SAWDUST TO PUT OUT FIRES.

Dunstan Times, Issue 2676, 28 July 1913, Page 8

SAWDUST TO PUT OUT FIRES.

To utilise ordinary sawdust as a fire extinguisher would baldly occur to most ~oi us—hut that only shows how stupid wo arc. In a report made to tho Associated Factory .Mutual Fire Insurance Companies, Mr E. A. Punier, i Huston engineer, shows that it may he used oll'e-etively for this purpose n dealing with small outbreaks ol liquid combustibles, such as lacquer and gasoline, winch arc usually difficult to extinguish by ordinary means. Sand is gem rally considered the best thing to use in such cases when it can be applied promptly, but the tests showed sawdust to he greatly superior, says Industrial Engineering (New \ork), abstracting an account in The Mechanical Liiginecv: “The tests were made with fiat rectangular tanks in which a quantity of combustible was poured and ignited and allowed to burn for about a minute before efforts were made to extinguish the flames by spreading a few shovelfuls of sawdust on the .surface of the liquid. It made, little difference to the effectiveness of the sawdust as an extinguisher whether it was damp or drv. and whether it was the product of hard or soft woods. A number of commercial lacquers, as well as samples of gasoline, were tested in this way, and in aH cases the flames were extinguished in from 25 to 50 seconds, and with a very thin sprinkling of sawdust. When efforts were made to use sand a much larger quantity was required, and the process of extinction was much slower. “The efficiency of the sawdust seems to he due to its blanketing action in floating for a time on the surface of

the liquid and -excluding air, and j naturally its efficiency is greater_ on ■ viscous liquids than on thin ones, since ( it floats more readily °u the former | than on the latter. The amount of | moisture contained in the saw'dust was apparently not a factor, since sawdust ! which was dried was just as efficient. | Sand appears to be less satisfactory, : because it sinks through the liquid and has not the same blanketing action, i It was found, further, that the effici- j oncy of sawdust as an extinguisher was greatly increased by mixing it with sodium bicarbonate —ten pounds to a bushel of sawdust —since this material : when heated liberates carbonic acid. Sawdust itself, however, is not easily j ignited, and burns without flame, while j it would be difficult, if not impossible, to ignite sawdust mixed with bicarbonate with a carelessly thrown match. “Of course, it is not suggested that sawdust is a material to use when once a conflagration has got hold, but the tests clearly show that in many works where lacquer and similar inflammable substances are liable from some accidental circumstances to ignition, either in tanks or from leakage on to a floor, a, supply of sawdust, especially if it s biearbonated. is most convenient for stamping out the initial fires from which big ones spring.”