BINDER VD 23 - Manual (Page 75)

VDL (E2.1) 04/2014 page 75/107
14.1 Evacuation
• Close the aeration valve (5) and the fine dosing valve for inert gas (6).
• Turn on the vacuum pump.
• Turn the lever of the vacuum shut off valve (8) to
the “ON” position (valve open).
• Monitor the internal pressure on the pressure
display (3). The analog manometer displays the
running evaporation respectively the end of the
drying procedure. The scale of the manometer (3)
refers to an ideal ambient pressure of 1013 mbar /
29.9 inHg. Tolerance: 50 mbar / 37.5 mm Hg
(Torr) / 1.5 inHg (2.5% of the final scale value +
reading precision).
• When the desired end vacuum is obtained, turn
the VDL vacuum shutoff valve (8) to the “OFF”
position (valve closed). The reached vacuum is
now maintained.
Figure 18: Manometer display
The permissible end vacuum is 10 -2 mbar / 0.0003 inHg.
14.2 Breaking the vacuum (flooding with ambient air)
When the drying procedure is complete, the vacuum in the inner container is broken (flooded).
•
Open aeration valve (5) and fine dosing valve for inert gas (6)
• As soon as aeration valve (5) is open, fresh air is sucked in through the fresh air connection (12).
When the fine dosing valve for inert gas (6) is open, fresh air is sucked in through the inert gas con-
nection (11).
Fresh air is introduced into the lower part of the rear panel of the inner chamber where it is evenly distrib-
uted in the inner chamber. This supply of fresh air by under-flooding prevents turbulence of pulverized
drying material.
14.3 Operation with inert gas
When operating the VDL vacuum drying oven with inert gas, correctly follow the technical ventilation
measures, as described in the guideline BGI/GUV-I 850-0 on safe working in laboratories (formerly
BGR/GUV-R 120 or ZH 1/119 laboratory guidelines issued by the employers’ liability insurance associa-
tion) (for Germany).
During operation with inert gas, the unit is supplied with an oxygen displacing gas (e.g. N
2
). Inert gases in
high concentrations are hazardous to health. They are colorless and almost odorless and therefore practi-
cally 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.