FLAMMABILITY OF PROPELLANTS 495 Table 2 l•esults of Burst/Fire tests, showing number of positive results out of number of tests. Nominal Solvent container Amount of butane size 10 g 20 g 40 g 80 g 160 g 6 oz 4/10 10/10 8/10 0/1 -- 80Z 0/1 10/10 9/10 9/10 -- Odourless kerosene 12 oz 1/1 10/10 10/10 10/10 8/10 16 oz 2/2 0/1 1/1 9/10 7/10 6 oz 2/lO 1/lO 1/lO o/lo -- 50% w/w Water 8 oz o/1 o/10 2/lO 1/lO -- w/w Methylareal 12 oz o/1 o/1 1/10 1/10 ø/lO Spirits 16 oz 1/2 0/1 0/1 1/10 0/10 6 oz o/lo o/10 o/lo O/lo -- s oz o/1 o/10 O/lo o/lo -- Water 12 oz 0/1 0/1 0/10 0/10 1/10 16 oz 0/1 0/1 0/1 0/10 ø/10 I • " I I I o Jo •'• •o - ,•,o •o i o 7o go go i•o Figure 1 Graphs comparing results of Burst/Fire tests obtained from butane and Arcton-propelled pressure packs, containing various levels of flammable material.

496 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS These results suggest very strongly that the butane/water system will tolerate a greater proportion of total flammable material than will the Arcton system, if equal fire hazards are accepted when a dispenser bursts. This is presumably a manifestation of the high efficiency of a water spray as a fire suppressing, and extinguishing, medium. FLAME PROJECTION TEST Flame projection tests based on the C.S.M.A. Method • have been carried out on the spray from dispensers containing mixtures of 100/120øC petroleum ether with 50/50 Arcton 11/12 mixture, and on mixtures of commercial butane and water with emulsifiers. The filling weights and valve specifica- tion were such as might be found on production packs of this type. As there is some change in the composition of the water/butane mixture during the discharge from the dispenser, tests were performed on full packs, and those from which 50%and 90% of the contents had been discharged. Figure oe Graphs comparing flame extension of butane and Arcton-propelled pressure packs containing various levels of flammable material, and at different degrees of emptiness in the case of butane. The results of these tests are plotted in Figure 7. Dispensers containing 50/50 Arcton 11/12 mixture at less than 40% w/w gave erratic results, due to poor spray characteristics and these have been omitted. The results again demonstrate the remarkable efficiency of dispersed water as a flame- suppressing medium.