• Door needs adjustment
