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VD (E3.1) 10/2020 page 50/179
6.4.2 Ventilation after completing the drying procedure (flooding with ambient air or
inert gas)
The duration of the drying procedure can be determined via the pressure display on the controller. When
the decreasing pressure reaches the set-point value, the drying process is completed. If the drying
monitoring (section 8.7) is activated, a corresponding message is displayed.
To break the vacuum (ventilation) after completing the drying procedure, set the desired pressure set-
point to atmospherical pressure (chap. 7). The ventilation valve opens, and ambient air or inert gas flow
into the inner chamber.
Regularly the inert gas connection / ambient air inlet “GAS/AIR” (4) is used for ventilation
Chambers can be equipped as an option with an additional inert gas connection / ambient air inlet
“GAS/AIR2” (5), which can be used alternatively. To do this, the controller function “GAS/AIR 2” serves to
close the valve of the standard connection “GAS/AIR” (4). Then the valve of the optional connection
“GAS/AIR 2” (5) is used for ventilation (chap. 8.3). This allows convenient switching when both
connections are used differently (e.g., for inert gas and ambient air).
Ambient air is sucked in through the inert gas connection / ambient air inlet (4) or (5). The ambient air is
introduced into the lower part of the rear panel of the inner chamber and is evenly distributed in the inner
chamber. This supply of ambient air by under-flooding prevents turbulence of pulverized drying material.
6.4.3 Ventilation / breaking the vacuum in case of a power failure
To be able to open the chamber in case of a power failure, remove the “Manual ventilation” plug (7) for
emergency ventilation, which is located on the chamber rear.
As long as there is a vacuum, never try to open the oven by force.
Make sure that the drying procedure is complete before breaking the vacuum. Otherwise, you
should wait for the power to return to continue the drying procedure
6.4.4 Operation with inert gas
When operating the VD vacuum drying oven with inert gas, correctly follow the technical ventilation
measures, as described in the DGUV guidelines 213-850 on safe working in laboratories, issued by the
employers’ liability insurance association (for Germany).
Inert gases in high concentrations are hazardous to health. They are colorless and almost odorless and
therefore practically imperceptible. Inhalation of inert gases can cause drowsiness up to respiratory
arrest. When the O
2
content of the air decreases below 18%, there is risk of death from lack of oxygen.
Any gas that might escape has to be led out via good room ventilation or a suitable exhaust system.
DANGER
Danger of suffocation by high concentration of inert gas.
Death by suffocation.
∅ Do NOT set up chambers in non-ventilated recesses.
Ensure technical ventilation measures.
Respect the relevant regulations for handling these gases.
When decommissioning the vacuum drying oven, turn off the inert gas supply.
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