An external anti-flood device is required when Viking Model E-1 Accelerators are installed on dry systems according to Viking Model E-1 Accelerator Trim Charts. The Model B-2 Anti-flood Device is for use on Verband der Sachversicherer (VdS) approved trim only. The dry system air supply must be connected as shown on the trim chart for the model dry valve used. In the SET condition, the Model B-2 Antiflood Device is designed to prevent system pneumatic pressure from entering the intermediate chamber of the dry valve. In fire conditions, when the Model E-1 Accelerator operates, the anti-flood device opens to allow system pneumatic pressure to pass directly into the intermediate chamber of the dry valve, causing it to open. After the dry valve has opened, flooding the system with water, the anti-flood device prevents water from entering the Model E-1 Accelerator where it could foul and plug the restricted orifices.