Ventilation Duct Fire Dampers and Shock Valves

Buildings located in industrial gas production areas are normally designed to withstand explosion pressures from a design accidental event in the plant. To protect personnel and equipment inside buildings, installation of shock valves is the normal procedure. Experience with shock valves is, however, that they require maintenance, are expensive, have corrosion problems, and add pressure losses in the ventilation system. Alternatives are to reinforce fire and gas dampers in areas where shock pressures are moderate. Design pressures and possible effects of damping chambers and location of dampers are important variables. The paper summarizes some of the main results and conclusions provided from a study done for the Norwegian company Hydro Oil & Energy. The main conclusions drawn are as follows: Fortification shock waves have normally significantly shorter durance compared to explosion pressures from a typical accident in a gas process plant, and fortification design guidelines should not be used directly. Dampers should be designed to withstand pressures 1.5–1.8 times the side-on shock pressures unless the dampers are mounted flush with the building wall or roof, due to the reflecting shock pressure from a closed damper mounted inside a ventilation duct.