Fire Safety Science Digital Archive

Experiments were conducted to study the effect of sprinkler operation on the exhaust of fire gases from the wet bench for a fire occurring in a clean room wet bench. In this study, the pressure loss across the sprinkler spray in a horizontally-oriented duct connected to the wet bench was measured and analyzed to address the following operation variables: orientation of sprinkler water discharge relative to exhaust flow, duct size, sprinkler model and orifice diameter, water discharge pressure, gas temperature and exhaust flow rate. The pressure loss increases with water discharge pressure and exhaust rate. As the sprinkler orifice size increases, the spray-induced pressure loss increases for the same water discharge pressure, but decreases for the same water discharge rate. Furthermore, discharging water against the exhaust flow induces considerably greater pressure loss than discharging water perpendicularly to the flow. The pressure loss data for sprinklers discharging perpendicularly into the exhaust flow can be correlated with the above operation variables. The correlation suggests that the spray-induced pressure loss is mainly due to the drag resistance of the water drops generated in the duct.