【正文】 esults were observed, as significant increases in the critical rates of application were obtained for the longer preburn times. However, the values obtained for the critical rates were greater than the corresponding values obtained from the laboratory fires, indicating the importance of some scale effect. Furthermore, the apparent large differences shown between types A and B in the laboratory tests largely disappear in the larger fire tests. It is thought that this effect of scale is due in part to the way in which the wall of the tank affects the flow of foam in forming a foam blanket. With the small diameter laboratory fire tray, the foam quickly spread to the walls of the vessel forming a foam blanket upon which a significant depth of foam could be built. For the larger scale fires, a foam blanket appeared to be formed far less readily, and even when foam covered the surface of the fuel, it was more difficult to build up an impervious foam layer. The indications of a scale effect for this method of application are important since the practical problem of storage tank protection is concerned with fires many orders greater than those so far discussed. A small number of tests, therefore, were carried out on a much larger fire, 400 ft2, in a concrete dike to examine further the effects of scale. TESTS ON 400 FT2 Free Because of smoke pollution problems in the area where the tests weremade, it was not possible to carry out tests with long preburn times on the larger fires. The tests, therefore, were limited to applying foam from a standard foammaking nozzle to a 400ft2fire of 400 gal of regular grade gasoline (approximately 2 in. deep). A 2min preburn time was used in these tests. The nozzle provided a constant discharge of 40 gpm, an application density of gpm/ft2, which was directed as far as possible to the center of the test fire. The results obtained are shown in Table 3. TASLE 3. Results of the 18ft2Fire Test Foam type and properties Fire performance Hydrolyzed protein A expansion, 7。 25 per cent drainage time,2 min 30 sec. Hydrolyzed protein B expanmon, 。 25 per cent drainagetime, 3 rain 20 sec. No fire control. After 46 rnin of foam application, some reduction in flame intensity. No further reduction. Foam application stopped after 12 min. Fire reached full intensity again within an additional 2 min. Fluoroprotein . 70 expansion, 7。 25 per cent drainage time, 2 rain 25 sec. Fire controlled in 45 sec. Foam application stopped after min 15 sec. Fire out after 1 rain 30 sec. From the results of the laboratory tests and the 18ft2 fire, one might have expected that the 400ft 2 test fire would have been controlled readilyunder test conditions by the two hydrolyzed protein foam pounds applied at an application density of gpm/ft 2. One difference in the400ft2 test fire was that only a 2in. fuel depth was used as pared with deeper fuel layers on the smaller fires. It could, however, be an extension of the scale effect that was thought to explain the differences obtained between the small laboratory test fires and the 18ft 2 test fire results. LIGHT WATER Investigations of new foaming agents at the . Naval Research Laboratory led to the development of Light Water foam pound. There are a number of reports 57 relating its performance on shallow fuel layers associated with its use on aircraft crash fires. There are no test results reported on its performance on deep fuel layers。C to 80 176。 Joint Fire Research Organization. [3] Fry, J. F. and French, R. J., A Mechanical Foam Generator for Use in Laboratories, Journal of Applied Chemistry, Vol. 1 (1951), pp. 425429. [4] Burgoyne, J. H. and Katan, L. L., Fires in Open Tanks of Petroleum Products: Some Fundamental Aspects, ,Journal of the Institute of Petroleum~ Vol. 33 (1947), p. 158. [5] Tuve, R. L., et al, A New Vapor Securing Agent for Flammable Liquid Fire Extinguishment, NRL Report 6057, 13 March 1964, . Naval Research Laboratory. [6] Tuve, R. L., et al, Fullscale Fire Modelling Test Studies of 39。 and Protein Type Foams, NRL Report 6573, 15 Aug. 1967, . Naval Research Labora tory. [7] Fittes, D. W. and Nash, P., Light Water, Fiie, Vol. 61, No. 759 (Sept. 1968)pp. 170171,195.