20-L-Apparatus (Siwek - Sphere)

1978 - 2016 manufactured by Adolf Kuhner AG, Birsfelden, Switzerland

Determination of explosion indices of dust, gas and hybrid mixtures

Explosion indices

For the efficient prevention of dust explosions by preventive explosion protection (e.g. explosion venting, explosion suppression) it is necessary to know the optimum explosion indices:

  • the dust explosibility
  • the lower explosibility limit (LEL)
  • the maximum explosion pressure (Pmax)
  • the dust-specific characteristic (Kmax)
  • the limiting oxygen concentration (LOC)

These characteristics, especially those that describe the explosion behavior of combustible dusts, can be determined according to a standard procedure in the 20-l laboratory apparatus:

  • ASTM E1226: Standard Test Method for Explosibility of Dust Clouds
  • ASTM E1515: Standard Test Method for MEC - minimum explosible concentration of combustible dusts
  • EN 14034-1: Determination of the maximum explosion pressure Pmax of dust clouds
  • EN 14034-2: Determination of the maximum rate of explosion pressure rise (dp/dt)max of dust clouds
  • EN 14034-3: Determination of the lower explosion limit LEL of dust clouds
  • EN 14034-4: Determination of the limiting oxygen concentration LOC of dust clouds
  • EN ISO/IEC 80079-20-2: Explosive atmopheres. Material characteristics. Combustible dust methods


The test chamber of the laboratory apparatus is a hollow sphere made of stainless steel. A water jacket serves to dissipate the heat of the explosions and to maintain a thermostatically controlled test temperature.

KSEP-Software 7.1

  • Support of larger equipments e.g. 1m3-vessel
  • Automatic check of the explosion indices Pmax and Kmax
  • Usermanagement and access-rights
  • Audit-trail
  • Export of data and curves



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