Freeze-dryer Epsilon 2-10D LSCplus
5 Set-up and connection
Version 07/2022, Rev. 3.0 of 20/07/2022
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Translation of the original operating manual
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5.2.2
Aeration
DANGER
Risk of injury caused by bursting of the chamber
The double chamber is designed for vacuum. It is not a pressure vessel!
In the event of a malfunction, an impermissible excess pressure may build
up in the chamber, which may cause the chamber to burst.
This may lead to life-threatening injuries.
• Do not use the freeze-dryer when it is pressurised (excess pressure)!
• We strongly recommend installing a pressure relief device (e.g. a
safety valve or rupture disc) with a sufficient rating.
During the freeze-drying process, the aeration medium is used for vacuum
control by way of controlled gas inflow (gas injection). When the drying
process has finished, it is used for aerating the chamber to atmospheric
pressure.
Usually, the ambient air is used for the aeration. However, the chamber can
also be aerated with an inertisation medium (e.g. nitrogen) via the hose
connector of the aeration valve.
The freeze-dryer is equipped with one aeration medium connector (see
chapter 2.1.1 - "Functional and operating elements"). Downstream of the
aeration medium connector, the pipe branches out into a gas injection
branch and an aeration branch.
The gas injection branch includes a precision needle valve for the
preadjustment (see chapter 5.2.2.1 - "Precision control needle valve for air
injection")and a solenoid valve which are installed in series. In combination
with the pressure control valve in the suction line of the vacuum pump, this
configuration enables very precise vacuum control during the freeze-drying
process thanks to the combined evacuation and injection of gas.
The aeration branch includes a manual control valve for preadjusting the
volume flow and, thereby, the aeration rate, and a solenoid valve which are
installed in series.
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5.2.2.1
Precision control needle valve for air injection
In addition to the aeration valve, a precision control needle valve is also
installed (position see chapter 2.1.1 - "Functional and operating elements").
The precision control needle valve is used to pre-adjust the volume flow. If
the actual value is below the preselected vacuum value, this valve will open
briefly, thereby ensuring a constant vacuum in the freeze-dryer.
NOTE
The precision control needle valve is pre-adjusted at the factory.
Using the precision control needle valve, the volume flow must be pre-
adjusted according to the chamber pressure at which the freeze-drying
process is to be performed. The lower the desired chamber pressure is,
the lower the volume flow has to be pre-adjusted in order to prevent the
vacuum from oscillating or from showing regular peaks.
