- Author
-
Lundqvist, A.
- Title
- Brandsektionering genom vattenbegjutning--en experimentell studie.
- Coporate
- Swedish National Testing Institute, Boras, Sweden
- Report
-
SP REPORT 1991:28
1991
49 p.
- Keywords
-
compartments
|
cooling
|
walls
|
water
|
structures
|
pipes
|
spray nozzles
- Abstract
- [ABSTRACT IN ENGLIGH] This project is a continuation of an earlier carried out literature investigation. The literature investigation showed that water cooling of fire exposed structures could be a possible method of fire compartmentation, above all in industrial buildings. In this project, experiments have been made to investigate what factors influence the cooling effect of the water. The experiments were carried out in our vertical fire test furnace. The test specimen consisted of a 4 mm thick steel plate with outer dimensions of 2.4 m x 2.4 m. A system of water pipings was set up so that the water could be applied to the wall in two different ways, either with a perforated pipe at the top of the wall or with four spray nozzles which gave a shower spray all over the wall. The surface structure of the wall were varied to examine the significance of the surface roughness to the water demand. At each test the steel plate was heated to a certain temperature before the water was applied. The temperature of the wall, the furnace, the applied and drained water as well as the flow rate of the applied and drained water were measured continuously. The experiments gave a direct conception of the water flow rate needed to cool a hot thin steel wall. The tests also showed that it is very important that the wall is covered all over with a waterfilm. If the water flow rate is too small, dry parts will appear on the wall where the temperature will be very high. The "critical rate", i.e., the smallest water flow rate that gives a water film all over the wall, could be estimated by the experiments. This "critical rate" is different for each combination of surface roughness and water application alternative. It depends also on the initial temperature of the wall. If the surface structure of the wall is rough, instead of plain, a smaller water flow rate is needed to cool the hot wall. The water then drains more slowly and the water absorbs more heat from the wall. By analysing the heat balance at the different experiments, the cooling effect of the water can be estimated. A comparison between the calculated cooling effects at the different experiments shows the difference in utilizing the cooling capability of the water.