DF-7 dilatometer

         Swelling rate (increase in volume when heated) is an important indicator of the quality of coal for coking. It is determined by a standard dilatometric test.
     The DF-7 Dilatometer can perform tests according to ISO 349, ISO 8264, ASTM 5515, and DIN 739 Standards. Specific test programs are defined for each Standard. The dilatometer performs automated dilatometric tests in accordance with the chosen standard. The entire process is controlled by an industrial computer.
     The entire test process, including insertion and removal of testing tubes from the furnace, is automated. The task of the operator is only to prepare the test sample, place it in the test tube, and place the test tube holder in the dilatometer hinge. After the system has been started, the furnace is preheated to the specified initial temperature, the tubes are pushed in with the coal samples, the furnace temperature is increased by the prescribed gradient, and then the actual dilatation test itself follows.
     The temperature, dilatation and contraction data are displayed during the test. Detailed documentation is worked out in the course of the test. The data is archived on the hard disk and backed up. At the end of the test, testing tubes are automatically pulled out of the furnace.
     The course and results of the dilatometric test are stored in files from which they can be generated and displayed on the dilatometer display, printed on a connected printer, and are also available for transmission over a computer network when the device is connected to it.
   From the expansion curves the following numerical parameters of the tested coal samples can be deduced:
         Softening temperature
         Temperature of maximum contraction
         Temperature of maximum dilatation
         Value of maximum contraction
         Value of maximum dilatation.