Ash content of coal is basically defined as the percentage residue of coal after being burnt at a certain temperature. The Ash Content can also be considered as an indirect measurement of the Calorific Value of Coal and is an important technical indicator and one of the main basis for evaluation of coal quality and sales price. Thus monitoring and controlling the Ash Content in Coal is an important factor in determination of Coal Quality. Ash Content is of great significance for social and economic benefits of enterprises. The Online Ash Analyzer uses a dual Gamma - ray penetration method to eliminate the influence of coal porosity, particle size and other factors and to rapidly measure the coal ash and calorific value. This method is the most commonly used technique for fast online Coal Quality Analyzer. This analysis method uses a radioisotope that has a low energy level, and can be used for a long time without requiring replacement, has low radiation and is safe and reliable. This analyser finds extensive use in Coal Mining, Coal Washeries, Coal Blending Plants, Thermal Power Plants, Coking Plants, etc.