VD (E2.1) 07/2017 page 55/96
14.3 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 (formerly
BGI/GUV-I 850-0, BGR/GUV-R 120 or ZH 1/119, 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.
WARNING
High concentration of inert gas.
Risk of 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, shut
off the inert gas supply: Close
valves (4) or (6).
Install a pressure reducer for inert gas operation. Set the pressure reducer to a pressure slightly above
ambient pressure. Ensure that the pressure reducer will open. Do not change this setting in order to avoid
perturbation inside the oven and release of big quantities of inert gas after flooding the VD.
Following evacuation, an inert gas, e.g., nitrogen, is led into the inner chamber via the air/gas valve (4)
(VD 23) or the fine dosing valve for inert gas (6) (VD 53, VD 115), until pressure compensation with the
atmosphere occurs. Depending on the individual application, you can perform a second evacuation and
repeat the inert gas flooding.
When the inert gas fine dosing valve is open, a maximum of approx. 0.6 m³/h gas flows into the inner
chamber. The introduction of inert gas by under-flooding in the lower region of the inner chamber rear
wall and the extraction at the inner chamber ceiling allow an effective inert gas flushing.
If the oven is charged to full capacity, depending on the load, deviations from the specified
heating up times may occur.
To Next Page
Loading...
