Assessing dust explosion hazard (screening) with the Hartmann tube
The dust explosion hazard posed by a product can be tested in a Hartmann tube. This test is carried out as stipulated in DIN EN ISO 80079-20-2 or VDI 2263-1.
The test substance is fed into the Hartmann tube at various concentrations and whirled up by means of compressed air. The test examines whether the whirled-up test substance can be ignited by an ignition spark with an ignition energy of > 1 J or by a filament ignition with an ignition energy of > 10 J. If the flame detaches from the ignition source it is assessed as ignition. The concentration of the dust-air mixture in the Hartmann tube can be varied incrementally between 100 g/m³ and 4000 g/m³. The test results are evaluated visually.
Assessment of the dust explosion hazard in the Hartmann tube is a screening procedure. A dust can be classified as a dust explosion hazard by this screening if ignition occurs with one of the two ignition types (spark ignition or filament ignition). A complete exclusion of the dust explosion hazard is not possible when screening in the Hartmann tube. If the result of the spark ignition and the filament ignition is negative, the dust explosion hazard must be examined in the 20 L apparatus in order to make a reliable statement on the dust explosion hazard as stipulated in the standard DIN EN ISO 80079-20-2.