The quality of wood pellets is regulated by the ISO 17225-2 standard and certified with the ENplus-A1 mark.
According to ENplus A1, only the following properties are permitted:
Water content ≤ 10 m-%
Ash content ≤ 0.7 m-%
Mechanical strength ≥ 98.0 m-%
Calorific value Hu ≥ 4.6 kWh/kg