A series of tests have been carried out on the extinction of a
petrol fire 30 cm diameter with a number of water sprays. The drop
sizes of the sprays varied between 0.2 to 0.6 mm, the rates of flow
between 0.6 and 4.0 g cm^-2min^-1 and the entrained air velocities between
200 and 500 crn/s. The preburn time of the fire was varied between
1 and 300 seconds. It was found that the extinction time was markedly
reduced by an increase in the rate of flow and the entrained air velocity
and by a decrease in the drop size. However, it was also found that
the most efficient sprays tested often did not give extinction when the
preburning time was less than 10 seconds, and for this reason the use of
water sprays is not advised as a reliable method for extinguishing this
type of fire. The mechanism of extinction of the fire is discussed.
