FIRE HAZARD OF THE CHLORATES

FIRE HAZARD OF THE CHLORATES

Necessity of Regulation in Storage and Handling of These Dangerous Chemicals— Cleanliness Absolutely Essential—Dangers of Mixing with Wood Dust or Other Substances—Ignition by Friction

THE most common, and therefore the best known, of those chemical compounds which are classed as ttie “chlorates” are the chlorates of potassium and sodium, each being of commercial importance in the production of coal-tar dyes, fireworks compounds, matches, in medical preparations, and sometimes in the production of oxygen; but, as is doubtless well known, these compounds have been produced in the past 3 or 4 years in evercreasing quantities as the principal base of high explosives necessary for the prosecution of the worldwide war, now happily closed, with the result that these basic compounds have been accumulated at various points throughout the country, in many instances without discrimination as to locality or consideration as to the possibility of disaster to life and property which is almost certain to obtain where such compounds are stored or handled.

Florence M. Griswold

Government Definition of “Explosive Ingredients”

The United States Government officially defines an “explosive ingredient” as follows:

“Any chemcial compound or mechanical mixture that contains any oxidizing or combustible units, or their ingredients, in such proportions, quantities, or packing that the ignition by fire, friction, or by concussion, by percussion, or by detonation of, or any part of the compound or mixture may cause such a sudden generation of highly heated gases that the resultant gaseous pressures are capable of producing destructive effects on contiguous objects, or the destroying of life or limb.”

This definition forms a part of an act of Congress passed in October, 1917, under the caption of “The Explosives Regulation Law,” which covers all matters relating to “regulating the manufacturing, distribution, use, or possession of explosives and their ingredients,” and its conditions specifically nominate as “explosive ingredients” the chlorates of barium, potassium, sodium, and strontium, to which might well be added the lead chlorate.

While this act was formulated as a means of certain control of the heretofore somewhat loosely enforced state and municipal regulations covering the matter of explosives, its prime value laid in the fact that its enforcement would serve to minimize the attempts against life and property by alien enemies, whose nefarious activities were all too prominent during the early days of the war. It is to be regretted that its enforcement as an emergency measure is now likely to become somewhat of a dead letter, notwithstanding the fact that past experience has frequently demonstrated the well-known and dangerous instability of these compounds and their liability to bring about disaster under seemingly slight provocation, and that fires and explosions due to their presence and handling serve to strongly emphasize the necessity for continued and increased caution by those responsible for the storage and distribution of these unstable compounds.

Knowledge of the dangerous nature of the chlorates is not a matter of recent acquirement or development, as they have for many years past given public evidence of their capacity for destructive activity, and have long been classed as “the most explosive substances met with which chemists and druggists have to deal,” and each new experience caused by the presence of these compounds simply serves to corroborate the truth of such conclusions; but, on the supposition that “familiarity breeds contempt,” past experience does not appear to have taught caution to those who handle these highly sensitive compounds; realization of this condition serves as justification for now repeating longand well-known facts which appear to possess the faculty of escaping our memory between recurring evidences of the tendency of the chlorates as trouble makers.

Explosive Constituent Chloric Acid

The explosive constituent of all chlorates is chloric acid, which acid, when in concentrated form, incites to the spontaneous ignition of organic substances such as paper, wood, straw, textile fibres, and the like, simply through its contact with them. All chlorates are powerful oxidizing agents, holding a large quantity or percentage of loosely combined oxygen, and while it is generally assumed that pure chlorates are not inherently of an explosive nature, they are known to become so when in intimate contact with organic matter and other substances not compatible with them— such, for instance, as sugar, meal, shellac, charcoal, sulphur, acids, and many other chemicals—and. in addition, explosion is almost certain to occur when they are subjected to the influence of friction, shock (as in crushing the hard lumps), concussion, and percussion; and when heated to about 752 degrees Fahrenheit, oxygen is liberated so freely as to sometimes set up a violent explosion.

Excerpts from a paper read before the National Firemen’s Association’s annual convention at Chicago.

Chlorates, as usually received from the factory, are packed in small, hardwood kegs, iron-hooped and paperlined, and of a capacity of about 100 pounds weight each. The weight of the material and the seeming rigidity of the packages appears to induce carelessness in handling, with the result that the shock and jar due to rough usage developes defects in the package, through which more or less of the material escapes and is scattered over the floor, thus becoming intimately mixed with wood dust or other organic matter, in which condition a proper mixture is provided for ready ignition or explosion as the result of friction caused by the workman’s shoes, or by the impact of the iron-rimmed keg on the mixture of dust and chlorate setting up that intensity of shock which results in ignition.

Some Instances of Sensitiveness to Ignition

As an illustration of the instability of these compounds and their sensitiveness to ignition under the conditions referred to, it may prove interesting, and at the same time ought to serve to instruct, to recite some of the facts developed in fires of record in which chlorates have demonstrated the characteristics indicated:

In support of the statement that rough usage of packages containing chlorate of potassium will cause ignition of the material, the record of a fire and explosion which occurred in the Silver Spring Bleachery and Dye Works, Providence, R. I., on February 1, 1895, shows that a fire which preceded an explosion was caused by friction set up by rolling or sliding the iron-bound kegs of chlorate over some loose crystals lying on a wooden floor and in contact with particles of dust. This fire was followed by the explosion of the kegs of chlorate, one after the other.

