Binder vdl 23 - Page 24

VDL (E3) 09/2019 Page 24/234
If the following precautions are not followed, the vapors resulting from heating of the solvent can ignite on
the hot walls of the inner chamber
Required measures for operation with solvent-containing materials that can form an
explosive mixture with air:
• Sweep the area for electrical equipment with compressed air or inert gas for at least 15
minutes. Sweeping must take place during the entire operating cycle and must be monito-
red at the manometer on the chamber front.
• Only after completing this sweeping time, put the chamber in operation.
• Take the auto-ignition temperature from the safety specifications of the solvent. In the case
of solvent mixtures, use the auto-ignition temperature of the material with the lowest auto-
ignition temperature. Make sure that the auto-ignition temperature is above 200 °C.
• Enter the temperature set-point (drying temperature) on the controller.
• Set the safety controller (temperature limiter class 2). Recommended setting: safety con-
troller mode „Limit“, safety controller value approx. 5 °C avove the set-point.
• During the drying process, use only those solvents for which the auto-ignition temperature
has been entered.
• Make sure that the technical ventilation is active. Introduce the drying material.
• Start the drying process. The heating unit is only released when a pressure threshold of
100 mbar is reached.
• The duration of the drying process can be determined by means of the pressure display
on
the controller. When the pressure drops to the set-point, the drying process is finished.
• Make sure that the technical ventilation is active. After termi
nation of the drying process,
ventilate the vacuum drying oven with ambient air or inert gas. Unload the loading material
and turn off the oven.
• Sweep the area for electrical equipment at least 15 minutes with compressed air or inert
gas.
• Make sure that the technical ventilation is active when emptying the condensate catchpot
of the vacuum pump.
• Before starting a new drying process with a different solvent, check again the auto-ignition
temperature at the safety specifications of the solvent. In the case of solvent mixtures, use
the auto-ignition temperature of the material with the lowest auto-
ignition temperature.
Make sure that the auto-ignition temperature is above 200 °C.