Design parameters of pipelines for capsule flow (i.e., power of pumps, number of pumps, diameters of capsules, diameter of pipe, etc.) can be calculated if pressure drops of such pipelines are estimated. All major and minor losses that incur at various levels depending on the diameter and type of pipeline selected for hydraulic transportation of capsule trains must be compensated for by the pump. For this purpose, the effect of the different diameter ratios (0.8 and 0.72) on the loss coefficient of elbows (at angles of 90 degrees) in the flow of low-density spherical capsule train was studied experimentally. Relative density of the capsules was 0.87 and their pressure drops were measured at a range of 1.2x104Re1.5x105 and for transportation concentrations from 5 to 15%. Results of this experiment indicate that the higher the concentration, the higher the loss coefficient of the elbow. The increment of the elbow loss coefficient is nearly negligible with increasing the bulk velocity for capsule concentrations up to 10%, but is significantly influenced by the capsule concentration. The effect of the different diameter ratios on the loss coefficient of the elbow is negligible for low capsule concentration.