The physical characteristics of the foam used for base injection into tanks of burning petrol must be closely controlled to obtain extinction of the fire.
It is shown in this note that while suitable foam cannot be produced by the use of self-aspirating foam generators alone, it may be made by combining such a generator with a centrifugal pump. In this way, succeessful use is made of normal Fire Brigade equipment, without recourse to special foam pumps or large compressed-air foam generators.