Preliminary study on fire protection of window glass by water mist curtain

Glass may easily break during a fire that can significantly accelerate the enclosure fire development. Water mist, as an efficient fire suppression technique, has been used for fire protection of an object due to fire radiant heat attenuation. The main purpose of this work is to investigate the behavior of the window glass heated by a fire and protected by a water mist curtain (WMC). Float glass with a dimension of 600 x 600 x 6 mm(3) exposed to a 0.16 MW gas fire was tested. The WMC was generated by a single orifice nozzle with K-factor of 1.01 L/min/ MPa1/2. The initial time of glass breakage, the temperature difference of the glass pane and the heat flux penetrating through the glass were measured and compared. The time of the window glass pane maintaining its integrated structure under the protection of WMC extends to more than 600 s comparing to 150 s of that without the protection of WMC. More than 38.5% thermal radiation of the fire would be attenuated by the WMC with thickness of 0.075 m and operating pressure of 1.0 MPa. The WMC demonstrates a better cooling capacity that can protect the glass from breakage more effectively comparing to water film with same flow rate. It is also found that the delaying of the activation of the WMC system contributes little to the crack or fallout of the float glass. The results may be helpful for providing guidelines on keeping glass integration in building fire scenarios.