Abstract: Air vent for protecting the public potable water system against terrorism and sabotage. Conventional air vents allow the movement of air in and out of an enclosed reservoir structure but do not stop the penetration of liquids or solids. The present invention allows the movement of air but will not allow any liquids or solids to pass through the vent, even if these liquids or solids are being applied under pressure. This is accomplished by an energy dissipating arrangement of S-shape structural members.

Abstract: The purpose of this Air Vent is to safeguard the security of the public potable water system, especially in such enclosed structures as reservoir and clearwell and other vital air vented installations against sabotages, vandalism and other accidental contamination by animals or birds.