FIRE HAZARDS

Ellesmere Guardian, Volume LIX, Issue 86, 28 October 1938, Page 7

FIRE HAZARDS

DANGERS OF SODIUM

CHLORATE

The following article, written by Mr R. E. R; Grimmett, chief agricultural chemist of the Agricultural Department, and published in the September issue of the Agricultural Journal will be of interest to all. "Now that the preparations for the coming season's campaign of ragwort destruction are being made, it is well _Jp take stock of the fire dangers to those who handle sodium chlorate," wrote Mr Grimmett. "At the moment no material is in sight which gives any promise of replacing chlorates in a general way as a ragwort-killer. Chlorates are used either in combination as the sodium or calcium salts or in various mixtures with other materials, such as calcium chloride,

caustic soda, or carbonate of lime, which tend to reduce, but do not eliminate, the risk of fire. "Casual farm hands or children are, perhaps, those most likely to be exposed to risks, the latter especially from their experimental proclivities. Those having charge of the material should do everything to avoid children having access to it, as 'gunpowder,' made by mixing it with certain inflammable materials, may be an excessively violent and dangerous explosive, and serious accidents have occurred in this way. At times, however, even experienced workmen may suffer from certain of the less obvious dangers associated with the routine use of chlorate mixtures. "The 'lime chlorate' mixture has become a standard one in many parts of the country, and, in general, is much safer to handle than unmixed sodium chlorate, either in dry form or solution. Because of the fact that the chlorate is very soluble in water while the lime is not, however, any damping of bags containing it is likely to lead to the formation of a film of saturated chlorate solution r -'" 1 on the surface of the lime particles. This solution travels by capillary attraction to the surface of the bag when the latter subsequently dries out. Thus the sacking may become impregnated with sodium chlorate and when dry (for instance, after emptying in sunny weather) extremely inflammable."

Probably this was the reason for the somewhat unustial accident reported to the officials of the Agricultural Department from Paeroa. Ten men employed on ragwort work by the Ohinemuri County Council - were returning by lorry to Paeroa when the vehicle suddenly burst into flames. It was unloaded except for a number of bags which had contained lime-sodium mixture and which were being brought back for refilling. It was not known how the fire started. None of the men was smoking. The tailboard of the lorry was hanging down and swinging with the motion of the vehicle and it was assumed that a little sodium must have got into position so that the friction from the swinging tailboard fired it. The men had to jump from the moving lorry to save themselves from burning, as the vehicle was enveloped in flames so rapidly that there was no time to stop it to enable the men to alight. The County Council had handled between seven and eight hundred tons of the lime sodium since November, 1936, and this was the first accident. "The moral," added Mr Grimmett, "is that sacks containing lime-chlor-ate mixture should not be allowed to become damp, and if this happens they should be thoroughly washed in running water (as, for instance, in a stream) and dried out before being used again. Any marked stiffness in niry bags should be regarded with suspicion, as it may indicate that a

crust of sodium chlorate has formed

over the fibres. A further and obvious V precaution which should be observed is that no workman should be allowed to travel in the body of a lorry where sodium chlorate or lime chlorate mixtures, or bags which have contained .them, are being transported."