Chapter 4: Using Your Freeze Dryer
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23
Alarms
A number of unusual events may occur during a lyophilization procedure that
can adversely effect the operation of the freeze dryer. If an event occurs, the
alarm indicator flashes and the beeper sounds.
The beeper automatically mutes itself after one minute. The specific alarm
can be identified by pressing MENU. Pressing MENU multiple times
displays multiple alarms if they have occurred. The following “out of
specification” conditions initiate an alarm:
Power Failure
If a power failure occurs during a freeze dry process, the vacuum control
valve allows air to bleed into the freeze dryer system. If the failure is of a
short duration and the collector does not warm up excessively, when power is
restored the freeze dryer restarts and resume operation of the refrigeration
and vacuum systems. If the power failure lasts for a longer duration and the
collector warms above safe limits, when the power is restored, the freeze
dryer will not automatically restart. This prevents melted sample from being
drawn into the collector and prevents liquid from being sucked into the
vacuum pump.
When power is restored, the alarm indicator flashes and the alarm beeper
sounds. When the MENU button is pressed the display shows:
Press and hold SELECT for five seconds until the error message is cleared
from the display.
Line Voltage Out of Range
If the voltage supplied to the freeze dryer varies beyond allowable limits, the
alarm will be activated. When an alarm occurs, press MENU and the display
shows:
The alarm self-cancels when the proper voltage is restored. The high and low
alarm points are preset at the factory to correspond to the normal allowable
voltage variations based on the nominal voltage specified for the freeze dryer.
Some models may be operated outside the normal voltage limits. See
Appendix C
. If necessary, the high and low alarm points may be adjusted for
these models. See
Chapter 8.
POWER FAIL
HOLD SELECT TO CLEAR IT
LINE VOLTAGE ERROR
