The Cork Factory—An Explosion Breeder
Many Materials Employed in Cork Factories Contribute to Dangers of Flash Fires and Explosions—Processes Involved
CORK is used in quite a variety of products, such as bottle stoppers, insulation, and floor coverings. In its raw form it is not dangerous, but when passing through fabrication into useful articles it is put into such condition as to frequently create severe explosion hazards.
The modern cork factory includes certain operations which are characteristic of all and these will be briefly outlined here.
In the plant manufacturing cork wood, the waste or scrap parts are received in bale form, sorted and then sent by suction through metal pipes into high speed grinding machines or revolving knives from which it is drawn by suction throughout by metal blower pipes to duct separators on roof. The dust from the process is collected and bagged and then removed from the premises and sold to manufacturers of linoleum. The cleaned, ground cork passes from the dust separators to steam mixers where high melting point binder is added. After the cork is properly mixed it is placed in steam-heated coolers, then the material is brought to iron, air cooled pressure moulds, after which the edges are trimmed.
Bottle corks are produced by pressing the sheets of cork which may vary from one to three inches in thickness, against cylindrical shape die cutters. These cutters make the cylindrical corks which are afterwards trimmed and shaped in machines fitted with circular knives. The machines consist largely of numerous high speed and revolving knife cutters.
Grinding is Dangerous Process
Cork grinding is, without question, the most dangerous operation around the cork plant because of the tremendous quantities of highly explosive dust created. Furthermore the possibility of grit, sand, gravel or other materials, which might strike fire when struck by the rapidily traveling cutter, getting into the machines may result in the necessary spark of ignition needed to explode the mixture of dust and air in the machinery, or in the atmosphere around it. It is this dust which must be given consideration by fire departments in operating at cork plant fires.
Cork dust is of highly dangerous character owing to its extreme fineness and capacity for remaining suspended in the air for a long time. It requires but a very small source of ignition to fire a mixture of cork dust in air and as a result it falls in Class 1 of inflammable dusts.
Before discussing the handling of cork fires, the following comments on cork dust explosions, as reported in “Dust Explosions,” by Price and Brown, may prove of interest.
“Philadelphia, Pa.—An accumulation of cork dust on some pipes in a dryer caused a flame which ignited the dust and resulted in an explosion in a plant in Philadelphia on Aug. 13th, 1913. The plant was partially destroyed. A second explosion occurred in the same mill on March 27th. 1914, caused by the ignition of the dust by sparks from foreign materials passing through the grinding rolls. This was not as extensive an explosion as the former one, and resulted in only a small loss.
“Baltimore, Md.-—An explosion occurred in a corkworks in Baltimore, Md., on June 27th, 1917. Overheated cork from an attrition mill was carried through the conveyor into a min where it ignited the dust, causing the explosion.
“Nicetown. Pa.—Seven workmen were seriously iniured and a large oilcloth and linoleum plant in Nicetown, Philadelphia, Pa., was nearly destroyed on Feb. 27th. 1918, as the result of a fire and dust explosion. The fire, of unknown origin, was carried through stock to bolting reels on the fourth floor and then through other spouts to screw conveyors where it was discovered. It spread rapidly but was under control when water was turned on a pile of powdered cork in one portion of the plant. As soon as the water struck the cork dust, a cloud was thrown into suspension and a serious explosion resulted.
“Philadelphia, Pa.—A small fire and explosion occurred in a cork factory in Philadelphia. Pa., Feb, 1st. 1919. Friction from a broken belt as it wound around the shaft caused the fire which exploded the dust. The force of the explosion raised the roof.”
The above emphasize three points:
First, the facility with which the explosions take place. second, the danger of fire passing through ducts in a cork plant: third, the danger of using fire streams carelessly, in that they may displace dust which, upon mixing with air and igniting, explodes.
Operating on the Fire
Where a fire occurs in a cork factory, particularly one manufacturing floor covering or similar material, certain conditions may be expeted. In the first place, there is apt to be great quantities of finished material on hand which throws off very dense smoke. Quantities of linseed oil are apt to be encountered. The dust explosion hazard is always present. Fire may extend throughout the entire plant by way of ducts, and the dust collecting system may even expedite the spread of fire by carrying burning particles through the dust collecting system.
As usual, ventilation is very necessary at cork plant fires. It is accomplished in the same manner as done in other types of establishments.
Force entrance into building and get lines in operation so as to check the spread of the fire, taking care to direct the lines so that no large amount of dust which may have lodged on rafters, or other points of repose, may be displaced. Delegate an officer, or man. to open electric service switch which will shut down the floor equipment (in the event that the plant is in operation and foremen or other plant officials cannot be located to do this).
If the quantities of exposed cork dust are on hand, sprays rather than solid streams must be employed to prevent unnecessarily disturbing the dust. Sprays will also tend to clear the atmosphere and thus check the possibility of explosion. Furthermore the presence of the water in the atmosphere will retard explosion should such occur.
If cork dust bins are uncovered, and can readily be closed, see that this is done at once. Do not unnecessarily wet down stock of material either raw or finished, unless it is necessary to do so in order to extinguish, or to hold the fire from spreading.
In the event that floors show signs of weakening, and collapse of floor is possible, withdraw men from building so that in the event that floors give way men will not be injured by such collapse nor by clust explosions which might result from dust being thrown into the air.
Work of Forest Service Successful
During the past summer the Forest Service of the Department of Agriculture has had considerable success in extinguishing forest fires before they spread over a wide area.
Modern fire-fighting equipment, improved roads and organization are responsible, according to the bureau. Lightning fires put many units to severe tests for several weeks. A total of 1,060 such fires were reported since the first of the year in the northwestern national forests alone.
Greater success in “getting fires young” has characterized this year’s operations, preliminary reports show. Comparatively few have burned over large areas and the total acreage swept by fire has been cut down materially.
Protection costs have been about up to the annual average. Expenses from emergency appropriations mounted sharply the last 10 days of August in Montana, Idaho, Washington, and Oregon, averaging close to $7,000 a day in each of the two northwest regions and about half that amount in California.
The cost of the fire suppression increased considerably in the eastern national forests, total control expenses amounting to $13,943 for the 10-day period. Fires in the lake states region increased the control expenses there to about $1,500 a day. In this region approximately 12,800 acres of national forest have been burned over since January 1. it is reported.
Algoma, Wis., Limits Apparatus Runs.—The city council of Algoma, Wis., voted to limit the fire apparatus runs up to the city limits.
Shamokin, Pa., Threatens Strike.—The five fire companies of Shamokin, Pa., threatened to “walk out” unless the Board of Commissioners at once pays each company $600 due for maintenance. For years $3,000 was split up annually among the companies for the general maintenance of their buildings. This year it was stated that the treasury is low and that the city needs the money for other purposes. Firemen purchased their own buildings and apparatus.