Particle size: 6mm to 8mm for domestic and small scale systems, 10-12 mm for larger systems Moisture content: less than 10% Calorific value: less than 4.7kWh/kg Ash content: less than 1% (low), less than 3% (standard) or less than 6% (high); to be clearly labelled Bulk density: less than 600 kg/m Sulfur content: less than 300 ppm Chlorine: less than: 800ppm Only additives: lignin and trace amounts of vegetable oil as a die lubricantMechanical durability of pellets is specified in EN 335, with determination by technical standard CEN/TS 15210-1:2005.The CEN/TC 355 standards include detailed specifications for sampling and testing biomass fuel.