This article was originally published in Electrochemical and Metallurgical Industry Publication of August 1907. Information within this article is therefore correct as of 1907. The publication of this material aims to provide historical insight on the subject and its place in industry.
The use of exhaust fans-for removing acid gases and for conveying gases in chemical works and metallurgical plants are numerous.
Where gases are encountered which would corrode iron and steel it has been customary to line the body of the fan with an enamel or glass, but still more often to use a stoneware fan.
The Schutte & Koerting Co. of Philadelphia, are now constructing fans built entirely of hard lead with the exception of the shaft, which is lead covered.
This material is very strong and exhaust fans constructed of it can be run at high speed.
These hard-lead exhaust fans are finding use in sulphuric acid plants, and may be placed between the glover tower and the first chamber, or between two Gay-Lussac towers where these are used, or at the end of the system, as circumstances may demand.
The fan insures continuous draught under all conditions, resulting in economy of operation, the increased production often being 15 to 20 per cent without enlarging the burners.
The exhaust fan may be set to discharge vertically either top or bottom, or horizontally in either direction. When intended to run at low speeds the bearings are massive and strong, being provided with self-oiling devices. The standard type is arranged for belt drive but electric drive may be substituted if desirable.
Some idea of the work these exhaust fans will accomplish can be gathered from the fact that the largest size has a capacity of 6,800 cubic feet. This exhaust fan is operated at 450 r. p. m. the diameter of the inlet is 28 inches, and it is driven by a pulley 16 inches in diameter by 8 inches wide.
Sand-Lime Brick – The manufacture of sand-lime brick is rapidly becoming an important industry in the United States and is likely to be as profitable here as it has been in Germany for the last ten years. A sand-lime brick is essentially a mass of sand cemented by hydrous lime silicates. The Bricks can easily be made with a crushing strength of over 4,000 pounds per square inch and a tensile strength of over 200 pounds per square inch. A brick plant for making sand-lime bricks, near Sayreton, Alaska, is briefly described in a paper by Charles Butts in the annual economic bulletin (No. 315) of the United States Geological Survey for the year 1906.
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