The severity of an explosion caused by the ignition of a flammable atmosphere in a confined space is defined by the (maximum) rate of pressure rise resulting from the expanding fire ball and the maximum explosion pressure developed.

Dust samples of varying quantities are dispersed within a spherical enclosure with a volume of 20 liters and are ignited by chemical igniters with a total energy of 10,000 Joules (10KJ). The rate of pressure rise as well as the maximum pressure of the resulting deflagration is measured. Data obtained is used to calculate the explosion severity index (Kst) value of the powder/dust material. Kst can be used for the purposes of designing explosion protection measures in a plant.

The Explosion Severity Test is performed in accordance with the requirements of the current edition of the American Society for Testing and Materials (ASTM) E1226.

• Maximum Explosion Pressure (Pmax)
• Maximum Rate of Pressure Rise (dP/dt) max
• Explosion Index (Kst)