In order to transport soil through pipes economically, it is important to grasp a correct verocity of soilwater mixtures. Lately an electromagnetic flow meter is bing used for this purpose, which has been widery employed in measuring flow rates of the water or homogeneous mixtures, and a lot of studies on it are reported but few dealing with its characteristics or applicable limit at time of transporting soil.
　This report presents the result of the test done to investigate the applicable limit of an electromagnetic flow meter and its accuracy under transportation of soil. By using the electromagnetic flow meter of 100mm ID, the behaviour of particles in a pipe was observed to obtain the relationship between the conditions of flow of mixtures and the values indicated by it. The testing installation has a 100-mm line, about 70-m long altogether, inserting the measuring pipe on the way, of both 3-m steel and acrylic jointless tubes, and the behaviour of particles could be observed through transparent tubes, included one in the measuring pipe itself, of 7.8m in length. Materials used here are two kinds of sand with mean grain sizes of 0.25mm and 1.28mm, and a gravel of 7mm. Measuring instruments consist of electromagnetic flow meter, measuring tank to measure the flow rate and the soil content at the outlet, mud meter for consistency in a pipe, pressure gauges, etc..
　Wihtin our test, the error of values indicated was 2 or 3 per cent at maximum, in case of transporting soil generally and even installing its detector horizontally.