Determination of volumetric concentration of solids in vertical pipeline hydrotransport Marcin Zych, Robert Hanus, Leszek Petryka, Anna Strzępowicz and Piotr Zych EPJ Web of Conferences, 114 (2016) 02146 Published online: 28 March 2016 DOI: 10.1051/epjconf/201611402146