of the magnified sample these manual and optical techniques give equivalent results fig1 4 show data taken on an image processing microscope at 100x magnification of the nominal 650 u00b0 f flash liquid product from a two stage ebullated bed process pilot unit circled points indicate that downstream control valve plugging was observed these data were taken from two studies conducted at different space velocity and recycle rate and with different feedstocks described in tables i and ii as shown in fig1 and 2 control valve plugging due to agglomeration occurred at a particle coverage of the field greater than about 37 area percent which corresponds to a maximum agglomerate size greater than about 800 microns fig1 and an average diameter greater than about 29 microns fig2 fig3 shows the comparison between sediment content by ip 375 86 and the field coverage by insolubles for the same set of data shown in fig1 and 2 control valve plugging occurred at an insoluble agglomerate coverage greater than 37 area percent 100 of the time one control valve plugging data point occurred at insoluble agglomerates coverage of less than 37 area percent in contrast control valve plugging occurred 44 of the time when the ip sediment was greater than 0 7 wt for the set of.