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INDUSTRIAL AND ENGINEERING CHEMISTRY
Throughout the work described in this paper all the coal samples used were “fresh,” in that only an unavoidable minimum time of exposure to air was permitted between sampling and testing. It is, however, entirely possible that some of the coking power of the coals was destroyed during the briquetting process, and that some of the coking constituents may have been lost by distillation into the stream of nitrogen d u r k g the deformation measurements. The authors wish to express their appreciation of helpful suggestions and criticism given b y A. C. Fieldner and J. D. D&s, both of the U. S. Bureau of Mines.
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Literature Cited (1) Brewer, R. E., and Atkinaon, R. G., IND. EXQ.CHEM., Anal. Ed., 8,443 (1936). (2) Seyler, C. A,, Collierg Guardian, 142, 401-4, 488-90, 577-9 (1931). 8. Wales Inst. BWrs., 47,9-14 (1931). (3) SeYler, c. A.3
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RECEIVED February 18, 1937. Presented before the Division of Gas and Fuel Chemistry at the 93rd Meeting of the American Chemical Society, Chapel Hill, N. C.,April 12 to 16, 1937. Published by permission of the Director, 0.S.Bureau of Mines. (Not subject to copyright.)
An Improved Machine for Testing Ductility of Bituminous Substances ROBERT R. THURSTON AND C. E. CUMMINGS The Texas Company, Beacon, N. Y.
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HE ductility of a bituminous material is measured by the distance to which it will elongate before breaking, when two ends of a briquet of the material are pulled apart a t a specified speed and temperature. The accepted procedure for conducting this test is outlined in Method D-113-35 of the American Society for Testing Materials, and specifies that a brass mold of definite dimensions shall be used for holding the specimen to be tested so that a cross section of material 1 cm. square can be elongated. The usual rate of elongation is 5 em. per minute, and the customary temperature of the water bath in which the test is carried out is 25’ C. (77” F.), although other speeds and temperatures are frequently used.
FIGURE 1. IMPROVED DUCTILITY MACHINE The machine by which this test is accomplished is not, described or specified by the A. 8. T. ?VI.,but the usualmachines available on the market are constructed of stone and permit a total elongation of the specimen of from 100 to 200 em. The driving mechanism is ordinarily a screw which is submerged in the liquid and consequently disturbs the placidity of the bath during testing. This construction not only interferes with complete visibility of the specimens under test, but also fails to provide for constant temperature control. An improved ductility machine has been developed at The Texas Company’s Research Laboratories.
The bath itself is a Monel metal tank, placed inside a sheetsteel tank,, provided with circulating liquid between the tanks. The liquid is preferably water, which is maintained automatically at a constant temperature by means of a cold-water coil and an electric heating element actuated by the mercury temperature control shown at the far corner of the bath. The motor shown on top of the machine at the near corner of the bath drives a paddle by means of a vertical shaft which keeps the water in the jacket circulating from end to end around a long vertical baffle between the inner and outer tanks. By setting the thermoregulator for the desired temperature, the water in the jacket is maintained constantly at this temperature and the bath inside the inner tank is thereby also held a t this temperature without agitation. The test is conducted in the inner bath; a white porcelain late in the bottom makes readily visible the fine black threads of gituminous material, which are formed during the test. The carriage, shown midway between the ends of the bath, is made of Monel metal and rides on rails by means of grooved wheels mounted on ball bearings. It ismoved at the required speed by means of a 0.3cm. (0.125-inch) flexible stainless-steel continuous cable which is wound on a grooved drum and draws the carriage the entire length of the bath at the required speed. Lugs attached to this carriage support the moving end of the molds containing the specimens under test which are beneath the surface of the water. This eliminates all agitation of the bath in which the test is being made and provides for maximum visibility of the s ecimens during testing The stationary end of trie molds, which are pulled apart by means of the carriage, can be placed at either end of the bath underneath the water level. The supports for two molds can be seen at the far end of the bath. Similar supports are attached to the carriage. The machine can be made in different widths to accommodate one, three, or five specimens. The photograph shows a machine built for testing five samples a t once. The driving mechanism shown in the foreground provides for four speeds, any one of which is occasionally required by pur chasing specifications for amhalt: 0.25. 1. 5. and 10 om. per minute. The usual centimeter scale is provided for reading t h e distance to which the specimens are pulled out before breaking. The entire machine is mounted on a pipe frame and is so installed that it is accessible from all sides. The electrical control panel for the motors and automatic controls for the bath are shown in the photograph; they are mounted underneath the driving mechanism attached to the frame in the foreground. When the molds are in place, the test can be started by a clutch which engages the driving mechanism. An automatic electric stop switch stops the driving mechanism when the carriage reaches the end of the bath and the clutch is released to enable the carriage to be moved back to the starting position by hand. R E C E I T ~April D 8, 1937.
