GB396098A - Apparatus for determining the moisture content of flour, corn, beet pulp, tobacco and other moisture containing substances - Google Patents

Abstract

396,098. Capacitance measurements. LONG, C. H. W., 81, Eastgate Street, Bury St. Edmunds, Suffolk. Jan. 29, 1932, No. 2777. [Class 37.] To determine the moisture content of flour, corn, beet pulp, tobacco or other substance, a measured quantity of the substance is arranged in an electric circuit (a selected electrical, characteristic of which is predetermined) in such a manner as to produce a variation in the said characteristic which may be ascertained from indicating means operatively connected in the circuit and which is substantially proportional to the moisture content of the substance. The apparatus described comprises an oscillator circuit A and a detector circuit B, the detector circuit having a thermionic valve V<2> arranged for anode bend rectification and coupled to the oscillator circuit by an inductance L<2> that is shunted by a condenser C<3>. The condenser C<3> is constructed in the form of a cell and is mounted upon the top of the casing by a plug and socket connection. The condenser is formed by a pair of aluminium plates spaced apart by distance-pieces of insulating material at the sides and at the bottom, and covered on their inner faces with sheets of insulating material such as " Paxolin." The circuit A is caused to oscillate at a desired frequency and by adjustment of the condenser C<4> a maximum reading is obtained from the microammeter M A in the detector circuit. A predetermined weight of the substance to be tested is placed in the cell condenser C<3> and the condenser C<4> again adjusted until a maximum reading is obtained in the microammeter. The difference between the two readings of the condenser C<4> is read off on a graph or chart forming a standard of reference for the particular substance. In a modification the cell condenser may be arranged in the oscillator circuit. The dial of the condenser C<4> may be provided with a frictionally held pointer which is set at zero when the detector circuit is tuned to give a maximum reading in the microammeter with the condenser C<3> empty ; direct readings of the moisture content may thus be obtained when the condenser C<3> is filled. Reference has been directed by the Comptroller to Specification 275,741, [Class 37, Electricity, Measuring &c.].