1975 Volume 37 Issue 2 Pages 193-202
(1) We examined how the static electricity was generated in the boom duster, depending upon the kinds of powders and relative air humidity
(2) We examined the effects of the chemicals to prevent the electrification painted on the inner pipe wall on the kinds of powderes.
(3) Two kinds of powders; Kaolinite and Bentnite showed a similar state of electrification; that is, positive near to the blower in the 10-m pipe, negative in the middle and positive or zero at the end of it. The value of the former was lower. Contrary to these two, the state of electrification of Talc was as follows; negative near the blower in the 10-m pipe, zero in the middle and positive at the end of it, and the absolute quantity of static electricity of Talc was lower than that of the outer two.
(4) It became clear that the effects of the chemicals to prevent the electrification were not so remarkable, but had some influence.
(5) The electrostatic charge was very low at humidity above 70% and it showed a violent variation between positive and negative at humidity 40-50%.
(6) We made calculations to determine the inner pressure of the pipe.
(7) Before the experiment descrived above, we examined the approximations of measured values and calculated values. As for the static pressures, the approximations at the end of the pipe were rather low and, as for the dinamic pressure, so were those near the blower, but the approximations as a whole were close in each case.
(8) Assuming all the orifices of the pipe spout an equal amount of air, we made calculations as to the distributions of the static pressure and orifices, depending upon the diameter of the pipe, the distance between each orifice and the orifice diameters at the pipe end.