In 1908 a fire occurred in the warehouse of Thompson, Son & Williams, at Hulme, Manchester, England, and reported in the Chemist and Druggist, of London, wherein it is stated; “It appears that the warehouse contained many tons of chlorate of sodium, chlorate of potassium, and chlorate of barium, stored in barrels lined with paper.”

An investigation of the disaster was made by Major Cooper-Key, chief inspector of explosives, who reached the conclusion that the fire and following explosion were caused by both shock and friction by “a laborer who jumped from a barrel and struck a spark with his boot, and then saw the flame. Rubbing the place with his foot only made the flame worse, and soon afterward three explosions occurred,” the proved presence of a mixture of organic dust and chlorate upon the floor of the warehouse being the unquestionable cause of the rapid spread of fire when rubbed by the boot of the laborer.

The terrific explosion following a fire in the warehouse of Jarvis Company, March 26, 1918, in Jersey City, N. J., was ascribed to the fact that a workman carelessly threw a lighted cigarette on the accumulation of chlorate scattered over the floor, and it has been assumed that the glowing end of the cigarette ignited the chlorate; while this conclusion may serve in lieu of a better one, it is in evidence that the workman attempted to put out the fire by rubbing it with his foot, thus providing the necessary mechanical friction to insure more rapid spread of flame, as in the instance just recited, the general conditions in these cases being similar.

The Chemist and Druggist, of London, records the occurrence of a disastrous explosion and fire which took place in Pain’s fireworks plant in England in 1889, the concern at the time being engaged in producing a pyrotechnic device known as “stars,” the chemical ingredients of which consisted of chlorate of barium and potassium, nitrate of strontium, shellac, coal, and charcoal. “It was found, however, that one of the ingredients (Chartier’s copper) of one of the stars was distinctly acid and was the cause of the explosion.”

When chlorates become ignited large volumes of oxygen are liberated and add to the rapidity and intensity of flame, and the heat thus generated is liable to raise the temperature of contiguous combustible substances to the point at which their volatile and combustible gases or vapors are freely given off, thus intensifying combustion, and their combination with oxygen would provoke explosion; a like result would ensue through contact with charred or carbonized organic matter, such as wood, textile fibre, and the like, falling into or upon the mass of heated chlorate. In support of this statement, reference is made to the very serious explosion which occurred as an “after effect of a fire” at the Kurtz chemical works, St. Helen’s, England, May, 1899, as a result of which it was held in an action for damages due to the explosion “that chlorate of potash is a dangerous explosive in the presence of fire; perhaps from the gases emitted by the molten material in admixture with gases liberated by the combustion of other material in the vicinity.”

A careful technical investigation of this fire and explosion brought forth the conclusion that the fire did not originate in the chlorate, “where over 150 tons were stored in a pure state … the explosion, which was exceedingly violent (it was heard 27 miles off), was due to the effect of heat upon the chlorate itself,” or was the result of contact with oil of vitriol, “which was stored in large quantities near at hand. … Potassium chlorate is endothermic, and if the temperature of a large quantity of it were suddenly raised the oxygen might be evolved explosively and the whole might then detonate.”

A disastrous fire and explosion, accompanied by loss of life, occurred at the drug house of Tarrant & Co., in New York City, some years ago, which was ascribed to friction in handling raw chlorate of potassium, or in forming under mechanical pressure chlorate tablets containing sugar; a like fire and explosion occurred in the establishment of the Sharpe & Dohme Company, at Baltimore, where chlorate tablets (known as Santonin Crystals), made from pure and clean material, were being compressed on a rotary machine which had been previously used for the production of hundreds of tons of like tablets without accident; in this case the operator of the machine—a man of ten years’ experience in the making of such tablets—met his death by the rupture of the machine as a result of the explosion of the chlorate.

The foregoing recital of the established facts in relation to the peculiarly hazardous nature of the chlorates has been prepared with the intention of bringing forcibly to your attention the necessity for some restrictive measures being taken to insure their proper storage, handling, and use, in avoidance of disaster in the communities under your supervision and charge; and while it may not be hoped to secure enforcement of the very drastic regulations laid down in the Government explosives law, already cited, as its prime motive was to prevent “disloyal persons from procuring explosives or their ingredients,” it appeals to me that concerted and vigorous action should be taken to secure safety in the matter by the enactment of suitable restrictions to that end; and in this regard I am in accord with the suggestions of Chief Inspector of Explosives Major Cooper-Key, of England, which are as follows:

  1. —The elimination so far as may be possible of combustible material in the packages containing chlorate.
  2. —The establishment of separate buildings, of fireproof construction. for the storage of chlorate.
  3. —Absolute cleanliness, i.e., the outside of the kegs, the floor and walls of the store, should be kept clear of all dust and dirt, and no one should enter the building in his ordinary boots. Either these should be taken off or “overshoes” should be provided, as in a gunpowder magazine.

To these regulations should be added the further precaution of prohibiting the storage of chlorates in such locations and under such conditions that they might not by anv possibility of accident or design be brought into contact with other substances known to be incompatible with them, some of which have already been referred to. In other words, the segregation of chlorates from contact with all other matter or material should be as absolute and complete as possible to obtain.

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