THE GRAIN ELEVATOR CONSIDERED AS A SOURCE OF FIRES AND EXPLOSIONS

THE GRAIN ELEVATOR CONSIDERED AS A SOURCE OF FIRES AND EXPLOSIONS

以下有趣的摘录是Dedrick教授的前面论文，该论文最初发表在《手术米勒》中：

Elevators, particularly the heads, have been in the past prolific sources of fire. The old style elevator head, with the straight-across bottom, just a half-inch or so under the lower side of pulley, was especially dangerous, because it was a gathering place for dust. Many mills and elevators have been destroyed in that way, and undoubtedly many of the mysterious fires and explosions had their origin in the elevator heads. It is probable that in eight out of every ten fires that have their origin in elevators the source or point of origin is the head. There are various causes. There may be a single cause or factor or a combination of causes which starts the blaze. Elevators handling grain are particularly susceptible and dangerous as sources of fire: the grain dust which gathers in the heads at any point where it can lodge becomes very light, powdery and dry, and, being rather loose or free in character, readily ignites, and, if in any bulk, will burn at the first like punk, or tinder. Often the fire starts some hours after the elevator ceases to run, apparently lying dormant or smoldering until sufficient heat is generated to start the blaze, or a fire is started at the boot by some coals or burning dust dropping down the leg. Cases have occurred where fires started simultaneously at the top and bottom, or, rather, in attic and basement of mills and elevators. If the elevator shaft is out of level or line, it may cause the pulley to rub against the sides of the head, and, of course, the belt also, and the shaft may bear and make a seat for itself on the bottom or side of a hole in the head. The holes in the head through which the shaft passes are frequently but little larger than the shaft, leaving a scant margin of opening around the shaft, and, should the bearings become sufficiently worn, the shaft will rest and turn against a dry surface, and while elevator shafts turn slowly, yet the constant weight, sometimes considerable, and the friction kept up unceasingly for days at a time ultimately generate sufficient heat to char or set fire to the woodwork, or, perchance. dust adjacent to the shaft. Again, if the elevators rest on a good solid basement floor, they will stand solid and not settle. It may then be the elevator shaft that comes down with the gradual settlement of the building or floor that carries or supports the bearings. If the elevator is not plumb, the belt is sure to rub along one of the sides. The upper part of a section of the elevator head may become displaced or cocked over to one side, thus allowing the pulley to bear or run against some portion of the head. Improper speeds or defective discharge are sources of danger because of the liability of clogging down the elevator, and also because of blowing of dust, which may be sufficient to cause an explosion on contact with an open light, or even sharks generated by static electricity. When an elevator becomes clogged and chokes down, it is only a question of time when a fire will be started, unless the trouble is relieved, or the machinery stopped before the danger point is reached.