Experimental studies on thermal and smoke blockage by water curtains

A drencher system is commonly installed to substitute a fire resistive barrier. Operating the system is expected to stop the spreading of heat and smoke. It is important to assess whether the discharged water curtain (or screen) can block thermal radiation and prevent smoke spreading. The amount of air voids denoted by porosity in the water curtain is the key issue and will be studied experimentally in this paper. Three nozzles commonly used in the industry were selected and evaluated experimentally with two parts of study. The first part was on taking photographs of the moving water curtain discharged from the nozzles. The porosity describing the amount of air voids inside the discharged spray was then analyzed. The second part was full-scale experiments on assessing the fire resisting behaviour. A two-room structure was constructed with a fire room and a protected room. A water curtain was discharged to isolate the opening between the rooms. Thermal radiative heat fluxes in the protected room before and after discharging the water curtain were studied. Smoke spreading through the water curtain from the fire room was also observed. Results indicated that the water curtain discharged from the three selected nozzles would give high porosity. Therefore, only thermal radiation can be blocked. Smoke can still spread through the water curtain. However, the protected room can be kept relatively cool.