Technical data

A freeze dryer should be aerated and the dry product should be

removed at the end of the drying process. Then the system should

be defrosted with warm water (+50°C max.) while the drain valve

is open. Then the drying chamber has to be wiped dry.

not simply let the freeze dryer stand at room temperature for a

long period of time since this is the time during which the tungsten

wire reacts with the surrounding atmosphere!

In addition, it is recommended to evacuate the unit for approx. 30

minutes with an

open gas ballast valve after defrosting and drying

in order to remove any residues which might react with the

tungsten wire.

7.3.2. Replacement and calibration

The vacuum sensor has to be replaced if “---“ is shown in the

vacuum field after the aeration of the system instead of “Atm” and

if the process and equipment information window shows error

message 41. If after the warm-up phase and the aeration of the

unit the vacuum display still does not show “Atm” but a value like

“800“, “600“ or “400“ mbar, for example, the vacuum sensor has to

be recalibrated. The warm-up phase of the vacuum measuring

sensor takes at least 5 minutes.

Calibration of the vacuum sensor:

The vacuum sensor has two calibration buttons labeled “adj“ and

“set“. The buttons are protected by protective caps. Remove the

protective caps of the buttons prior to calibrating the sensor. Use a

small pen (max. ∅ 2.5mm) to actuate the buttons. Refit the

protective caps after the calibration.

The digital recalibration to atmospheric pressure (Atm) and zero is

possible directly at the vacuum sensor using the button labeled

“adj” (adjust). The measuring transducer automatically recognizes

the calibration point. If a zero calibration has to be performed, the

actual pressure should be lower than 5.0x10

-5

mbar (factory

setting). Alternatively, the sensor can also be calibrated to a

reference value (see below). We recommend a warm-up phase of

at least 5 minutes before the calibration.

Buttons with

protective caps for

calibrating the

vacuum sensor

82 • Maintenance Operating Manual Freeze Dryer ALPHA 1-4 LSC / ALPHA 2-4 LSC