Viking Pneumatic/Pneumatic Double-Interlocked Preaction Systems utilize a Viking Deluge Valve controlled by pressure maintained in the pneumatic release system and supervisory pressure maintained in the automatic sprinkler system. BOTH the release system must activate AND supervisory pressure must be relieved from the sprinkler system before the deluge valve will open to fill the sprinkler system with water. If the pneumatic release system (alone) operates due to fire, damage, or malfunction, an alarm will activate, but the deluge valve will NOT open. If the sprinkler piping is damaged or a sprinkler is broken or fused, but the release system has not activated, an alarm will activate but the deluge valve will NOT open.