Multiple-jet white-smoke generators

Abstract

Descriptions are given of equipment devised for the generation of fairly large quantities of an optically dense white smoke and special attention has been paid to the need for delivering this through long ducts or against an appreciable back-pressure. The smoke consists of very small particles of condensed paraffin vapour and is obtained by directing jets of cool air on to high-speed jets of the vapour issuing from very small orifices. The optimum outputs are about 6 cu ft (170 litres) and 8 cu ft (230 litres) per minute from No. 1 and No. 2 generators, respectively, but considerably larger quantities can be delivered with a slight loss of opacity. Under normal operating conditions the rate of use of paraffin is rather less than 2 cu in. (33 c.c.) (No. 1) and 3 cu in. (49 c.c.) (No. 2) per minute.