The low rank coal, especially brown coal, has large contents of moisture and volatile matter, so, if the volatile matter of such a coal is analyzed by JIS method, its analytical value has a tendency to give a too high value because of flashing and partial combustion of sample.
This study has been carried out to establish the analytical method of volatile matter of brown coal and lignite which is based on the loss in mass, less that due to moisture, when the sample is heated out of contact with air under standardized conditions.
Experimental results show that it is essential for avoiding the sparking effect and the partial burning of sample to take 0.5g of the sample and to heat the sample by two stage system and to pass inert gas into the muffle furnace in the overall duration of the measurement.
Improved method provides reliable analitical values. The repeatability is good and the coefficient of variation is 0.5%.