Effects of dietary n-3 polyunsaturated fatty acids and ... - FINS

1 st WorkshopXIII International Feed Technology Symposiumcomponents as well as semi-finished and finished products is a necessarysupplementation of the available data records (e.g. BIA-GESTIS-DUST-EX database)METHODS FOR CHARACTERISING THE DUSTINGBEHAVIOURThe requirements for characterising the dusting behaviour of bulk materials (in thelaboratory scale) result from operational processes during which dust is raised anddispersed. For the grain processing, those are mainly impact and shear stresses due toconveying and transport processes.For characterising the dust generation by impact stresses, a single-drop process (designPalas DustView) was used in the frame of the research project. The sample (sample size30 g normally) drops through a downpipe (length 500 mm) into a dust chamber. Lasersand detectors measure the reduction of the initial intensity of the laser (opacity). Themeasured result is given as dimensionless index from the values 0.5 s and 30 s [Palas].The rotation-drum method according to Heubach (Heubach Dustmeter) is used fordetermining the dust generation from powder by rotating under mechanical stress. Hereshear stresses are mostly efficient. The construction of the used rotation drum isillustrated in Figure 1 as standard process.dusting unit (drum)V = 2.5 lmeasuring and control unitwith drive and vacuum pumpair intakebaffle platesseparator (coarse particles)V = 1 lvacuum pumpsamplerapperair filtration unitFigure 1. Rotation-Drum-Method, design Heubach Dustmeter (standard)The material sample (sample size 100 g normally) is added into the rotation drum(volume 2.5 l). The drum rotates for 5 min at a speed of 30 min -1 . An air throughput of20 l/min is necessary. Dispersible dust contents are released by the rotation movement.They are captured by the air flow and deposited on a filter with defined porosity. Theamount of the deposited dust is determined gravimetrically. The declaration of the16