GB885306A - Improvements in or relating to moisture meters - Google Patents

Abstract

885,306. Determining moisture content. MARCONI INSTRUMENTS Ltd. Sept. 23, 1960 [Feb. 2, 1960], No. 3660/60. Class 37. An electrical conductance moisture meter comprises a grinder adapted and arranged to grind material placed in the apparatus, a handle adapted to actuate the grinder, a cell containing electrodes and positioned to receive ground material as it passes out of the grinder, and means, operable by the handle when it has been moved to a predetermined position, for compressing the ground material in the cell to a desired predetermined extent. The apparatus comprises a body or barrel 1, into which are fitted a conductance measuring cell 2, female grinder 3 and housing 4; the latter, which is secured to the barrel 1, being internally screwthreaded and carrying a hollow-threaded screw 17 provided with a counter bore 18 at its lower end and two keyways 19 over the remainder of its length. In operation the top cap 5 is removed and barrel 1 is loaded to a predetermined height with the material, e.g. grain, whose moisture content is to be measured and the cap 5 replaced so that L-shaped locating pins 24 which engage the flattened sides of a spindle 21 carrying a male grinder 22 pass through and beyond the keyways 19 into the counterbore 18, in which position two spring- loaded balls 26 engage the upper groove 25 in the cap 5. When the top cap 5 is now rotated the screw 17 remains stationary due to pressure exerted thereon by spring-loaded ball 27 whilst the spindle 21 and male grinder 22 rotate; the ground material falling into the measuring cell 2. On completion of grinding the top cap is rotated with an upward pressure until the lower ends of the locating pins 24 engage in keyways 19 and the balls 26 engage the lower groove 25 in the top cap. The top cap 5 is again rotated with sufficient force to overcome the resistance of the ball unit 27 and, due to the engagement of the locating pins with the keyways 19, screw 17 also turns causing it to be driven down and causing pressure pad 23 to compress the ground material in the measuring cell and force contact pins 12, 13 of electrodes 10, 11 out from the bottom of the apparatus to permit a measurement to be made between them; this motion being limited by abutment members 15, 16. The two contact pins may be replaced by a single central pin connected to electrode 10; electrode 11 being earthed to the metal body of the grinder unit via housing 7.