A blast valve is a specialized mechanical safety device installed within air ducts or ventilation openings to protect a facility from blast pressure. During normal conditions, the valve allows air to flow freely through the ventilation system. However, when an explosion occurs and a shockwave travels through the ductwork, the blast valve automatically closes to block the incoming pressure wave.
This rapid closing action prevents the blast wave from entering the protected area and damaging internal systems. Blast valves are typically designed to withstand high levels of overpressure and are capable of operating automatically without requiring any external power source.