DUST IS DYNAMITE

Southland Times, Issue 23610, 10 September 1938, Page 13

DUST IS DYNAMITE

By

Eric Hutton

TORONTO, Canada. DUST is dynamite. The wives, and families of 45 miners working in a coal pit at Grundy, Vancouver, learned thgt in a cruel manner only last month when dust in the mine ignited and literally “blew the top off the mountain” in which the shaft was located.

The earth-shaking blast snuffed out the lives of the 45 workers, some of whom were not even near the mine. Two men were decapitated by an eight-ton motor sent hurtling down the mountain by the terrific force of the explosion. A mine car was blown 50 feet into the air, killing one man and crushing others. A spark from a mine cable was believed to have ignited dust deep in the shaft. Flames spurted 200 feet from the entrance to the mine following the blast and the heat was so terrific that 400 men were restricted to 30-minute work periods during the rescue. They were hampered during early hours until arrival of oxygen tanks similar to those used by Nova Scotia’s famed Draegermen in rescue work.

Only a few weeks earlier, grain elevator employees at New Orleans learned at first hand the lethal qualities

of dust when a blast demolished a big elevator, killing several men and doing hundreds of pounds’ damage. In Toronto a few years ago coal dust exploded in a shed and two men were severely burned. What set the dust off was never determined. An English woman also found that out recently when she was “making up” at her dressing table. Accidently she knocked over a box of face powder—which is merely a form of dust to the chemist. Almost, instantly she was enveloped in a sheet of flame. The powder particles in the air had ignited from an open fire in the room. The woman leaped through a window. She was badly burned, but lived. A housewife found that a bag of flour in her storeroom had been nibbled by mice, so she threw it down the incinerator shaft of the apartment 'building. The explosion that resulted when the “white gunpowder” reached the fire in the basement was so terrific that the woman was instantly killed, along with three others. It is hard to realize just how explosive any kind of organic dust can be until it is demonstrated. Up at the fire marshal’s office, Lionel Bishop, who lectures on such things, puts on a simple demonstration which every housewife should see. Clothed in fireproof overalls, Mr Bishop stands over a tiny burner. Slowly he drops a handful of com starch on to the flame. With a “whooosh!” a pillar of flame leaps up, high as the ceiling. “That,” said Mr Bishop, “could happen in anybody’s kitchen.” “Dust,” they will tell you at the fire marshal’s office, “has actually a wider explosion range than gas. That is, the proportion of explosive particles to air can be more varied in the case of dust, and still explode. It is an uncertain . business. “The practice .of dropping loose household dust into a furnace is distinctly dangerous. If even it doesn’t blow up the house, it may blow up the thrower.” Wood dust used for cleaning pelts exploded in a Toronto plant a couple of years ago and killed one man. During harvest time in 1936 a thresher on a farm owned by a Toronto man suddenly exploded into a million fragments. Investigation showed that grain dust had supplied the “motive power” of the detonation. These are “homey happenings,” however. What the “dust engineers” constantly seek to reduce are the holocausts in industrial plants. In the last 10-year period for which figures are available, in the United States alone, 150 persons were killed and 363 injured in dust explosions which cost industry £3,000,000 in property damage. The most unlikely substances produce a dust which will turn to dynamite when least expected. Few industries processing natural products are free from the menace of dust. Soap, soy beans, sugar, cocoa, powdered milk, spices, all have death-dealing explosives for by-products. Wheat dust is by no means the most explosive of the organic dusts, but because more wheat is handled, milled and stored than any other grain, some of the most disastrous explosions have been in wheat elevators and mills. Canada’s worst dust disaster occurred in Peterboro in 1916, when 17 were

killed in a feed and cereal mill and £400,000 damage done. Three years later a grain elevator went up at Port Colborne, killing 10 and causing £300,000 damage. Another explosion caused by dust killed two workers some years ago in Quebec province. In the United States and Canada, no fewer than 28,000 plants, employing nearly 1,500,000 persons, are subject to the hazards of dust explosions. Industry has already paid a toll to dust of well over 500 lives and £10,000,000 in money. Only in recent years did scientists discover that dust is explosive. Before that a lot of explosions remained mysteries. But since then much work has been done by Dr David J. Price, chief engineer of the bureau of chemistry and soils, United States Department of Agriculture. “Just now,” he said, “we are working out the limit of dust concentration which is explosive. The explanation of why dust explodes is that each particle is inflammable, and when one. ignites, the fire spreads rapidly to others, building up tremendous pressure if there is no escape.” What happens to a building when a dust explosion occurs in it is the subject of another demonstration _by Mr Bishop. He placed a small spirit lamp inside a stout metal box, an opening in which was covered by heavy paper clamped in place. When a charge of com starch was blown in by a bellows, the paper burst with a bang, and flame shot out. But when a hole was left in the paper, the powder merely burned without exploding. “Solidly built rooms are more dangerous and suffer worse damage in an explosion,” an official of the fire marshal’s office said. Modern grain elevators have hinged windows which swing outward. If there is an explosion, the window simply swings out, and the building is saved. “Another safety measure is to score the glass in windows, providing a weak spot that will break easily under pressure and provide an outlet.” Inspectors of the department who investigate fires usually reach the scene after the fire is out, but recently an official was right at the scene of a dust explosion—too close for comfort, in fact. He happened to be in Timmins when a store caught fire, and hurried to the scene. Just as he got there a big window was blown out by a blast, just missing him and injuring two others. That was a smoke explosion, which comes under the heading of dust Smoke is unburned carbon dust, and under favourable circumstances, will explode as readily as other dusts. One of the characteristics of a dust explosion is that it tends to propagate itself. It may start in a small way in one room of a factory, but the blast stirs up dust in the adjoining room which also explodes, and so on, leaving a trail of destruction. Modern practice is to have window ledges and other places where dust may collect slope down instead of being flat, and to sweep dust by vacuum suction instead of by brooms. Air-conditioning, which removes dust from the air almost, as fast as it forms, and which is being used in industry increasingly, practically eliminates the danger of dust explosions.