It is recognized that powder feeders are important in particulate systems as the control means. Very little is known, however, of the characteristics of the -eeders. In the present paper static and dynamic characteristics of a belt feeder, screw feeder, vibra-screw feeder, and Flo-tron are experimentally studied. On the basis of this study, futher discussion into their characteristics is made, and it reveals that the insta ntaneous feed rate of the screw feeder oscillates with afirly large amplitude. For the vibra-screw feeder, however, the amplitude becomes smaller as the velocity of revolution increases. Especially for the belt feeder, the step responses are theoretically analyzed to find that the weighing method has a time delay in the response. This fact must be taken into consideration in the automatic control of the particulate system.

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The authors make an experiment of the pulsating flow of Cu-powder through an orifice.
In this experiment, we adopt the method of letting Cu-powder fall on the stick tape that run under the orifice at a high speed and obtain the following three results.
(1) The phenomenon of binetic bridging appear on the stick tape by the frequency of 1/500-1/600per second.
(2) The quantity of discharged Cu-powder decreases only in the case of using the orifices with thickness of 15mm and 20mm.
(3) The period in which each bridging is sustained is apt to become short with the increase of the orifice diameter.

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The fluctuation of the flowing-out quantity of granules from the flat-bottomed hopper was investigated. Results are as follows;
(i) The model hopper are made to continuing its vibration by the momentum change caused by the flowout of granules, because the hopper used is supported by two canti-levers (whose other ends are fixed) at its side walls.
(ii) For the measured signals (that seems to be a kind of random waves), mainly, statistical analysis was performed for the discrete time series which are sliced from the alove random waves, and was drawn out the so-called ‘hidden-periodicity’ through the calculation of ‘autocorrelation coefficient’, ‘power-spectral density’ and ‘energy spectrum distribution’.
(iii) The dominant periodical components or frequencies, thus obtained, vary with the width of the outlet at the underside of our model hopper. (First, the main frequency component increases slowly, then rapidly increasing as the width of the slit becomes larger.)
(iv) These results (tendencies) are thought to correspond to the tendency exsisting between the slit width and the frequency of the arching action of granules occuring at the vicinity of the outlet of the hopper.

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In preceding papers, we reported some measurements of lateral pressures acting on the inside wall ot full-sized grain bins. We showed in these works that the pressures which occured during discharge are much greater than those of initial static conditions.
The present report mentioned about both the lateral pressure measurements on a full-sized deep bin and the flow patterns of granular materials during discharge from model silo.
According to these tests, the principal results are obtained as follows.
(1) The fundamental flow patterns which occure during discharge from silo are one of the very important causes for the dynamic over-pressures.
(2) There are three different characteristics of this dynamic pressure of materials and these phenomena relate to the fundamental flow patterns.
(3) Basing on these flow patterns, we present an approximate theoretical solution of these dynamic overpressures acting on the walls of deep bin.

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Caking mechanism of common salt was studied from a behavior of a small amount of liquid on the surface of the salt crystals and following results were obtained.
1. The caking is an attachment of salt crystals either by pressure or by recrystallization. The caking of the salt in a warehouse is attributed to the atter.
2. Contact loci of the caked salt were observed usually to be edges and faces, not points, with a microscope.
3. Cubes of rock salt splited, deformed and crushed at pressures 50, 500 and 1, 000kg/cm². respectively.
4. Effect of the liquid on the caking is attributed to the deposited crystals from the liquid by either cooling or drying calculated by applying an oceanic quinary system to the liquid.

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