Fisher Bioblock Scientific 101041, Operating Manual

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Operating Manual Freeze Dryer ALPHA 1-4 LD-2 / 2-4 LD-2 , Version 0203, Page 34
4.3 Final Drying
The final pressure in the drying chamber depends on the ice condenser temperature
according to the vapour pressure curve above ice:
e. g.
1.030 mbar correspond to -20
°
C
0.370 mbar correspond to -30
°
C
0.120 mbar correspond to -40
°
C
0.040 mbar correspond to -50
°
C
0.011 mbar correspond to -60
°
C
The unit is in operating condition if the temperature of the ice condenser is lower than
-50
°
C and the pressure is lower than 0.120 mbar.
The final pressure measured by the vacuum sensor when there is no product in the
unit and its corresponding ice temperature value is mainly determined by the warmest
place of the ice on the ice condenser chamber. Moreover, this value is affected by
residues or parts of solvents in the product with a higher vapour pressure.
4.4 End of Drying and Venting
A rough indication of the end of drying is the vacuum and the ice condenser
temperature. The ice condenser is no longer loaded and reaches the final temperature
of approx. -50
°
C to -54
°
C. The pressure in the drying chamber decreases according to
the ice condenser temperature.
The vacuum pump is switched off and the drying chamber is vented by a rubber valve
or the defrosting water valve. A vacuum release valve for venting with nitrogen,
another inert gas or air is available as accessory.
Then the unit is switched off and the product is removed.
4.5 Defrosting
Defrosting of the ice condenser is carried out at room temperature or with warm water.
At a maximum the ice condenser chamber may be half filled with water.
During filling it is important that no water gets into the pipe connection for the vacuum
pump and vacuum measuring sensor!
The defrosting water is drained through the defrosting water valve at the left side of the
unit. To do this, a hose is put onto the nozzle. The defrosting water is collected in a
vessel.