Safety cabinet – many people know it, but not everyone knows how to use it properly … Part III

What should be observed when working under a Class II safety cabinet? The safety cabinet should be switched on a few minutes before starting work to ensure optimal airflow. A common occurrence in laboratories is when the sash is raised higher than permitted before starting work, either to thoroughly clean the work surface or to bring several items, such as pipette tips or smaller devices, into the interior for subsequent work. The sash was then forgotten to be lowered accordingly. Or it was deliberately left slightly higher because it might be more comfortable to work with a larger opening. If the sash is not set in the intended position, the safety cabinet will emit an alarm, which should not be ignored, as the safety of the employees inside cannot be guaranteed under these conditions. Another common occurrence is the attachment of work instructions or information about the work being carried out, which are "conveniently" attached to the front of the work surface by sucking in air. Of course, loose sheets of paper will remain in place, but they will also prevent the uninterrupted airflow through the safety cabinet, which also means that full protection is not provided. The same applies if arms are placed over large areas of the ventilation slots. In this case, support supports can be installed to keep the ventilation slots sufficiently clear. It is also important to ensure that the capacity of the safety cabinet is not overloaded. This means that the workbench must not be used as a storage area for materials. Likewise, only as many employees should work at the workbench as permitted by the manufacturer. This also means that the workbench should only be equipped with the material required for the work. It should be noted that open windows, strong air currents outside the workbench, and strong heat generation inside the workbench, for example from a Bunsen burner, can impair the airflow. If hazardous substances leak out from under the workbench, the workbench should not be switched off until it has been appropriately disinfected. Further information can also be found in the BG Chemie leaflet B 011.