Characterisation of the water distribution on the surface of liquefied petroleum gas (LPG) tanks with a protective water deluge in operation has involved the development of techniques to measure the water film depth and the rate of water flow across the tank surface. The devised instruments and the experimental measurements are reported. The water distribution was found to be uneven, with many regions of the tank surface receiving less than the recommended amount of water. The water supply pressure, the sprinkler yoke arm orientation and the stand-off distance between the sprinkler nozzles and the tank surface were all found to influence the resulting water distribution. (C) 2003 Elsevier Ltd. All rights reserved.